Merge branch 'develop' of https://git.hdfgroup.org/scm/hdffv/hdf5 into develop

71 files changed, 976 insertions, 701 deletions

diff --git a/config/commence.am b/config/commence.am
index 830c494..a16eee5 100644
--- a/config/commence.am
+++ b/config/commence.am
@@ -70,7 +70,7 @@ H5CPP=${DESTDIR}$(bindir)/h5c++
 # instead of CFLAGS, as CFLAGS is reserved solely for the user to define.
 # This applies to FCFLAGS, CXXFLAGS, CPPFLAGS, and LDFLAGS as well.
 
-AM_CFLAGS=@AM_CFLAGS@ @H5_CFLAGS@ @H5_ECFLAGS@
+AM_CFLAGS=@AM_CFLAGS@ @H5_CFLAGS@
 AM_FCFLAGS=@AM_FCFLAGS@ @H5_FCFLAGS@
 AM_CXXFLAGS=@AM_CXXFLAGS@ @H5_CXXFLAGS@
 AM_CPPFLAGS=@AM_CPPFLAGS@ @H5_CPPFLAGS@
diff --git a/config/gnu-flags b/config/gnu-flags
index bc120a8..6355ccf 100644
--- a/config/gnu-flags
+++ b/config/gnu-flags
@@ -168,44 +168,12 @@ if test "X-gcc" = "X-$cc_vendor"; then
     # NOTE: Disable the -Wformat-nonliteral from -Wformat=2 here and re-add
     # it to the developer flags.
     #
-    H5_CFLAGS="$H5_CFLAGS -pedantic -Wall -Wextra"
-    H5_ECFLAGS="$H5_ECFLAGS -Werror=bad-function-cast"
-    H5_ECFLAGS="$H5_ECFLAGS -Werror=cast-align"
-    H5_CFLAGS="$H5_CFLAGS -Wcast-qual -Wconversion"
-    H5_ECFLAGS="$H5_ECFLAGS -Werror=declaration-after-statement"
-    DEVELOPER_WARNING_CFLAGS="$DEVELOPER_WARNING_CFLAGS -Wdisabled-optimization"
-    H5_CFLAGS="$H5_CFLAGS -Wfloat-equal"
-    H5_CFLAGS="$H5_CFLAGS -Wformat=2 -Wno-format-nonliteral -Winit-self -Winvalid-pch"
-    H5_ECFLAGS="$H5_ECFLAGS -Werror=missing-declarations"
-    H5_CFLAGS="$H5_CFLAGS -Wmissing-include-dirs"
-    H5_ECFLAGS="$H5_ECFLAGS -Werror=missing-prototypes"
-    H5_ECFLAGS="$H5_ECFLAGS -Werror=nested-externs"
-    H5_ECFLAGS="$H5_ECFLAGS -Werror=old-style-definition"
-    H5_ECFLAGS="$H5_ECFLAGS -Werror=packed"
-    H5_ECFLAGS="$H5_ECFLAGS -Werror=redundant-decls"
-    H5_ECFLAGS="$H5_ECFLAGS -Werror=shadow"
-    H5_ECFLAGS="$H5_ECFLAGS -Werror=strict-prototypes"
-    DEVELOPER_WARNING_CFLAGS="$DEVELOPER_WARNING_CFLAGS -Wswitch-default"
-    DEVELOPER_WARNING_CFLAGS="$DEVELOPER_WARNING_CFLAGS -Wswitch-enum"
-    H5_CFLAGS="$H5_CFLAGS -Wundef"
-    DEVELOPER_WARNING_CFLAGS="$DEVELOPER_WARNING_CFLAGS -Wunused-macros"
-    DEVELOPER_WARNING_CFLAGS="$DEVELOPER_WARNING_CFLAGS -Wunsafe-loop-optimizations"
-    H5_CFLAGS="$H5_CFLAGS -Wwrite-strings"
-
-    #
-    # HDF5 code should not trigger the following warnings under any
-    # circumstances, so ask the compiler to treat them as errors:
-    #
-#   H5_ECFLAGS="$H5_ECFLAGS -Werror=discarded-qualifiers"
-    H5_ECFLAGS="$H5_ECFLAGS -Werror=implicit-function-declaration"
-    H5_CFLAGS="$H5_CFLAGS -Wmaybe-uninitialized"
-    H5_ECFLAGS="$H5_ECFLAGS -Werror=pointer-sign"
-    H5_ECFLAGS="$H5_ECFLAGS -Werror=pointer-to-int-cast"
-    H5_ECFLAGS="$H5_ECFLAGS -Werror=switch"
-    H5_ECFLAGS="$H5_ECFLAGS -Werror=unused-but-set-variable"
-    H5_ECFLAGS="$H5_ECFLAGS -Werror=unused-function"
-    H5_ECFLAGS="$H5_ECFLAGS -Werror=unused-parameter"
-    H5_ECFLAGS="$H5_ECFLAGS -Werror=unused-variable"
+    H5_CFLAGS="$H5_CFLAGS -pedantic -Wall -Wextra -Wbad-function-cast -Wc++-compat -Wcast-align"
+    H5_CFLAGS="$H5_CFLAGS -Wcast-qual -Wconversion -Wdeclaration-after-statement -Wdisabled-optimization -Wfloat-equal"
+    H5_CFLAGS="$H5_CFLAGS -Wformat=2 -Wno-format-nonliteral -Winit-self -Winvalid-pch -Wmissing-declarations -Wmissing-include-dirs"
+    H5_CFLAGS="$H5_CFLAGS -Wmissing-prototypes -Wnested-externs -Wold-style-definition -Wpacked"
+    H5_CFLAGS="$H5_CFLAGS -Wredundant-decls -Wshadow -Wstrict-prototypes -Wswitch-enum -Wswitch-default"
+    H5_CFLAGS="$H5_CFLAGS -Wundef -Wunused-macros -Wunsafe-loop-optimizations -Wwrite-strings"
 
     ######################
     # Developer warnings #
@@ -254,34 +222,17 @@ if test "X-gcc" = "X-$cc_vendor"; then
 
     # gcc 4.3                                                                    
     if test $cc_vers_major -ge 5 -o $cc_vers_major -eq 4 -a $cc_vers_minor -ge 3; then
-        H5_CFLAGS="$H5_CFLAGS -Wlogical-op"
-        #
-        # Lots of noise, questionable benefit:
-        #
-        DEVELOPER_WARNING_CFLAGS="$DEVELOPER_WARNING_CFLAGS -Wlarger-than=2560"
-        #
+        H5_CFLAGS="$H5_CFLAGS -Wlogical-op -Wlarger-than=2560"                   
     fi 
 
     # gcc 4.4
     if test $cc_vers_major -ge 5 -o $cc_vers_major -eq 4 -a $cc_vers_minor -ge 4; then
-        H5_CFLAGS="$H5_CFLAGS -Wsync-nand -Wpacked-bitfield-compat"
-        #
-        # Lots of noise, questionable benefit:
-        #
-        DEVELOPER_WARNING_CFLAGS="$DEVELOPER_WARNING_CFLAGS -Wframe-larger-than=16384"
-        #
+        H5_CFLAGS="$H5_CFLAGS -Wsync-nand -Wframe-larger-than=16384 -Wpacked-bitfield-compat"
     fi
 
     # gcc 4.5
     if test $cc_vers_major -ge 5 -o $cc_vers_major -eq 4 -a $cc_vers_minor -ge 5; then
-        H5_CFLAGS="$H5_CFLAGS -Wstrict-overflow=5 -Wunsuffixed-float-constants"
-        #
-        # -Wjump-misses-init makes lots of noise for a questionable benefit.
-        # Can jumping over an initialization in C cause any harm, if
-        # the variable is never *used* before it has been initialized?
-        #
-        DEVELOPER_WARNING_CFLAGS="$DEVELOPER_WARNING_CFLAGS -Wjump-misses-init"
-        #
+        H5_CFLAGS="$H5_CFLAGS -Wstrict-overflow=5 -Wjump-misses-init -Wunsuffixed-float-constants"
     fi
 
     # gcc 4.6
@@ -293,17 +244,7 @@ if test "X-gcc" = "X-$cc_vendor"; then
 
     # gcc 4.7
     if test $cc_vers_major -ge 5 -o $cc_vers_major -eq 4 -a $cc_vers_minor -ge 7; then
-        #
-        # It's not clear that -Wvector-operation-performance warnings are
-        # actionable.
-        #
-        # -Wstack-usage=8192 warnings need better justification;
-        # if justifiable, should be enabled on a branch and swept up there
-        # before burdening the whole development team.
-        #
-        DEVELOPER_WARNING_CFLAGS="$DEVELOPER_WARNING_CFLAGS -Wstack-usage=8192"
-        DEVELOPER_WARNING_CFLAGS="$DEVELOPER_WARNING_CFLAGS -Wvector-operation-performance"
-
+        H5_CFLAGS="$H5_CFLAGS -Wstack-usage=8192 -Wvector-operation-performance"
         DEVELOPER_WARNING_CFLAGS="$DEVELOPER_WARNING_CFLAGS -Wsuggest-attribute=pure -Wsuggest-attribute=noreturn"
         NO_DEVELOPER_WARNING_CFLAGS="$NO_DEVELOPER_WARNING_CFLAGS -Wno-suggest-attribute=pure -Wno-suggest-attribute=noreturn"
     fi
@@ -322,21 +263,11 @@ if test "X-gcc" = "X-$cc_vendor"; then
     # gcc 5
     if test $cc_vers_major -ge 5; then
         H5_CFLAGS="$H5_CFLAGS -Warray-bounds=2 -Wc99-c11-compat"
-        H5_ECFLAGS="$H5_ECFLAGS -Werror=incompatible-pointer-types"
     fi
 
     # gcc 6
     if test $cc_vers_major -ge 6; then
-        H5_CFLAGS="$H5_CFLAGS -Wunused-const-variable -Whsa -Wnormalized"
-        #
-        # Unacceptably noisy on HDF5 right now.
-        #
-        DEVELOPER_WARNING_CFLAGS="$DEVELOPER_WARNING_CFLAGS -Wnull-dereference"
-        #
-        # Careful!  -Wduplicated-cond, combined with HDF5's heavy use of
-        # macros, can make a lot of noise.
-        #
-        DEVELOPER_WARNING_CFLAGS="$DEVELOPER_WARNING_CFLAGS -Wduplicated-cond"
+        H5_CFLAGS="$H5_CFLAGS -Wnull-dereference -Wunused-const-variable -Wduplicated-cond -Whsa -Wnormalized"
     fi
 
     # gcc 7
@@ -347,13 +278,6 @@ if test "X-gcc" = "X-$cc_vendor"; then
 
     # gcc 8
     if test $cc_vers_major -ge 8; then
-        # For GCC 8, promote maybe-initialized warnings to an error.  GCC 8
-        # reports 0 maybe-uninitialized warnings where earlier versions
-        # make many false reports.  GCC 8 seems to analyze calls to static
-        # in order to detect initializations that occur there.  It's possible
-        # that GCC 8 only performs that analysis at -O3, though.
-        H5_ECFLAGS="$H5_ECFLAGS -Werror=maybe-uninitialized"
-        H5_ECFLAGS="$H5_ECFLAGS -Werror=cast-function-type"
         DEVELOPER_WARNING_CFLAGS="$DEVELOPER_WARNING_CFLAGS -Wstringop-overflow=4 -Wsuggest-attribute=cold -Wsuggest-attribute=malloc"
         NO_DEVELOPER_WARNING_CFLAGS="$NO_DEVELOPER_WARNING_CFLAGS -Wno-suggest-attribute=cold -Wno-suggest-attribute=malloc"
         H5_CFLAGS="$H5_CFLAGS -Wattribute-alias -Wcast-align=strict -Wshift-overflow=2"
diff --git a/configure.ac b/configure.ac
index 5851b32..0eada60 100644
--- a/configure.ac
+++ b/configure.ac
@@ -103,11 +103,7 @@ AC_SUBST([AR_FLAGS])
 
 ## H5_CFLAGS (and company) are for CFLAGS that should be used on HDF5, but
 ## not exported to h5cc (or h5fc, etc.)
-##
-## H5_ECFLAGS is for warnings that should be treated as errors.
-##
 AC_SUBST([H5_CFLAGS])
-AC_SUBST([H5_ECFLAGS])
 AC_SUBST([H5_CPPFLAGS])
 AC_SUBST([H5_FCFLAGS])
 AC_SUBST([H5_CXXFLAGS])
diff --git a/hl/src/H5DS.c b/hl/src/H5DS.c
index ce61028..b24f887 100644
--- a/hl/src/H5DS.c
+++ b/hl/src/H5DS.c
@@ -1434,10 +1434,6 @@ herr_t H5DSset_label(hid_t did, unsigned int idx, const char *label)
       char  ** buf;            /* discarding the 'const' qualifier in the free */
       char const ** const_buf; /* buf calls */
     } u;
-
-    u.buf = NULL;
-    u.const_buf = NULL;
-
     /*-------------------------------------------------------------------------
     * parameter checking
     *-------------------------------------------------------------------------
diff --git a/hl/test/H5srcdir_str.h.in b/hl/test/H5srcdir_str.h.in
index ba30a88..bab1df3 100644
--- a/hl/test/H5srcdir_str.h.in
+++ b/hl/test/H5srcdir_str.h.in
@@ -16,5 +16,5 @@
  */
 
 /* Set the 'srcdir' path from configure time */
-#define config_srcdir "@srcdir@"
+static const char *config_srcdir = "@srcdir@";
 
diff --git a/src/H5Cdbg.c b/src/H5Cdbg.c
index cb1d0e2..1f55e86 100644
--- a/src/H5Cdbg.c
+++ b/src/H5Cdbg.c
@@ -319,8 +319,9 @@ H5C_dump_cache_skip_list(H5C_t * cache_ptr, char * calling_fcn)
                (int)(entry_ptr->is_dirty),
                entry_ptr->type->name);
 
-            HDfprintf(stdout, "		node_ptr = %p, item = %p\n",
-                      node_ptr, H5SL_item(node_ptr));
+            HDfprintf(stdout, "		node_ptr = 0x%llx, item = %p\n",
+                      (unsigned long long)node_ptr,
+                      H5SL_item(node_ptr));
 
             /* increment node_ptr before we delete its target */
             node_ptr = H5SL_next(node_ptr);
diff --git a/src/H5Cpkg.h b/src/H5Cpkg.h
index b8648f0..9156c0d 100644
--- a/src/H5Cpkg.h
+++ b/src/H5Cpkg.h
@@ -4694,7 +4694,7 @@ struct H5C_t {
     uint32_t                    num_last_entries;
 #if H5C_DO_SANITY_CHECKS
     int32_t			slist_len_increase;
-    int64_t			slist_size_increase;
+    ssize_t			slist_size_increase;
 #endif /* H5C_DO_SANITY_CHECKS */
 
     /* Fields for maintaining list of tagged entries */
diff --git a/src/H5Dchunk.c b/src/H5Dchunk.c
index 4d139c7..381ca4a 100644
--- a/src/H5Dchunk.c
+++ b/src/H5Dchunk.c
@@ -284,8 +284,7 @@ static int H5D__chunk_format_convert_cb(const H5D_chunk_rec_t *chunk_rec, void *
 static herr_t H5D__chunk_set_info_real(H5O_layout_chunk_t *layout, unsigned ndims,
     const hsize_t *curr_dims, const hsize_t *max_dims);
 static void *H5D__chunk_mem_alloc(size_t size, const H5O_pline_t *pline);
-static void *H5D__chunk_mem_xfree(void *chk, void *pline);
-static void H5D__chunk_mem_xfree_wrapper(void *chk, void *pline);
+static void *H5D__chunk_mem_xfree(void *chk, const void *pline);
 static void *H5D__chunk_mem_realloc(void *chk, size_t size,
     const H5O_pline_t *pline);
 static herr_t H5D__chunk_cinfo_cache_reset(H5D_chunk_cached_t *last);
@@ -1101,10 +1100,14 @@ H5D__chunk_io_init(const H5D_io_info_t *io_info, const H5D_type_info_t *type_inf
     H5D_chunk_map_t *fm)
 {
     const H5D_t *dataset = io_info->dset;     /* Local pointer to dataset info */
+    H5S_t *tmp_mspace = NULL;   /* Temporary memory dataspace */
     hssize_t old_offset[H5O_LAYOUT_NDIMS];  /* Old selection offset */
     htri_t file_space_normalized = FALSE;   /* File dataspace was normalized */
+    H5T_t *file_type = NULL;    /* Temporary copy of file datatype for iteration */
+    hbool_t iter_init = FALSE;  /* Selection iteration info has been initialized */
     unsigned f_ndims;           /* The number of dimensions of the file's dataspace */
     int sm_ndims;               /* The number of dimensions of the memory buffer's dataspace (signed) */
+    char bogus;                 /* "bogus" buffer to pass to selection iterator */
     unsigned u;                 /* Local index variable */
     herr_t ret_value = SUCCEED;	/* Return value		*/
 
@@ -1428,7 +1431,7 @@ H5D__chunk_mem_alloc(size_t size, const H5O_pline_t *pline)
  *-------------------------------------------------------------------------
  */
 static void *
-H5D__chunk_mem_xfree(void *chk, void *_pline)
+H5D__chunk_mem_xfree(void *chk, const void *_pline)
 {
     const H5O_pline_t *pline = (const H5O_pline_t *)_pline;
 
@@ -1444,17 +1447,6 @@ H5D__chunk_mem_xfree(void *chk, void *_pline)
     FUNC_LEAVE_NOAPI(NULL)
 } /* H5D__chunk_mem_xfree() */
 
-/* H5D__chunk_mem_xfree_wrapper() safely adapts the type of
- * H5D__chunk_mem_xfree() to an H5MM_free_t callback, without making
- * compilers warn.  It is used with H5D__chunk_mem_xfree_wrapper(), for
- * example.
- */
-static void
-H5D__chunk_mem_xfree_wrapper(void *chk, void *_pline)
-{
-    (void)H5D__chunk_mem_xfree(chk, _pline);
-}
-
 
 /*-------------------------------------------------------------------------
  * Function:    H5D__chunk_mem_realloc
@@ -2147,6 +2139,12 @@ H5D__create_chunk_mem_map_1d(const H5D_chunk_map_t *fm)
 {
     H5D_chunk_info_t *chunk_info;           /* Pointer to chunk information */
     H5SL_node_t *curr_node;                 /* Current node in skip list */
+    hsize_t     file_sel_start[H5S_MAX_RANK];    /* Offset of low bound of file selection */
+    hsize_t     file_sel_end[H5S_MAX_RANK]; /* Offset of high bound of file selection */
+    hsize_t     mem_sel_start[H5S_MAX_RANK]; /* Offset of low bound of file selection */
+    hsize_t     mem_sel_end[H5S_MAX_RANK];  /* Offset of high bound of file selection */
+    hssize_t    adjust[H5S_MAX_RANK];       /* Adjustment to make to all file chunks */
+    unsigned    u;                          /* Local index variable */
     herr_t	ret_value = SUCCEED;        /* Return value */
 
     FUNC_ENTER_STATIC
@@ -2171,18 +2169,17 @@ H5D__create_chunk_mem_map_1d(const H5D_chunk_map_t *fm)
         chunk_info->mspace_shared = TRUE;
     } /* end if */
     else {
+        HDassert(fm->m_ndims == 1);
         hsize_t     mem_sel_start[H5S_MAX_RANK]; /* Offset of low bound of file selection */
         hsize_t     mem_sel_end[H5S_MAX_RANK];  /* Offset of high bound of file selection */
 
-        HDassert(fm->m_ndims == 1);
-
         if(H5S_SELECT_BOUNDS(fm->mem_space, mem_sel_start, mem_sel_end) < 0)
             HGOTO_ERROR(H5E_DATASPACE, H5E_CANTGET, FAIL, "can't get file selection bound info")
 
         /* Iterate over each chunk in the chunk list */
         curr_node = H5SL_first(fm->sel_chunks);
         while(curr_node) {
-            hsize_t    schunk_points;          /* Number of elements in chunk selection */
+            hssize_t    schunk_points;          /* Number of elements in chunk selection */
             hsize_t     tmp_count = 1;
 
             /* Get pointer to chunk's information */
@@ -4453,7 +4450,7 @@ H5D__chunk_allocate(const H5D_io_info_t *io_info, hbool_t full_overwrite, hsize_
         /* (delay allocating fill buffer for VL datatypes until refilling) */
         /* (casting away const OK - QAK) */
         if(H5D__fill_init(&fb_info, NULL, (H5MM_allocate_t)H5D__chunk_mem_alloc,
-                (void *)pline, H5D__chunk_mem_xfree_wrapper, (void *)pline,
+                (void *)pline, (H5MM_free_t)H5D__chunk_mem_xfree, (void *)pline,
                 &dset->shared->dcpl_cache.fill, dset->shared->type,
                 dset->shared->type_id, (size_t)0, orig_chunk_size) < 0)
             HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "can't initialize fill buffer info")
@@ -7155,6 +7152,7 @@ H5D__get_num_chunks(const H5D_t *dset, const H5S_t H5_ATTR_UNUSED *space, hsize_
     hsize_t            num_chunks = 0;          /* Number of written chunks */
     H5D_rdcc_ent_t     *ent;                    /* Cache entry  */
     const H5D_rdcc_t   *rdcc = NULL;            /* Raw data chunk cache */
+    const H5O_layout_t *layout;                 /* Dataset layout */
     herr_t             ret_value = SUCCEED;     /* Return value */
 
     FUNC_ENTER_PACKAGE_TAG(dset->oloc.addr)
@@ -7164,6 +7162,7 @@ H5D__get_num_chunks(const H5D_t *dset, const H5S_t H5_ATTR_UNUSED *space, hsize_
     HDassert(space);
     HDassert(nchunks);
 
+    layout = &(dset->shared->layout);    /* Dataset layout */
     rdcc = &(dset->shared->cache.chunk); /* raw data chunk cache */
     HDassert(rdcc);
 
diff --git a/src/H5FDhdfs.c b/src/H5FDhdfs.c
index 0b954cf..819d200 100644
--- a/src/H5FDhdfs.c
+++ b/src/H5FDhdfs.c
@@ -581,6 +581,7 @@ hid_t
 H5FD_hdfs_init(void)
 {
     hid_t ret_value = H5I_INVALID_HID; /* Return value */
+    unsigned int bin_i;
 
     FUNC_ENTER_NOAPI(FAIL)
 
diff --git a/src/H5FDlog.c b/src/H5FDlog.c
index 1c7d549..ac5667f 100644
--- a/src/H5FDlog.c
+++ b/src/H5FDlog.c
@@ -489,8 +489,8 @@ H5FD_log_open(const char *name, unsigned flags, hid_t fapl_id, haddr_t maxaddr)
 #endif
 #ifdef H5_HAVE_GETTIMEOFDAY
     struct timeval timeval_start;
-    struct timeval open_timeval_diff = {0, 0};
-    struct timeval stat_timeval_diff = {0, 0};
+    struct timeval open_timeval_diff;
+    struct timeval stat_timeval_diff;
 #endif /* H5_HAVE_GETTIMEOFDAY */
     h5_stat_t       sb;
     H5FD_t          *ret_value = NULL;  /* Return value */
diff --git a/src/H5FSsection.c b/src/H5FSsection.c
index cf4a587..df67bd9 100644
--- a/src/H5FSsection.c
+++ b/src/H5FSsection.c
@@ -371,10 +371,10 @@ HDfprintf(stderr, "%s: fspace->alloc_sect_size = %Hu, fspace->sect_size = %Hu\n"
     /* Check if section info lock count dropped to zero */
     if(fspace->sinfo_lock_count == 0) {
         hbool_t release_sinfo_space = FALSE;    /* Flag to indicate section info space in file should be released */
-        hbool_t closing_or_flushing = f->shared->closing;      /* Is closing or flushing in progress */
+        hbool_t flush_in_progress = FALSE;      /* Is flushing in progress */
 
-        /* Check whether cache-flush is in progress if closing is not. */
-        if(!closing_or_flushing && H5AC_get_cache_flush_in_progress(f->shared->cache, &closing_or_flushing) < 0)
+        /* Check whether cache is flush_in_progress */
+        if(H5AC_get_cache_flush_in_progress(f->shared->cache, &flush_in_progress) < 0)
             HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, "Can't get flush_in_progress")
 
         /* Check if we actually protected the section info */
@@ -390,7 +390,7 @@ HDfprintf(stderr, "%s: fspace->alloc_sect_size = %Hu, fspace->sect_size = %Hu\n"
                 cache_flags |= H5AC__DIRTIED_FLAG;
 
                 /* On file close or flushing, does not allow section info to shrink in size */
-                if(closing_or_flushing) {
+                if(f->shared->closing || flush_in_progress) {
                     if(fspace->sect_size > fspace->alloc_sect_size)
                         cache_flags |= H5AC__DELETED_FLAG | H5AC__TAKE_OWNERSHIP_FLAG;
                     else
@@ -441,7 +441,7 @@ HDfprintf(stderr, "%s: Relinquishing section info ownership\n", FUNC);
                     /* Set flag to release section info space in file */
                     /* On file close or flushing, only need to release section info with size 
                        bigger than previous section */
-                    if(closing_or_flushing) {
+                    if(f->shared->closing || flush_in_progress) {
                         if(fspace->sect_size > fspace->alloc_sect_size)
                             release_sinfo_space = TRUE;
                         else
diff --git a/src/H5Fint.c b/src/H5Fint.c
index 435c1be..153ec2f 100644
--- a/src/H5Fint.c
+++ b/src/H5Fint.c
@@ -3654,9 +3654,9 @@ done:
 
 
 /*-------------------------------------------------------------------------
- * Function:    H5F__get_file_id
+ * Function:    H5F_get_file_id
  *
- * Purpose:     The package version of H5Iget_file_id(), obtains the file
+ * Purpose:     The private version of H5Iget_file_id(), obtains the file
  *              ID given an object ID.
  *
  * Return:      Success:    The file ID associated with the object
@@ -3665,22 +3665,31 @@ done:
  *-------------------------------------------------------------------------
  */
 hid_t
-H5F__get_file_id(H5F_t *file, hbool_t app_ref)
+H5F_get_file_id(H5VL_object_t *vol_obj, H5I_type_t obj_type, hbool_t app_ref)
 {
-    hid_t file_id = H5I_INVALID_HID;    /* File ID */
-    hid_t ret_value = H5I_INVALID_HID;  /* Return value */
+    void *vol_obj_file = NULL;                  /* File object pointer */
+    H5VL_loc_params_t loc_params;               /* Location parameters */
+    hid_t           file_id = H5I_INVALID_HID;  /* File ID for object */
+    hid_t           ret_value = H5I_INVALID_HID; /* Return value */
 
-    FUNC_ENTER_PACKAGE
+    FUNC_ENTER_NOAPI(H5I_INVALID_HID)
+
+    /* Set location parameters */
+    loc_params.type = H5VL_OBJECT_BY_SELF;
+    loc_params.obj_type = obj_type;
+
+    /* Retrieve VOL file from object */
+    if(H5VL_object_get(vol_obj, &loc_params, H5VL_OBJECT_GET_FILE, H5P_DATASET_XFER_DEFAULT, H5_REQUEST_NULL, &vol_obj_file) < 0)
+        HGOTO_ERROR(H5E_ATOM, H5E_CANTGET, H5I_INVALID_HID, "can't retrieve file from object")
 
     /* Check if the file's ID already exists */
-    if(H5I_find_id(file, H5I_FILE, &file_id) < 0)
+    if(H5I_find_id(vol_obj_file, H5I_FILE, &file_id) < 0)
         HGOTO_ERROR(H5E_FILE, H5E_CANTGET, H5I_INVALID_HID, "getting file ID failed")
 
     /* If the ID does not exist, register it with the VOL connector */
     if(H5I_INVALID_HID == file_id) {
-        if((file_id = H5VL_wrap_register(H5I_FILE, file, app_ref)) < 0)
+        if((file_id = H5VL_register(H5I_FILE, vol_obj_file, vol_obj->connector, app_ref)) < 0)
             HGOTO_ERROR(H5E_FILE, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to atomize file handle")
-        file->id_exists = TRUE;
     } /* end if */
     else {
         /* Increment ref count on existing ID */
@@ -3693,44 +3702,6 @@ H5F__get_file_id(H5F_t *file, hbool_t app_ref)
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5F__get_file_id() */
-
-
-/*-------------------------------------------------------------------------
- * Function:    H5F_get_file_id
- *
- * Purpose:     The private version of H5Iget_file_id(), obtains the file
- *              ID given an object ID.
- *
- * Return:      Success:    The file ID associated with the object
- *              Failure:    H5I_INVALID_HID
- *
- *-------------------------------------------------------------------------
- */
-hid_t
-H5F_get_file_id(hid_t obj_id, H5I_type_t type, hbool_t app_ref)
-{
-    H5VL_object_t  *vol_obj;                    /* File info */
-    hid_t           file_id = H5I_INVALID_HID;  /* File ID for object */
-    hid_t           ret_value = H5I_INVALID_HID; /* Return value */
-
-    FUNC_ENTER_NOAPI(H5I_INVALID_HID)
-
-    /* Get the object pointer */
-    if(NULL == (vol_obj = H5VL_vol_object(obj_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "invalid identifier")
-
-    /* Get the file through the VOL */
-    if(H5VL_file_optional(vol_obj, H5P_DATASET_XFER_DEFAULT, H5_REQUEST_NULL, H5VL_NATIVE_FILE_GET_FILE_ID, (int)type, (int)app_ref, &file_id) < 0)
-        HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, H5I_INVALID_HID, "unable to get file ID")
-    if(H5I_INVALID_HID == file_id)
-        HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, H5I_INVALID_HID, "unable to get the file ID through the VOL")
-
-    /* Set return value */
-    ret_value = file_id;
-
-done:
-    FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5F_get_file_id() */
 
 
diff --git a/src/H5Fpkg.h b/src/H5Fpkg.h
index 7d9a090..6e2c994 100644
--- a/src/H5Fpkg.h
+++ b/src/H5Fpkg.h
@@ -412,7 +412,6 @@ H5_DLL herr_t H5F__start_swmr_write(H5F_t *f);
 H5_DLL herr_t H5F__close(H5F_t *f);
 H5_DLL herr_t H5F__set_libver_bounds(H5F_t *f, H5F_libver_t low, H5F_libver_t high);
 H5_DLL H5F_t *H5F__get_file(void *obj, H5I_type_t type);
-H5_DLL hid_t H5F__get_file_id(H5F_t *file, hbool_t app_ref);
 H5_DLL herr_t H5F__get_cont_info(const H5F_t *f, H5VL_file_cont_info_t *info);
 
 /* File mount related routines */
diff --git a/src/H5Fprivate.h b/src/H5Fprivate.h
index e1a8a2f..cfb796c 100644
--- a/src/H5Fprivate.h
+++ b/src/H5Fprivate.h
@@ -732,7 +732,7 @@ typedef enum H5F_prefix_open_t {
 /* Private functions */
 H5_DLL H5F_t *H5F_open(const char *name, unsigned flags, hid_t fcpl_id, hid_t fapl_id);
 H5_DLL herr_t H5F_try_close(H5F_t *f, hbool_t *was_closed/*out*/);
-H5_DLL hid_t H5F_get_file_id(hid_t obj_id, H5I_type_t id_type, hbool_t app_ref);
+H5_DLL hid_t H5F_get_file_id(H5VL_object_t *vol_obj, H5I_type_t obj_type, hbool_t app_ref);
 
 /* Functions that retrieve values from the file struct */
 H5_DLL H5F_libver_t H5F_get_low_bound(const H5F_t *f);
diff --git a/src/H5Fsuper_cache.c b/src/H5Fsuper_cache.c
index ce216a2..125d6cf 100644
--- a/src/H5Fsuper_cache.c
+++ b/src/H5Fsuper_cache.c
@@ -347,9 +347,9 @@ static herr_t
 H5F__cache_superblock_get_final_load_size(const void *_image, size_t image_len,
     void *_udata, size_t *actual_len)
 {
-    const uint8_t *image = _image; /* Pointer into raw data buffer */
+    const uint8_t *image = (const uint8_t *)_image;   			    /* Pointer into raw data buffer */
     H5F_superblock_cache_ud_t *udata = (H5F_superblock_cache_ud_t *)_udata; /* User data */
-    H5F_super_t sblock; /* Temporary file superblock */
+    H5F_super_t sblock;                 /* Temporary file superblock */
     htri_t ret_value = SUCCEED;         /* Return value */
 
     FUNC_ENTER_STATIC
@@ -361,15 +361,6 @@ H5F__cache_superblock_get_final_load_size(const void *_image, size_t image_len,
     HDassert(*actual_len == image_len);
     HDassert(image_len >= H5F_SUPERBLOCK_FIXED_SIZE + 6);
 
-    /* Initialize because GCC 5.5 does not realize that
-     * H5F__superblock_prefix_decode() initializes it.
-     *
-     * TBD condition on compiler version.
-     */
-    sblock.super_vers = 0;
-    sblock.sizeof_addr = 0;
-    sblock.sizeof_size = 0;
-
     /* Deserialize the file superblock's prefix */
     if(H5F__superblock_prefix_decode(&sblock, &image, udata, TRUE) < 0)
         HGOTO_ERROR(H5E_FILE, H5E_CANTDECODE, FAIL, "can't decode file superblock prefix")
@@ -402,7 +393,7 @@ done:
 static htri_t
 H5F__cache_superblock_verify_chksum(const void *_image, size_t len, void *_udata)
 {
-    const uint8_t *image = _image;    	/* Pointer into raw data buffer */
+    const uint8_t *image = (const uint8_t *)_image;    	/* Pointer into raw data buffer */
     H5F_superblock_cache_ud_t *udata = (H5F_superblock_cache_ud_t *)_udata; /* User data */
     uint32_t stored_chksum;     /* Stored metadata checksum value */
     uint32_t computed_chksum;   /* Computed metadata checksum value */
@@ -448,7 +439,7 @@ H5F__cache_superblock_deserialize(const void *_image, size_t len, void *_udata,
 {
     H5F_super_t         *sblock = NULL; /* File's superblock */
     H5F_superblock_cache_ud_t *udata = (H5F_superblock_cache_ud_t *)_udata; /* User data */
-    const uint8_t	*image = _image; /* Pointer into raw data buffer */
+    const uint8_t	*image = (const uint8_t *)_image;       /* Pointer into raw data buffer */
     H5F_super_t         *ret_value = NULL;      /* Return value */
 
     FUNC_ENTER_STATIC
@@ -673,7 +664,7 @@ H5F__cache_superblock_serialize(const H5F_t *f, void *_image, size_t H5_ATTR_UNU
     void *_thing)
 {
     H5F_super_t *sblock = (H5F_super_t *)_thing;      /* Pointer to the object */
-    uint8_t *image = _image;         /* Pointer into raw data buffer */
+    uint8_t *image = (uint8_t *)_image;         /* Pointer into raw data buffer */
     haddr_t rel_eof;            /* Relative EOF for file */
     herr_t ret_value = SUCCEED; /* Return value */
 
@@ -879,7 +870,7 @@ static herr_t
 H5F__cache_drvrinfo_get_final_load_size(const void *_image, size_t image_len,
     void *_udata, size_t *actual_len)
 {
-    const uint8_t *image = _image; /* Pointer into raw data buffer */
+    const uint8_t *image = (const uint8_t *)_image;   			/* Pointer into raw data buffer */
     H5F_drvrinfo_cache_ud_t *udata = (H5F_drvrinfo_cache_ud_t *)_udata;	/* User data */
     H5O_drvinfo_t drvrinfo;     /* Driver info */
     herr_t ret_value = SUCCEED; /* Return value */
@@ -893,7 +884,6 @@ H5F__cache_drvrinfo_get_final_load_size(const void *_image, size_t image_len,
     HDassert(*actual_len == image_len);
     HDassert(image_len == H5F_DRVINFOBLOCK_HDR_SIZE);
 
-    drvrinfo.len = 0;
     /* Deserialize the file driver info's prefix */
     if(H5F__drvrinfo_prefix_decode(&drvrinfo, NULL, &image, udata, TRUE) < 0)
         HGOTO_ERROR(H5E_FILE, H5E_CANTDECODE, FAIL, "can't decode file driver info prefix")
@@ -926,7 +916,7 @@ H5F__cache_drvrinfo_deserialize(const void *_image, size_t len, void *_udata,
 {
     H5O_drvinfo_t       *drvinfo = NULL; /* Driver info */
     H5F_drvrinfo_cache_ud_t *udata = (H5F_drvrinfo_cache_ud_t *)_udata;     /* User data */
-    const uint8_t	*image = _image; /* Pointer into raw data buffer */
+    const uint8_t	*image = (const uint8_t *)_image;       /* Pointer into raw data buffer */
     char                drv_name[9];    /* Name of driver */
     H5O_drvinfo_t       *ret_value = NULL;      /* Return value */
 
@@ -1020,7 +1010,7 @@ H5F__cache_drvrinfo_serialize(const H5F_t *f, void *_image, size_t len,
     void *_thing)
 {
     H5O_drvinfo_t *drvinfo = (H5O_drvinfo_t *)_thing;   /* Pointer to the object */
-    uint8_t *image = _image;         /* Pointer into raw data buffer */
+    uint8_t *image = (uint8_t *)_image;         /* Pointer into raw data buffer */
     uint8_t *dbuf;              /* Pointer to beginning of driver info */
     herr_t ret_value = SUCCEED; /* Return value */
 
diff --git a/src/H5HFcache.c b/src/H5HFcache.c
index ab448ef..2d1c1f2 100644
--- a/src/H5HFcache.c
+++ b/src/H5HFcache.c
@@ -406,7 +406,7 @@ static herr_t
 H5HF__cache_hdr_get_final_load_size(const void *_image, size_t image_len,
     void *_udata, size_t *actual_len)
 {
-    H5HF_hdr_t hdr; /* Temporary fractal heap header */
+    H5HF_hdr_t hdr;             /* Temporary fractal heap header */
     const uint8_t *image = (const uint8_t *)_image;       /* Pointer into into supplied image */
     H5HF_hdr_cache_ud_t *udata = (H5HF_hdr_cache_ud_t *)_udata; /* User data for callback */
     herr_t ret_value = SUCCEED; /* Return value */
@@ -419,12 +419,6 @@ H5HF__cache_hdr_get_final_load_size(const void *_image, size_t image_len,
     HDassert(actual_len);
     HDassert(*actual_len == image_len);
 
-    /* Initialize because GCC 5.5 does not realize that the
-     * H5HF__hdr_prefix_decode() call is sufficient to initialize.
-     * GCC 8 is clever enough to see that the variable is initialized.
-     * TBD condition on compiler version.
-     */
-    hdr.filter_len = 0;
     /* Deserialize the fractal heap header's prefix */
     if(H5HF__hdr_prefix_decode(&hdr, &image) < 0)
         HGOTO_ERROR(H5E_HEAP, H5E_CANTDECODE, FAIL, "can't decode fractal heap header prefix")
diff --git a/src/H5HFtiny.c b/src/H5HFtiny.c
index 79d790b..0c27180 100644
--- a/src/H5HFtiny.c
+++ b/src/H5HFtiny.c
@@ -377,7 +377,7 @@ done:
 herr_t
 H5HF_tiny_remove(H5HF_hdr_t *hdr, const uint8_t *id)
 {
-    size_t enc_obj_size = 0;            /* Encoded object size */
+    size_t enc_obj_size;                /* Encoded object size */
     herr_t ret_value = SUCCEED;         /* Return value */
 
     FUNC_ENTER_NOAPI_NOINIT
diff --git a/src/H5HGcache.c b/src/H5HGcache.c
index 9f6e73f..29e88df 100644
--- a/src/H5HGcache.c
+++ b/src/H5HGcache.c
@@ -205,7 +205,7 @@ static herr_t
 H5HG__cache_heap_get_final_load_size(const void *image, size_t image_len,
     void *udata, size_t *actual_len)
 {
-    H5HG_heap_t heap; /* Global heap */
+    H5HG_heap_t heap;                   /* Global heap */
     herr_t ret_value = SUCCEED;         /* Return value */
 
     FUNC_ENTER_STATIC
@@ -217,12 +217,6 @@ H5HG__cache_heap_get_final_load_size(const void *image, size_t image_len,
     HDassert(*actual_len == image_len);
     HDassert(image_len == H5HG_MINSIZE);
 
-    /* Initialize because GCC 5.5 cannot see that
-     * H5HG__hdr_deserialize() initializes.
-     *
-     * TBD condition on compiler version.
-     */
-    heap.size = 0;
     /* Deserialize the heap's header */
     if(H5HG__hdr_deserialize(&heap, (const uint8_t *)image, (const H5F_t *)udata) < 0)
         HGOTO_ERROR(H5E_HEAP, H5E_CANTDECODE, FAIL, "can't decode global heap prefix")
diff --git a/src/H5I.c b/src/H5I.c
index 76faab1..c3c2d46 100644
--- a/src/H5I.c
+++ b/src/H5I.c
@@ -2270,7 +2270,14 @@ H5Iget_file_id(hid_t obj_id)
 
     /* Call internal function */
     if (H5I_FILE == type || H5I_DATATYPE == type || H5I_GROUP == type || H5I_DATASET == type || H5I_ATTR == type) {
-        if ((ret_value = H5F_get_file_id(obj_id, type, TRUE)) < 0)
+        H5VL_object_t *vol_obj = NULL; /* Object token of obj_id */
+
+        /* Get the VOL object */
+        if(NULL == (vol_obj = H5VL_vol_object(obj_id)))
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "invalid location identifier")
+
+        /* Get the file ID */
+        if ((ret_value = H5F_get_file_id(vol_obj, type, TRUE)) < 0)
             HGOTO_ERROR(H5E_ATOM, H5E_CANTGET, H5I_INVALID_HID, "can't retrieve file ID")
     } /* end if */
     else
diff --git a/src/H5O.c b/src/H5O.c
index b79914c..7e5694a 100644
--- a/src/H5O.c
+++ b/src/H5O.c
@@ -278,7 +278,7 @@ H5Oopen_by_addr(hid_t loc_id, haddr_t addr)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "invalid location identifier")
 
     /* Get the file for the object */
-    if((file_id = H5F_get_file_id(loc_id, vol_obj_type, FALSE)) < 0)
+    if((file_id = H5F_get_file_id(vol_obj, vol_obj_type, FALSE)) < 0)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "not a file or file object")
 
     /* Retrieve VOL object */
diff --git a/src/H5Ocopy_ref.c b/src/H5Ocopy_ref.c
index d8efeb5..20b8454 100644
--- a/src/H5Ocopy_ref.c
+++ b/src/H5Ocopy_ref.c
@@ -24,7 +24,6 @@
 /****************/
 
 #include "H5Omodule.h"          /* This source code file is part of the H5O module */
-#define H5F_FRIEND              /* Suppress error about including H5Fpkg   */
 #define H5R_FRIEND              /* Suppress error about including H5Rpkg   */
 
 
@@ -32,7 +31,7 @@
 /* Headers */
 /***********/
 #include "H5private.h"          /* Generic Functions                        */
-#include "H5Fpkg.h"             /* File                                     */
+#include "H5Fprivate.h"         /* File                                     */
 #include "H5Iprivate.h"         /* IDs                                      */
 #include "H5Lprivate.h"         /* Links                                    */
 #include "H5MMprivate.h"        /* Memory management                        */
@@ -359,7 +358,7 @@ H5O__copy_expand_ref_object2(H5O_loc_t *src_oloc, hid_t tid_src, H5T_t *dt_src,
         HGOTO_ERROR(H5E_OHDR, H5E_CANTCONVERT, FAIL, "datatype conversion failed")
 
     /* Retrieve loc ID */
-    if((dst_loc_id = H5F__get_file_id(dst_oloc->file, FALSE)) < 0)
+    if((dst_loc_id = H5F_get_id(dst_oloc->file)) < 0)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a file or file object")
 
     /* Making equivalent references in the destination file */
diff --git a/src/H5Oint.c b/src/H5Oint.c
index 0029976..b97ff30 100644
--- a/src/H5Oint.c
+++ b/src/H5Oint.c
@@ -31,7 +31,6 @@
 /* Headers */
 /***********/
 #include "H5private.h"          /* Generic Functions                        */
-#include "H5CXprivate.h"        /* API contexts                             */
 #include "H5Eprivate.h"         /* Error handling                           */
 #include "H5Fprivate.h"         /* File access                              */
 #include "H5FLprivate.h"        /* Free lists                               */
diff --git a/src/H5Pmapl.c b/src/H5Pmapl.c
index 59da91a..fe5be0f 100644
--- a/src/H5Pmapl.c
+++ b/src/H5Pmapl.c
@@ -138,7 +138,6 @@ done:
 } /* end H5P__macc_reg_prop() */
 
 
-#ifdef H5_HAVE_MAP_API
 /*-------------------------------------------------------------------------
  * Function:    H5Pset_map_iterate_hints
  *
@@ -215,4 +214,4 @@ H5Pget_map_iterate_hints(hid_t mapl_id, size_t *key_prefetch_size, size_t *key_a
 done:
     FUNC_LEAVE_API(ret_value)
 } /* end H5Pget_map_iterate_hints() */
-#endif /*  H5_HAVE_MAP_API */
+
diff --git a/src/H5R.c b/src/H5R.c
index 11b75ca..31b2bcd 100644
--- a/src/H5R.c
+++ b/src/H5R.c
@@ -103,7 +103,7 @@ H5Rcreate_object(hid_t loc_id, const char *name, H5R_ref_t *ref_ptr)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
 
     /* Get the file for the object */
-    if((file_id = H5F_get_file_id(loc_id, obj_type, FALSE)) < 0)
+    if((file_id = H5F_get_file_id(vol_obj, obj_type, FALSE)) < 0)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a file or file object")
 
     /* Retrieve VOL file object */
@@ -186,7 +186,7 @@ H5Rcreate_region(hid_t loc_id, const char *name, hid_t space_id,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
 
     /* Get the file for the object */
-    if((file_id = H5F_get_file_id(loc_id, obj_type, FALSE)) < 0)
+    if((file_id = H5F_get_file_id(vol_obj, obj_type, FALSE)) < 0)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a file or file object")
 
     /* Retrieve VOL file object */
@@ -265,7 +265,7 @@ H5Rcreate_attr(hid_t loc_id, const char *name, const char *attr_name,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
 
     /* Get the file for the object */
-    if((file_id = H5F_get_file_id(loc_id, obj_type, FALSE)) < 0)
+    if((file_id = H5F_get_file_id(vol_obj, obj_type, FALSE)) < 0)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a file or file object")
 
     /* Retrieve VOL file object */
diff --git a/src/H5Rdeprec.c b/src/H5Rdeprec.c
index b9bdffa..0636da9 100644
--- a/src/H5Rdeprec.c
+++ b/src/H5Rdeprec.c
@@ -123,7 +123,7 @@ H5Rget_obj_type1(hid_t id, H5R_type_t ref_type, const void *ref)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5G_UNKNOWN, "invalid location identifier")
 
     /* Get object token */
-    if(H5R__decode_token_compat(id, vol_obj_type, ref_type, buf, &obj_token) < 0)
+    if(H5R__decode_token_compat(vol_obj, vol_obj_type, ref_type, buf, &obj_token) < 0)
         HGOTO_ERROR(H5E_REFERENCE, H5E_CANTDECODE, H5G_UNKNOWN, "unable to get object token")
 
     /* Set location parameters */
@@ -183,7 +183,7 @@ H5Rdereference1(hid_t obj_id, H5R_type_t ref_type, const void *ref)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "invalid location identifier")
 
     /* Get object token */
-    if(H5R__decode_token_compat(obj_id, vol_obj_type, ref_type, buf, &obj_token) < 0)
+    if(H5R__decode_token_compat(vol_obj, vol_obj_type, ref_type, buf, &obj_token) < 0)
         HGOTO_ERROR(H5E_REFERENCE, H5E_CANTDECODE, H5I_INVALID_HID, "unable to get object token")
 
     /* Set location parameters */
@@ -265,7 +265,7 @@ H5Rcreate(void *ref, hid_t loc_id, const char *name, H5R_type_t ref_type,
         HGOTO_ERROR(H5E_REFERENCE, H5E_CANTGET, FAIL, "unable to retrieve object token")
 
     /* Get the file for the object */
-    if((file_id = H5F_get_file_id(loc_id, vol_obj_type, FALSE)) < 0)
+    if((file_id = H5F_get_file_id(vol_obj, vol_obj_type, FALSE)) < 0)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a file or file object")
 
     /* Retrieve VOL object */
@@ -351,7 +351,7 @@ H5Rget_obj_type2(hid_t id, H5R_type_t ref_type, const void *ref,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
 
     /* Get object token */
-    if(H5R__decode_token_compat(id, vol_obj_type, ref_type, buf, &obj_token) < 0)
+    if(H5R__decode_token_compat(vol_obj, vol_obj_type, ref_type, buf, &obj_token) < 0)
         HGOTO_ERROR(H5E_REFERENCE, H5E_CANTDECODE, FAIL, "unable to get object token")
 
     /* Set location parameters */
@@ -415,7 +415,7 @@ H5Rdereference2(hid_t obj_id, hid_t oapl_id, H5R_type_t ref_type,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "invalid location identifier")
 
     /* Get object token */
-    if(H5R__decode_token_compat(obj_id, vol_obj_type, ref_type, buf, &obj_token) < 0)
+    if(H5R__decode_token_compat(vol_obj, vol_obj_type, ref_type, buf, &obj_token) < 0)
         HGOTO_ERROR(H5E_REFERENCE, H5E_CANTDECODE, H5I_INVALID_HID, "unable to get object token")
 
     /* Set location parameters */
@@ -479,7 +479,7 @@ H5Rget_region(hid_t id, H5R_type_t ref_type, const void *ref)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "invalid location identifier")
 
     /* Get the file for the object */
-    if((file_id = H5F_get_file_id(id, vol_obj_type, FALSE)) < 0)
+    if((file_id = H5F_get_file_id(vol_obj, vol_obj_type, FALSE)) < 0)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "not a file or file object")
 
     /* Retrieve VOL object */
@@ -548,7 +548,7 @@ H5Rget_name(hid_t id, H5R_type_t ref_type, const void *ref, char *name,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, (-1), "invalid location identifier")
 
     /* Get object token */
-    if(H5R__decode_token_compat(id, vol_obj_type, ref_type, buf, &obj_token) < 0)
+    if(H5R__decode_token_compat(vol_obj, vol_obj_type, ref_type, buf, &obj_token) < 0)
         HGOTO_ERROR(H5E_REFERENCE, H5E_CANTDECODE, (-1), "unable to get object token")
 
     /* Set location parameters */
diff --git a/src/H5Rint.c b/src/H5Rint.c
index 9fbc7ef..558c095 100644
--- a/src/H5Rint.c
+++ b/src/H5Rint.c
@@ -413,6 +413,7 @@ H5R__destroy(H5R_ref_priv_t *ref)
             break;
         case H5R_OBJECT1:
         case H5R_DATASET_REGION1:
+            break;
         case H5R_BADTYPE:
         case H5R_MAXTYPE:
             HDassert("invalid reference type" && 0);
@@ -423,7 +424,7 @@ H5R__destroy(H5R_ref_priv_t *ref)
     } /* end switch */
 
     /* Decrement refcount of attached loc_id */
-    if((ref->loc_id != H5I_INVALID_HID) && (H5I_dec_ref(ref->loc_id) < 0))
+    if(ref->type && (ref->loc_id != H5I_INVALID_HID) && (H5I_dec_ref(ref->loc_id) < 0))
         HGOTO_ERROR(H5E_REFERENCE, H5E_CANTDEC, FAIL, "decrementing location ID failed")
 
 done:
@@ -1169,8 +1170,8 @@ H5R__encode_region(H5S_t *space, unsigned char *buf, size_t *nalloc)
 
     /* Don't encode if buffer size isn't big enough or buffer is empty */
     if(buf && *nalloc >= ((size_t)buf_size + 2 * H5_SIZEOF_UINT32_T)) {
-        int rank;
         p = (uint8_t *)buf;
+        int rank;
 
         /* Encode the size for safety check */
         UINT32ENCODE(p, (uint32_t)buf_size);
@@ -1479,18 +1480,18 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5R__decode_token_compat(hid_t id, H5I_type_t type, H5R_type_t ref_type,
+H5R__decode_token_compat(H5VL_object_t *vol_obj, H5I_type_t type, H5R_type_t ref_type,
     const unsigned char *buf, H5VL_token_t *obj_token)
 {
     hid_t file_id = H5I_INVALID_HID;    /* File ID for region reference */
-    void *vol_obj_file = NULL;
+    H5VL_object_t *vol_obj_file = NULL;
     H5VL_file_cont_info_t cont_info = {H5VL_CONTAINER_INFO_VERSION, 0, 0, 0};
     herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_PACKAGE
 
     /* Get the file for the object */
-    if((file_id = H5F_get_file_id(id, type, FALSE)) < 0)
+    if((file_id = H5F_get_file_id(vol_obj, type, FALSE)) < 0)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a file or file object")
 
     /* Retrieve VOL object */
diff --git a/src/H5Rpkg.h b/src/H5Rpkg.h
index 19f3115..7471487 100644
--- a/src/H5Rpkg.h
+++ b/src/H5Rpkg.h
@@ -118,7 +118,7 @@ H5_DLL herr_t   H5R__encode_heap(H5F_t *f, unsigned char *buf, size_t *nalloc, c
 H5_DLL herr_t   H5R__decode_heap(H5F_t *f, const unsigned char *buf, size_t *nbytes, unsigned char **data_ptr, size_t *data_size);
 H5_DLL herr_t   H5R__free_heap(H5F_t *f, const unsigned char *buf, size_t nbytes);
 
-H5_DLL herr_t   H5R__decode_token_compat(hid_t id, H5I_type_t type, H5R_type_t ref_type, const unsigned char *buf, H5VL_token_t *obj_token);
+H5_DLL herr_t   H5R__decode_token_compat(H5VL_object_t *vol_obj, H5I_type_t type, H5R_type_t ref_type, const unsigned char *buf, H5VL_token_t *obj_token);
 
 H5_DLL herr_t   H5R__encode_token_obj_compat(const H5VL_token_t *obj_token, size_t token_size, unsigned char *buf, size_t *nalloc);
 H5_DLL herr_t   H5R__decode_token_obj_compat(const unsigned char *buf, size_t *nbytes, H5VL_token_t *obj_token, size_t token_size);
diff --git a/src/H5Rpublic.h b/src/H5Rpublic.h
index 045e04a..ce54ac4 100644
--- a/src/H5Rpublic.h
+++ b/src/H5Rpublic.h
@@ -70,18 +70,14 @@ typedef haddr_t hobj_ref_t;
  * machine (8 bytes currently) plus an int.
  * Note! This type can only be used with the "native" HDF5 VOL connector.
  */
-typedef struct {
-    unsigned char content[H5R_DSET_REG_REF_BUF_SIZE];
-} hdset_reg_ref_t;
+typedef unsigned char hdset_reg_ref_t[H5R_DSET_REG_REF_BUF_SIZE];
 
 /**
  * Opaque reference type. The same reference type is used for object,
  * dataset region and attribute references. This is the type that
  * should always be used with the current reference API.
  */
-typedef struct {
-    unsigned char content[H5R_REF_BUF_SIZE];
-} H5R_ref_t;
+typedef unsigned char H5R_ref_t[H5R_REF_BUF_SIZE];
 
 /********************/
 /* Public Variables */
diff --git a/src/H5SL.c b/src/H5SL.c
index ec06395..5f00fb8 100644
--- a/src/H5SL.c
+++ b/src/H5SL.c
@@ -1394,7 +1394,7 @@ H5SL_search(H5SL_t *slist, const void *key)
 {
     H5SL_node_t *x;                             /* Current node to examine */
     uint32_t hashval = 0;                       /* Hash value for key */
-    void *ret_value = NULL;                     /* Return value */
+    void *ret_value;                            /* Return value */
 
     FUNC_ENTER_NOAPI_NOINIT_NOERR
 
@@ -1695,7 +1695,7 @@ H5SL_find(H5SL_t *slist, const void *key)
 {
     H5SL_node_t *x;                             /* Current node to examine */
     uint32_t hashval = 0;                       /* Hash value for key */
-    H5SL_node_t *ret_value = NULL;              /* Return value */
+    H5SL_node_t *ret_value;                     /* Return value */
 
     FUNC_ENTER_NOAPI_NOINIT_NOERR
 
diff --git a/src/H5SM.c b/src/H5SM.c
index 91ef98b..290e575 100644
--- a/src/H5SM.c
+++ b/src/H5SM.c
@@ -313,7 +313,7 @@ ssize_t
 H5SM_get_index(const H5SM_master_table_t *table, unsigned type_id)
 {
     size_t x;
-    unsigned type_flag = 0;
+    unsigned type_flag;
     ssize_t ret_value = FAIL;
 
     FUNC_ENTER_NOAPI_NOINIT
@@ -353,7 +353,7 @@ htri_t
 H5SM_type_shared(H5F_t *f, unsigned type_id)
 {
     H5SM_master_table_t *table = NULL;  /* Shared object master table */
-    unsigned type_flag = 0;             /* Flag corresponding to message type */
+    unsigned type_flag;                 /* Flag corresponding to message type */
     size_t u;                           /* Local index variable */
     htri_t ret_value = FALSE;           /* Return value */
 
diff --git a/src/H5Sselect.c b/src/H5Sselect.c
index bf0441f..664f4b5 100644
--- a/src/H5Sselect.c
+++ b/src/H5Sselect.c
@@ -2599,7 +2599,12 @@ H5S_select_project_intersection(const H5S_t *src_space, const H5S_t *dst_space,
     const H5S_t *src_intersect_space, H5S_t **new_space_ptr,
     hbool_t share_selection)
 {
-    H5S_t *new_space = NULL;           /* New dataspace constructed */
+    H5S_t *new_space = NULL;            /* New dataspace constructed */
+    H5S_t *tmp_src_intersect_space = NULL; /* Temporary SIS converted from points->hyperslabs */
+    H5S_sel_iter_t ss_iter;             /* Selection iterator for src_space */
+    hbool_t ss_iter_init = FALSE;       /* Whether ss_iter has been initialized */
+    H5S_sel_iter_t ds_iter;             /* Selection iterator for dst_space */
+    hbool_t ds_iter_init = FALSE;       /* Whether ds_iter has been initialized */
     herr_t ret_value = SUCCEED;         /* Return value */
 
     FUNC_ENTER_NOAPI(FAIL)
@@ -2609,6 +2614,7 @@ H5S_select_project_intersection(const H5S_t *src_space, const H5S_t *dst_space,
     HDassert(dst_space);
     HDassert(src_intersect_space);
     HDassert(new_space_ptr);
+    HDassert(H5S_GET_SELECT_NPOINTS(src_space) == H5S_GET_SELECT_NPOINTS(dst_space));
 
     /* Create new space, using dst extent.  Start with "all" selection. */
     if(NULL == (new_space = H5S_create(H5S_SIMPLE)))
@@ -2618,7 +2624,7 @@ H5S_select_project_intersection(const H5S_t *src_space, const H5S_t *dst_space,
 
     /* If the intersecting space is "all", the intersection must be equal to the
      * source space and the projection must be equal to the destination space */
-    if(src_intersect_space->select.type->type == H5S_SEL_ALL) {
+    if(H5S_GET_SELECT_TYPE(src_intersect_space) == H5S_SEL_ALL) {
         /* Copy the destination selection. */
         if(H5S_select_copy(new_space, dst_space, FALSE) < 0)
             HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCOPY, FAIL, "can't copy destination space selection")
@@ -2632,20 +2638,99 @@ H5S_select_project_intersection(const H5S_t *src_space, const H5S_t *dst_space,
         if(H5S_select_none(new_space) < 0)
             HGOTO_ERROR(H5E_DATASPACE, H5E_CANTDELETE, FAIL, "can't change selection")
     } /* end if */
-    /* If any of the spaces use point selection, fall back to general algorithm */
-    else if((src_intersect_space->select.type->type == H5S_SEL_POINTS)
-            || (src_space->select.type->type == H5S_SEL_POINTS)
-            || (dst_space->select.type->type == H5S_SEL_POINTS))
-        HGOTO_ERROR(H5E_DATASPACE, H5E_UNSUPPORTED, FAIL, "point selections not currently supported")
     else {
-        HDassert(src_intersect_space->select.type->type == H5S_SEL_HYPERSLABS);
-        HDassert(src_space->select.type->type != H5S_SEL_NONE);
-        HDassert(dst_space->select.type->type != H5S_SEL_NONE);
-
-        /* Intersecting space is hyperslab selection.  Call the hyperslab
-         * routine to project to another hyperslab selection. */
-        if(H5S__hyper_project_intersection(src_space, dst_space, src_intersect_space, new_space, share_selection) < 0)
-            HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCLIP, FAIL, "can't project hyperslab onto destination selection")
+        /* If the source intersect space is a point selection, convert it to a
+         * hyperslab (discarding ordering).  We can get away with this because
+         * the order does not matter for the source intersect space */
+        /* Maybe we should just leave it as a point selection for the point by
+         * point algorithm?  The search through the selection in
+         * H5S_SELECT_INTERSECT_BLOCK will likely be O(N) either way.  -NAF */
+        if(H5S_GET_SELECT_TYPE(src_intersect_space) == H5S_SEL_POINTS) {
+            H5S_pnt_node_t *curr_pnt = src_intersect_space->select.sel_info.pnt_lst->head;
+
+            /* Create dataspace and copy extent */
+            if(NULL == (tmp_src_intersect_space = H5S_create(H5S_SIMPLE)))
+                HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCREATE, FAIL, "unable to create temporary source intersect dataspace")
+            if(H5S__extent_copy_real(&tmp_src_intersect_space->extent, &src_intersect_space->extent, FALSE) < 0)
+                HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCOPY, FAIL, "unable to copy source intersect space extent")
+
+            /* Iterate over points */
+            for(curr_pnt = src_intersect_space->select.sel_info.pnt_lst->head; curr_pnt; curr_pnt = curr_pnt->next)
+                /* Add point to hyperslab selection */
+                if(H5S_hyper_add_span_element(tmp_src_intersect_space, src_intersect_space->extent.rank, curr_pnt->pnt) < 0)
+                    HGOTO_ERROR(H5E_DATASPACE, H5E_CANTSELECT, FAIL, "can't add point to temporary dataspace selection")
+
+            /* Redirect local src_intersect_space pointer (will not affect
+             * calling function) */
+            src_intersect_space = tmp_src_intersect_space;
+        } /* end for */
+
+        /* By this point, src_intersect_space must be a hyperslab selection */
+        HDassert(H5S_GET_SELECT_TYPE(src_intersect_space) == H5S_SEL_HYPERSLABS);
+
+        /* If either the source space or the destination space is a point
+         * selection, iterate element by element */
+        if((H5S_GET_SELECT_TYPE(src_space) == H5S_SEL_POINTS)
+                || (H5S_GET_SELECT_TYPE(dst_space) == H5S_SEL_POINTS)) {
+            hsize_t coords[H5S_MAX_RANK];
+            htri_t intersect;
+
+            /* Start with "none" selection */
+            if(H5S_select_none(new_space) < 0)
+                HGOTO_ERROR(H5E_DATASPACE, H5E_CANTDELETE, FAIL, "can't change selection")
+
+            /* Initialize iterators */
+            if(H5S_select_iter_init(&ss_iter, src_space, 1, H5S_SEL_ITER_SHARE_WITH_DATASPACE) < 0)
+                HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINIT, FAIL, "can't initialize source space selection iterator")
+            ss_iter_init = TRUE;
+            if(H5S_select_iter_init(&ds_iter, dst_space, 1, H5S_SEL_ITER_SHARE_WITH_DATASPACE) < 0)
+                HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINIT, FAIL, "can't initialize destination space selection iterator")
+            ds_iter_init = TRUE;
+
+            /* Iterate over points */
+            do {
+                HDassert(ss_iter.elmt_left > 0);
+                HDassert(ss_iter.elmt_left > 0);
+
+                /* Get SS coords */
+                if(H5S_SELECT_ITER_COORDS(&ss_iter, coords) < 0)
+                    HGOTO_ERROR(H5E_DATASPACE, H5E_CANTGET, FAIL, "can't get source selection coordinates")
+
+                /* Check for intersection */
+                if((intersect = H5S_SELECT_INTERSECT_BLOCK(src_intersect_space, coords, coords)) < 0)
+                    HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCOMPARE, FAIL, "can't check for intersection")
+
+                /* Add point if it intersects */
+                if(intersect) {
+                    /* Get DS coords */
+                    if(H5S_SELECT_ITER_COORDS(&ds_iter, coords) < 0)
+                        HGOTO_ERROR(H5E_DATASPACE, H5E_CANTGET, FAIL, "can't get destination selection coordinates")
+
+                    /* Add point to new_space */
+                    if(H5S_select_elements(new_space, H5S_SELECT_APPEND, 1, coords) < 0)
+                        HGOTO_ERROR(H5E_DATASPACE, H5E_CANTSELECT, FAIL, "can't add point to new selection")
+                } /* end if */
+
+                /* Advance iterators */
+                if(H5S_SELECT_ITER_NEXT(&ss_iter, 1) < 0)
+                    HGOTO_ERROR(H5E_DATASPACE, H5E_CANTNEXT, FAIL, "can't advacne source selection iterator")
+                ss_iter.elmt_left--;
+                if(H5S_SELECT_ITER_NEXT(&ds_iter, 1) < 0)
+                    HGOTO_ERROR(H5E_DATASPACE, H5E_CANTNEXT, FAIL, "can't advacne destination selection iterator")
+                ds_iter.elmt_left--;
+            } while(ss_iter.elmt_left > 0);
+            HDassert(H5S_SELECT_ITER_NELMTS(&ds_iter) == 0);
+        } /* end if */
+        else {
+            HDassert(H5S_GET_SELECT_TYPE(src_space) != H5S_SEL_NONE);
+            HDassert(H5S_GET_SELECT_TYPE(dst_space) != H5S_SEL_NONE);
+
+            /* Source and destination selections are all or hyperslab,
+             * intersecting selection is hyperslab.  Call the hyperslab routine
+             * to project to another hyperslab selection. */
+            if(H5S__hyper_project_intersection(src_space, dst_space, src_intersect_space, new_space, share_selection) < 0)
+                HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCLIP, FAIL, "can't project hyperslab onto destination selection")
+        } /* end else */
     } /* end else */
 
     /* load the address of the new space into *new_space_ptr */
@@ -2657,6 +2742,14 @@ done:
         if(new_space && H5S_close(new_space) < 0)
             HDONE_ERROR(H5E_DATASPACE, H5E_CANTRELEASE, FAIL, "unable to release dataspace")
 
+    /* General cleanup */
+    if(tmp_src_intersect_space && H5S_close(tmp_src_intersect_space) < 0)
+        HDONE_ERROR(H5E_DATASPACE, H5E_CANTRELEASE, FAIL, "unable to release temporary dataspace")
+    if(ss_iter_init && H5S_SELECT_ITER_RELEASE(&ss_iter) < 0)
+        HDONE_ERROR(H5E_DATASPACE, H5E_CANTRELEASE, FAIL, "unable to release source selection iterator")
+    if(ds_iter_init && H5S_SELECT_ITER_RELEASE(&ds_iter) < 0)
+        HDONE_ERROR(H5E_DATASPACE, H5E_CANTRELEASE, FAIL, "unable to release destination selection iterator")
+
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5S_select_project_intersection() */
 
@@ -2668,8 +2761,7 @@ done:
  PURPOSE
     Projects the intersection of of the selections of src_space_id and
     src_intersect_space_id within the selection of src_space_id as a
-    selection within the selection of dst_space_id.  Currently does not
-    support point selections.
+    selection within the selection of dst_space_id.
 
  USAGE
     hid_t H5Sselect_project_intersection(src_space_id,dst_space_d,src_intersect_space_id)
@@ -2712,6 +2804,10 @@ H5Sselect_project_intersection(hid_t src_space_id, hid_t dst_space_id,
     if(NULL == (src_intersect_space = (H5S_t *)H5I_object_verify(src_intersect_space_id, H5I_DATASPACE)))
         HGOTO_ERROR(H5E_DATASPACE, H5E_BADTYPE, FAIL, "not a dataspace")
 
+    /* Check numbbers of points selected matches in source and destination */
+    if(H5S_GET_SELECT_NPOINTS(src_space) != H5S_GET_SELECT_NPOINTS(dst_space))
+        HGOTO_ERROR(H5E_DATASPACE, H5E_BADVALUE, FAIL, "number of points selected in source space does not match that in destination space")
+
     /* Perform operation */
     if(H5S_select_project_intersection(src_space, dst_space,
             src_intersect_space, &proj_space, FALSE) < 0)
diff --git a/src/H5T.c b/src/H5T.c
index 3fc59d0..9263158 100644
--- a/src/H5T.c
+++ b/src/H5T.c
@@ -3320,7 +3320,7 @@ done:
  *-------------------------------------------------------------------------
  */
 H5T_t *
-H5T_copy(const H5T_t *old_dt, H5T_copy_t method)
+H5T_copy(H5T_t *old_dt, H5T_copy_t method)
 {
     H5T_t           *new_dt = NULL, *tmp = NULL;
     H5T_shared_t    *reopened_fo = NULL;
diff --git a/src/H5Tconv.c b/src/H5Tconv.c
index 6aea00e..4cc5f3c 100644
--- a/src/H5Tconv.c
+++ b/src/H5Tconv.c
@@ -3609,39 +3609,52 @@ H5T__conv_ref(hid_t src_id, hid_t dst_id, H5T_cdata_t *cdata, size_t nelmts,
                 for(elmtno = 0; elmtno < safe; elmtno++) {
                     size_t buf_size;
                     hbool_t dst_copy = FALSE;
+                    hbool_t is_nil; /* Whether sequence is "nil" */
 
-                    /* Get size of references */
-                    if(0 == (buf_size = src->shared->u.atomic.u.r.cls->getsize(
-                        src->shared->u.atomic.u.r.file, s, src->shared->size,
-                        dst->shared->u.atomic.u.r.file, &dst_copy)))
-                        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "incorrect size")
-
-                    /* Check if conversion buffer is large enough, resize if necessary. */
-                    if(conv_buf_size < buf_size) {
-                        conv_buf_size = buf_size;
-                        if(NULL == (conv_buf = H5FL_BLK_REALLOC(ref_seq, conv_buf, conv_buf_size)))
-                            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for type conversion")
-                        HDmemset(conv_buf, 0, conv_buf_size);
-                    } /* end if */
+                    /* Check for "nil" source sequence */
+                    if((*(src->shared->u.atomic.u.r.cls->isnull))(src->shared->u.atomic.u.r.file, s, &is_nil) < 0)
+                        HGOTO_ERROR(H5E_DATATYPE, H5E_CANTGET, FAIL, "can't check if reference data is 'nil'")
 
-                    if(dst_copy && (src->shared->u.atomic.u.r.loc == H5T_LOC_DISK)) {
-                        H5MM_memcpy(conv_buf, s, buf_size);
-                    } else {
-                        /* Read reference */
-                        if(src->shared->u.atomic.u.r.cls->read(
+                    if(is_nil) {
+
+                        /* Write "nil" sequence to destination location */
+                        if((*(dst->shared->u.atomic.u.r.cls->setnull))(dst->shared->u.atomic.u.r.file, d, b) < 0)
+                            HGOTO_ERROR(H5E_DATATYPE, H5E_WRITEERROR, FAIL, "can't set reference data to 'nil'")
+                    } /* end else-if */
+                    else {
+                        /* Get size of references */
+                        if(0 == (buf_size = src->shared->u.atomic.u.r.cls->getsize(
                             src->shared->u.atomic.u.r.file, s, src->shared->size,
-                            dst->shared->u.atomic.u.r.file, conv_buf, buf_size) < 0)
-                            HGOTO_ERROR(H5E_DATATYPE, H5E_READERROR, FAIL, "can't read reference data")
-                    }
+                            dst->shared->u.atomic.u.r.file, &dst_copy)))
+                            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "incorrect size")
+
+                        /* Check if conversion buffer is large enough, resize if necessary. */
+                        if(conv_buf_size < buf_size) {
+                            conv_buf_size = buf_size;
+                            if(NULL == (conv_buf = H5FL_BLK_REALLOC(ref_seq, conv_buf, conv_buf_size)))
+                                HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for type conversion")
+                            HDmemset(conv_buf, 0, conv_buf_size);
+                        } /* end if */
 
-                    if(dst_copy && (dst->shared->u.atomic.u.r.loc == H5T_LOC_DISK)) {
-                        H5MM_memcpy(d, conv_buf, buf_size);
-                    } else {
-                        /* Write reference to destination location */
-                        if(dst->shared->u.atomic.u.r.cls->write(
-                            src->shared->u.atomic.u.r.file, conv_buf, buf_size, src->shared->u.atomic.u.r.rtype,
-                            dst->shared->u.atomic.u.r.file, d, dst->shared->size, b) < 0)
-                            HGOTO_ERROR(H5E_DATATYPE, H5E_WRITEERROR, FAIL, "can't write reference data")
+                        if(dst_copy && (src->shared->u.atomic.u.r.loc == H5T_LOC_DISK)) {
+                            H5MM_memcpy(conv_buf, s, buf_size);
+                        } else {
+                            /* Read reference */
+                            if(src->shared->u.atomic.u.r.cls->read(
+                                src->shared->u.atomic.u.r.file, s, src->shared->size,
+                                dst->shared->u.atomic.u.r.file, conv_buf, buf_size) < 0)
+                                HGOTO_ERROR(H5E_DATATYPE, H5E_READERROR, FAIL, "can't read reference data")
+                        }
+
+                        if(dst_copy && (dst->shared->u.atomic.u.r.loc == H5T_LOC_DISK)) {
+                            H5MM_memcpy(d, conv_buf, buf_size);
+                        } else {
+                            /* Write reference to destination location */
+                            if(dst->shared->u.atomic.u.r.cls->write(
+                                src->shared->u.atomic.u.r.file, conv_buf, buf_size, src->shared->u.atomic.u.r.rtype,
+                                dst->shared->u.atomic.u.r.file, d, dst->shared->size, b) < 0)
+                                HGOTO_ERROR(H5E_DATATYPE, H5E_WRITEERROR, FAIL, "can't write reference data")
+                        }
                     }
 
                     /* Advance pointers */
diff --git a/src/H5Tpkg.h b/src/H5Tpkg.h
index 1dbc229..39bff15 100644
--- a/src/H5Tpkg.h
+++ b/src/H5Tpkg.h
@@ -182,11 +182,15 @@ struct H5T_path_t {
 };
 
 /* Reference function pointers */
+typedef herr_t (*H5T_ref_isnullfunc_t)(const H5VL_object_t *file, const void *src_buf, hbool_t *isnull);
+typedef herr_t (*H5T_ref_setnullfunc_t)(H5VL_object_t *file, void *dst_buf, void *bg_buf);
 typedef size_t (*H5T_ref_getsizefunc_t)(H5VL_object_t *src_file, const void *src_buf, size_t src_size, H5VL_object_t *dst_file, hbool_t *dst_copy);
 typedef herr_t (*H5T_ref_readfunc_t)(H5VL_object_t *src_file, const void *src_buf, size_t src_size, H5VL_object_t *dst_file, void *dst_buf, size_t dst_size);
 typedef herr_t (*H5T_ref_writefunc_t)(H5VL_object_t *src_file, const void *src_buf, size_t src_size, H5R_type_t src_type, H5VL_object_t *dst_file, void *dst_buf, size_t dst_size, void *bg_buf);
 
 typedef struct H5T_ref_class_t {
+    H5T_ref_isnullfunc_t    isnull;     /* check if reference value is NIL */
+    H5T_ref_setnullfunc_t   setnull;    /* set a reference value to NIL */
     H5T_ref_getsizefunc_t   getsize;    /* get reference size (bytes)   */
     H5T_ref_readfunc_t      read;       /* read reference into buffer   */
     H5T_ref_writefunc_t     write;      /* write reference from buffer  */
diff --git a/src/H5Tprivate.h b/src/H5Tprivate.h
index 86bc174..d8e98af 100644
--- a/src/H5Tprivate.h
+++ b/src/H5Tprivate.h
@@ -109,7 +109,7 @@ H5_DLLVAR H5T_order_t H5T_native_order_g;
 
 /* Private functions */
 H5_DLL herr_t H5T_init(void);
-H5_DLL H5T_t *H5T_copy(const H5T_t *old_dt, H5T_copy_t method);
+H5_DLL H5T_t *H5T_copy(H5T_t *old_dt, H5T_copy_t method);
 H5_DLL herr_t H5T_lock(H5T_t *dt, hbool_t immutable);
 H5_DLL herr_t H5T_close(H5T_t *dt);
 H5_DLL herr_t H5T_close_real(H5T_t *dt);
diff --git a/src/H5Tref.c b/src/H5Tref.c
index b1bc9e8..6f21363 100644
--- a/src/H5Tref.c
+++ b/src/H5Tref.c
@@ -54,18 +54,24 @@ struct H5Tref_dsetreg {
 /* Local Prototypes */
 /********************/
 
+static herr_t H5T__ref_mem_isnull(const H5VL_object_t *src_file, const void *src_buf, hbool_t *isnull);
+static herr_t H5T__ref_mem_setnull(H5VL_object_t *dst_file, void *dst_buf, void *bg_buf);
 static size_t H5T__ref_mem_getsize(H5VL_object_t *src_file, const void *src_buf, size_t src_size, H5VL_object_t *dst_file, hbool_t *dst_copy);
 static herr_t H5T__ref_mem_read(H5VL_object_t *src_file, const void *src_buf, size_t src_size, H5VL_object_t *dst_file, void *dst_buf, size_t dst_size);
 static herr_t H5T__ref_mem_write(H5VL_object_t *src_file, const void *src_buf, size_t src_size, H5R_type_t src_type, H5VL_object_t *dst_file, void *dst_buf, size_t dst_size, void *bg_buf);
 
+static herr_t H5T__ref_disk_isnull(const H5VL_object_t *src_file, const void *src_buf, hbool_t *isnull);
+static herr_t H5T__ref_disk_setnull(H5VL_object_t *dst_file, void *dst_buf, void *bg_buf);
 static size_t H5T__ref_disk_getsize(H5VL_object_t *src_file, const void *src_buf, size_t src_size, H5VL_object_t *dst_file, hbool_t *dst_copy);
 static herr_t H5T__ref_disk_read(H5VL_object_t *src_file, const void *src_buf, size_t src_size, H5VL_object_t *dst_file, void *dst_buf, size_t dst_size);
 static herr_t H5T__ref_disk_write(H5VL_object_t *src_file, const void *src_buf, size_t src_size, H5R_type_t src_type, H5VL_object_t *dst_file, void *dst_buf, size_t dst_size, void *bg_buf);
 
 /* For compatibility */
+static herr_t H5T__ref_obj_disk_isnull(const H5VL_object_t *src_file, const void *src_buf, hbool_t *isnull);
 static size_t H5T__ref_obj_disk_getsize(H5VL_object_t *src_file, const void *src_buf, size_t src_size, H5VL_object_t *dst_file, hbool_t *dst_copy);
 static herr_t H5T__ref_obj_disk_read(H5VL_object_t *src_file, const void *src_buf, size_t src_size, H5VL_object_t *dst_file, void *dst_buf, size_t dst_size);
 
+static herr_t H5T__ref_dsetreg_disk_isnull(const H5VL_object_t *src_file, const void *src_buf, hbool_t *isnull);
 static size_t H5T__ref_dsetreg_disk_getsize(H5VL_object_t *src_file, const void *src_buf, size_t src_size, H5VL_object_t *dst_file, hbool_t *dst_copy);
 static herr_t H5T__ref_dsetreg_disk_read(H5VL_object_t *src_file, const void *src_buf, size_t src_size, H5VL_object_t *dst_file, void *dst_buf, size_t dst_size);
 
@@ -75,24 +81,32 @@ static herr_t H5T__ref_dsetreg_disk_read(H5VL_object_t *src_file, const void *sr
 
 /* Class for reference in memory */
 static const H5T_ref_class_t H5T_ref_mem_g = {
+    H5T__ref_mem_isnull,            /* 'isnull' */
+    H5T__ref_mem_setnull,           /* 'setnull' */
     H5T__ref_mem_getsize,           /* 'getsize' */
     H5T__ref_mem_read,              /* 'read' */
     H5T__ref_mem_write              /* 'write' */
 };
 
 static const H5T_ref_class_t H5T_ref_disk_g = {
+    H5T__ref_disk_isnull,           /* 'isnull' */
+    H5T__ref_disk_setnull,          /* 'setnull' */
     H5T__ref_disk_getsize,          /* 'getsize' */
     H5T__ref_disk_read,             /* 'read' */
     H5T__ref_disk_write             /* 'write' */
 };
 
 static const H5T_ref_class_t H5T_ref_obj_disk_g = {
+    H5T__ref_obj_disk_isnull,       /* 'isnull' */
+    NULL,                           /* 'setnull' */
     H5T__ref_obj_disk_getsize,      /* 'getsize' */
     H5T__ref_obj_disk_read,         /* 'read' */
     NULL                            /* 'write' */
 };
 
 static const H5T_ref_class_t H5T_ref_dsetreg_disk_g = {
+    H5T__ref_dsetreg_disk_isnull,   /* 'isnull' */
+    NULL,                           /* 'setnull' */
     H5T__ref_dsetreg_disk_getsize,  /* 'getsize' */
     H5T__ref_dsetreg_disk_read,     /* 'read' */
     NULL                            /* 'write' */
@@ -268,6 +282,57 @@ done:
 
 
 /*-------------------------------------------------------------------------
+ * Function:    H5T__ref_mem_isnull
+ *
+ * Purpose: Check if it's a NULL / uninitialized reference.
+ *
+ * Return:  Non-negative on success/Negative on failure
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5T__ref_mem_isnull(const H5VL_object_t H5_ATTR_UNUSED *src_file,
+    const void *src_buf, hbool_t *isnull)
+{
+    const unsigned char zeros[H5T_REF_MEM_SIZE] = { 0 };
+    herr_t ret_value = SUCCEED;
+
+    FUNC_ENTER_STATIC_NOERR
+
+    /* Check parameters */
+    HDassert(src_buf);
+    HDassert(isnull);
+
+    *isnull = (0 == HDmemcmp(src_buf, zeros, H5T_REF_MEM_SIZE)) ? TRUE : FALSE;
+
+    FUNC_LEAVE_NOAPI(ret_value)
+}   /* end H5T__ref_mem_isnull() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5T__ref_mem_setnull
+ *
+ * Purpose: Set a reference as NULL / uninitialized.
+ *
+ * Return:  Non-negative on success/Negative on failure
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5T__ref_mem_setnull(H5VL_object_t H5_ATTR_UNUSED *dst_file, void *dst_buf,
+    H5_ATTR_UNUSED void *bg_buf)
+{
+    herr_t ret_value = SUCCEED;
+
+    FUNC_ENTER_STATIC_NOERR
+
+    HDmemset(dst_buf, 0, H5T_REF_MEM_SIZE);
+
+    FUNC_LEAVE_NOAPI(ret_value)
+}   /* end H5T__ref_mem_setnull() */
+
+
+/*-------------------------------------------------------------------------
  * Function:	H5T__ref_mem_getsize
  *
  * Purpose:	Retrieves the size of a memory based reference.
@@ -280,10 +345,12 @@ static size_t
 H5T__ref_mem_getsize(H5VL_object_t H5_ATTR_UNUSED *src_file, const void *src_buf,
     size_t H5_ATTR_UNUSED src_size, H5VL_object_t *dst_file, hbool_t *dst_copy)
 {
-    H5F_t *src_f;
-    H5F_t *dst_f;
     H5VL_object_t *vol_obj = NULL;
     const H5R_ref_priv_t *src_ref = (const H5R_ref_priv_t *)src_buf;
+    hbool_t files_equal = FALSE;
+    char file_name_buf_static[256];
+    char *file_name_buf_dyn = NULL;
+    ssize_t file_name_len;
     unsigned flags = 0;
     size_t ret_value = 0;
 
@@ -296,27 +363,43 @@ H5T__ref_mem_getsize(H5VL_object_t H5_ATTR_UNUSED *src_file, const void *src_buf
     if(NULL == (vol_obj = H5VL_vol_object(src_ref->loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, 0, "invalid location identifier")
 
-    /* We should assert here that the terminal connector is H5VL_NATIVE once
-     * there is a facility to do so -NAF 2019/10/30 */
-
-    /* Retrieve files from VOL objects */
-    if(NULL == (src_f = (H5F_t *)H5VL_object_data(vol_obj)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, 0, "invalid VOL object")
-    if(NULL == (dst_f = (H5F_t *)H5VL_object_data(dst_file)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, 0, "invalid VOL object")
-
     /* Set external flag if referenced file is not destination file */
-    flags |= (src_f->shared != dst_f->shared) ? H5R_IS_EXTERNAL : 0;
+    if(H5VL_file_specific(vol_obj, H5VL_FILE_IS_EQUAL, H5P_DATASET_XFER_DEFAULT, NULL, dst_file, &files_equal) < 0)
+        HGOTO_ERROR(H5E_REFERENCE, H5E_CANTCOMPARE, 0, "can't check if files are equal")
+    flags |= !files_equal ? H5R_IS_EXTERNAL : 0;
 
     /* Force re-calculating encoding size if any flags are set */
     if(flags || !src_ref->encode_size) {
         /* Pass the correct encoding version for the selection depending on the
          * file libver bounds, this is later retrieved in H5S hyper encode */
-        if(src_ref->type == (int8_t)H5R_DATASET_REGION2)
-            H5CX_set_libver_bounds(dst_f);
+        if(src_ref->type == (int8_t)H5R_DATASET_REGION2) {
+            /* Temporary hack to check if this is the native connector.  We need to
+             * add a way to check if the terminal connector is native.  For now this
+             * will break passthroughs, but it's needed for other VOL connectors to
+             * work.  -NAF */
+            if(dst_file->connector->cls->value == H5VL_NATIVE_VALUE) {
+                H5F_t *dst_f;
+
+                if(NULL == (dst_f = (H5F_t *)H5VL_object_data(dst_file)))
+                    HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, 0, "invalid VOL object")
+                H5CX_set_libver_bounds(dst_f);
+            } /* end if */
+            else
+                H5CX_set_libver_bounds(NULL);
+        } /* end if */
+
+        /* Get file name */
+        if(H5VL_file_get(vol_obj, H5VL_FILE_GET_NAME, H5P_DATASET_XFER_DEFAULT, NULL, H5I_FILE, sizeof(file_name_buf_static), file_name_buf_static, &file_name_len) < 0)
+            HGOTO_ERROR(H5E_REFERENCE, H5E_CANTGET, 0, "can't get file name")
+        if(file_name_len >= (ssize_t)sizeof(file_name_buf_static)) {
+            if(NULL == (file_name_buf_dyn = (char *)H5MM_malloc((size_t)file_name_len + 1)))
+                HGOTO_ERROR(H5E_RESOURCE, H5E_CANTALLOC, 0, "can't allocate space for file name")
+            if(H5VL_file_get(vol_obj, H5VL_FILE_GET_NAME, H5P_DATASET_XFER_DEFAULT, NULL, H5I_FILE, (size_t)file_name_len + 1, file_name_buf_dyn, &file_name_len) < 0)
+                HGOTO_ERROR(H5E_REFERENCE, H5E_CANTGET, 0, "can't get file name")
+        } /* end if */
 
         /* Determine encoding size */
-        if(H5R__encode(H5F_ACTUAL_NAME(src_f), src_ref, NULL, &ret_value, flags) < 0)
+        if(H5R__encode(file_name_buf_dyn ? file_name_buf_dyn : file_name_buf_static, src_ref, NULL, &ret_value, flags) < 0)
             HGOTO_ERROR(H5E_REFERENCE, H5E_CANTENCODE, 0, "unable to determine encoding size")
     } else {
         /* Can do a direct copy and skip blob decoding */
@@ -328,6 +411,8 @@ H5T__ref_mem_getsize(H5VL_object_t H5_ATTR_UNUSED *src_file, const void *src_buf
     }
 
 done:
+    H5MM_xfree(file_name_buf_dyn);
+
     FUNC_LEAVE_NOAPI(ret_value)
 }   /* end H5T__ref_mem_getsize() */
 
@@ -346,10 +431,12 @@ H5T__ref_mem_read(H5VL_object_t H5_ATTR_UNUSED *src_file, const void *src_buf,
     size_t H5_ATTR_UNUSED src_size, H5VL_object_t *dst_file, void *dst_buf,
     size_t dst_size)
 {
-    H5F_t *src_f;
-    H5F_t *dst_f;
     H5VL_object_t *vol_obj = NULL;
     const H5R_ref_priv_t *src_ref = (const H5R_ref_priv_t *)src_buf;
+    hbool_t files_equal = FALSE;
+    char file_name_buf_static[256];
+    char *file_name_buf_dyn = NULL;
+    ssize_t file_name_len;
     unsigned flags = 0;
     herr_t ret_value = SUCCEED;
 
@@ -365,28 +452,46 @@ H5T__ref_mem_read(H5VL_object_t H5_ATTR_UNUSED *src_file, const void *src_buf,
     if(NULL == (vol_obj = H5VL_vol_object(src_ref->loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, 0, "invalid location identifier")
 
-    /* We should assert here that the terminal connector is H5VL_NATIVE once
-     * there is a facility to do so -NAF 2019/10/30 */
-
-    /* Retrieve files from VOL objects */
-    if(NULL == (src_f = (H5F_t *)H5VL_object_data(vol_obj)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, 0, "invalid VOL object")
-    if(NULL == (dst_f = (H5F_t *)H5VL_object_data(dst_file)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, 0, "invalid VOL object")
-
     /* Set external flag if referenced file is not destination file */
-    flags |= (src_f->shared != dst_f->shared) ? H5R_IS_EXTERNAL : 0;
+    if(H5VL_file_specific(vol_obj, H5VL_FILE_IS_EQUAL, H5P_DATASET_XFER_DEFAULT, NULL, dst_file, &files_equal) < 0)
+        HGOTO_ERROR(H5E_REFERENCE, H5E_CANTCOMPARE, FAIL, "can't check if files are equal")
+    flags |= !files_equal ? H5R_IS_EXTERNAL : 0;
 
     /* Pass the correct encoding version for the selection depending on the
      * file libver bounds, this is later retrieved in H5S hyper encode */
-    if(src_ref->type == (int8_t)H5R_DATASET_REGION2)
-        H5CX_set_libver_bounds(dst_f);
+    if(src_ref->type == (int8_t)H5R_DATASET_REGION2) {
+        /* Temporary hack to check if this is the native connector.  We need to
+         * add a way to check if the terminal connector is native.  For now this
+         * will break passthroughs, but it's needed for other VOL connectors to
+         * work.  -NAF */
+        if(dst_file->connector->cls->value == H5VL_NATIVE_VALUE) {
+            H5F_t *dst_f;
+
+            if(NULL == (dst_f = (H5F_t *)H5VL_object_data(dst_file)))
+                HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, 0, "invalid VOL object")
+            H5CX_set_libver_bounds(dst_f);
+        } /* end if */
+        else
+            H5CX_set_libver_bounds(NULL);
+    } /* end if */
+
+    /* Get file name */
+    if(H5VL_file_get(vol_obj, H5VL_FILE_GET_NAME, H5P_DATASET_XFER_DEFAULT, NULL, H5I_FILE, sizeof(file_name_buf_static), file_name_buf_static, &file_name_len) < 0)
+        HGOTO_ERROR(H5E_REFERENCE, H5E_CANTGET, 0, "can't get file name")
+    if(file_name_len >= (ssize_t)sizeof(file_name_buf_static)) {
+        if(NULL == (file_name_buf_dyn = (char *)H5MM_malloc((size_t)file_name_len + 1)))
+            HGOTO_ERROR(H5E_RESOURCE, H5E_CANTALLOC, 0, "can't allocate space for file name")
+        if(H5VL_file_get(vol_obj, H5VL_FILE_GET_NAME, H5P_DATASET_XFER_DEFAULT, NULL, H5I_FILE, (size_t)file_name_len + 1, file_name_buf_dyn, &file_name_len) < 0)
+            HGOTO_ERROR(H5E_REFERENCE, H5E_CANTGET, 0, "can't get file name")
+    } /* end if */
 
     /* Encode reference */
-    if(H5R__encode(H5F_ACTUAL_NAME(src_f), src_ref, (unsigned char *)dst_buf, &dst_size, flags) < 0)
+    if(H5R__encode(file_name_buf_dyn ? file_name_buf_dyn : file_name_buf_static, src_ref, (unsigned char *)dst_buf, &dst_size, flags) < 0)
         HGOTO_ERROR(H5E_REFERENCE, H5E_CANTENCODE, FAIL, "Cannot encode reference")
 
 done:
+    H5MM_xfree(file_name_buf_dyn);
+
     FUNC_LEAVE_NOAPI(ret_value)
 }   /* end H5T__ref_mem_read() */
 
@@ -468,7 +573,7 @@ H5T__ref_mem_write(H5VL_object_t *src_file, const void *src_buf, size_t src_size
     /* If no filename set, this is not an external reference */
     if(NULL == H5R_REF_FILENAME(dst_ref)) {
         /* TODO temporary hack to retrieve file object */
-        if((file_id = H5F__get_file_id(src_f, FALSE)) < 0)
+        if((file_id = H5F_get_file_id(src_file, H5I_FILE, FALSE)) < 0)
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a file or file object")
 
         /* Attach loc ID to reference and hold reference to it */
@@ -484,6 +589,96 @@ done:
 
 
 /*-------------------------------------------------------------------------
+ * Function:    H5T__ref_disk_isnull
+ *
+ * Purpose: Check if it's a NULL / uninitialized reference.
+ *
+ * Return:  Non-negative on success/Negative on failure
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5T__ref_disk_isnull(const H5VL_object_t *src_file, const void *src_buf,
+    hbool_t *isnull)
+{
+    const uint8_t *p = (const uint8_t *)src_buf;
+    H5R_type_t ref_type;
+    herr_t ret_value = SUCCEED;
+
+    FUNC_ENTER_STATIC
+
+    /* Check parameters */
+    HDassert(src_file);
+    HDassert(src_buf);
+    HDassert(isnull);
+
+    /* Try to check encoded reference type */
+    ref_type = (H5R_type_t)*p++;
+    if(ref_type) {
+        /* This is a valid reference */
+        *isnull = FALSE;
+    } else {
+        /* Skip the size / header */
+        p = (const uint8_t *)src_buf + H5R_ENCODE_HEADER_SIZE + H5_SIZEOF_UINT32_T;
+
+        /* Check if blob ID is "nil" */
+        if(H5VL_blob_specific(src_file, (void *)p, H5VL_BLOB_ISNULL, isnull) < 0)
+            HGOTO_ERROR(H5E_DATATYPE, H5E_CANTGET, FAIL, "unable to check if a blob ID is 'nil'")
+    }
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+}   /* end H5T__ref_disk_isnull() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5T__ref_disk_setnull
+ *
+ * Purpose: Set a reference as NULL / uninitialized.
+ *
+ * Return:  Non-negative on success/Negative on failure
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5T__ref_disk_setnull(H5VL_object_t *dst_file, void *dst_buf, void *bg_buf)
+{
+    uint8_t *q = (uint8_t *)dst_buf;
+    uint8_t *p_bg = (uint8_t *)bg_buf;
+    herr_t ret_value = SUCCEED;
+
+    FUNC_ENTER_STATIC
+
+    HDassert(dst_file);
+    HDassert(dst_buf);
+
+    /* TODO Should get rid of bg stuff */
+    if(p_bg) {
+        /* Skip the size / header */
+        p_bg += (H5_SIZEOF_UINT32_T + H5R_ENCODE_HEADER_SIZE);
+
+        /* Remove blob for old data */
+        if(H5VL_blob_specific(dst_file, (void *)p_bg, H5VL_BLOB_DELETE) < 0)
+            HGOTO_ERROR(H5E_DATATYPE, H5E_CANTREMOVE, FAIL, "unable to delete blob")
+    } /* end if */
+
+    /* Copy header manually so that it does not get encoded into the blob */
+    HDmemset(q, 0, H5R_ENCODE_HEADER_SIZE);
+    q += H5R_ENCODE_HEADER_SIZE;
+
+    /* Set the size */
+    UINT32ENCODE(q, 0);
+
+    /* Set blob ID to "nil" */
+    if(H5VL_blob_specific(dst_file, q, H5VL_BLOB_SETNULL) < 0)
+        HGOTO_ERROR(H5E_DATATYPE, H5E_CANTSET, FAIL, "unable to set a blob ID to 'nil'")
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+}   /* end H5T__ref_disk_setnull() */
+
+
+/*-------------------------------------------------------------------------
  * Function:	H5T__ref_disk_getsize
  *
  * Purpose:	Retrieves the length of a disk based reference.
@@ -562,7 +757,7 @@ H5T__ref_disk_read(H5VL_object_t *src_file, const void *src_buf, size_t src_size
     q += H5R_ENCODE_HEADER_SIZE;
     blob_size -= H5R_ENCODE_HEADER_SIZE;
 
-    /* Skip the length of the sequence */
+    /* Skip the size */
     p += H5_SIZEOF_UINT32_T;
     HDassert(src_size > (H5R_ENCODE_HEADER_SIZE + H5_SIZEOF_UINT32_T));
 
@@ -606,10 +801,10 @@ H5T__ref_disk_write(H5VL_object_t H5_ATTR_UNUSED *src_file, const void *src_buf,
     if(p_bg) {
         size_t p_buf_size_left = dst_size;
 
-        /* Skip the length of the reference */
-        p_bg += H5_SIZEOF_UINT32_T;
-        HDassert(p_buf_size_left > H5_SIZEOF_UINT32_T);
-        p_buf_size_left -= H5_SIZEOF_UINT32_T;
+        /* Skip the size / header */
+        p_bg += (H5_SIZEOF_UINT32_T + H5R_ENCODE_HEADER_SIZE);
+        HDassert(p_buf_size_left > (H5_SIZEOF_UINT32_T + H5R_ENCODE_HEADER_SIZE));
+        p_buf_size_left -= (H5_SIZEOF_UINT32_T + H5R_ENCODE_HEADER_SIZE);
 
         /* Remove blob for old data */
         if(H5VL_blob_specific(dst_file, (void *)p_bg, H5VL_BLOB_DELETE) < 0)
@@ -638,6 +833,48 @@ done:
 
 
 /*-------------------------------------------------------------------------
+ * Function:    H5T__ref_obj_disk_isnull
+ *
+ * Purpose: Check if it's a NULL / uninitialized reference.
+ *
+ * Return:  Non-negative on success/Negative on failure
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t H5T__ref_obj_disk_isnull(const H5VL_object_t *src_file,
+    const void *src_buf, hbool_t *isnull)
+{
+    H5F_t *src_f;
+    const uint8_t *p = (const uint8_t *)src_buf;
+    haddr_t addr;
+    herr_t ret_value = SUCCEED;
+
+    FUNC_ENTER_STATIC
+
+    /* Check parameters */
+    HDassert(src_file);
+    HDassert(src_buf);
+    HDassert(isnull);
+
+    /* We should assert here that the terminal connector is H5VL_NATIVE once
+     * there is a facility to do so -NAF 2019/10/30 */
+
+    /* Retrieve file from VOL object */
+    if(NULL == (src_f = (H5F_t *)H5VL_object_data(src_file)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid VOL object")
+
+    /* Get the object address */
+    H5F_addr_decode(src_f, &p, &addr);
+
+    /* Check if heap address is 'nil' */
+    *isnull = (addr == 0) ? TRUE : FALSE;
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+}   /* end H5T__ref_obj_disk_isnull() */
+
+
+/*-------------------------------------------------------------------------
  * Function:    H5T__ref_obj_disk_getsize
  *
  * Purpose: Retrieves the length of a disk based reference.
@@ -718,6 +955,49 @@ done:
 
 
 /*-------------------------------------------------------------------------
+ * Function:    H5T__ref_dsetreg_disk_isnull
+ *
+ * Purpose: Check if it's a NULL / uninitialized reference.
+ *
+ * Return:  Non-negative on success/Negative on failure
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5T__ref_dsetreg_disk_isnull(const H5VL_object_t *src_file, const void *src_buf,
+    hbool_t *isnull)
+{
+    H5F_t *src_f;
+    const uint8_t *p = (const uint8_t *)src_buf;
+    haddr_t addr;
+    herr_t ret_value = SUCCEED;
+
+    FUNC_ENTER_STATIC
+
+    /* Check parameters */
+    HDassert(src_file);
+    HDassert(src_buf);
+    HDassert(isnull);
+
+    /* We should assert here that the terminal connector is H5VL_NATIVE once
+     * there is a facility to do so -NAF 2019/10/30 */
+
+    /* Retrieve file from VOL object */
+    if(NULL == (src_f = (H5F_t *)H5VL_object_data(src_file)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid VOL object")
+
+    /* Get the heap address */
+    H5F_addr_decode(src_f, &p, &addr);
+
+    /* Check if heap address is 'nil' */
+    *isnull = (addr == 0) ? TRUE : FALSE;
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+}   /* end H5T__ref_dsetreg_disk_isnull() */
+
+
+/*-------------------------------------------------------------------------
  * Function:    H5T__ref_dsetreg_disk_getsize
  *
  * Purpose: Retrieves the length of a disk based reference.
@@ -727,28 +1007,28 @@ done:
  *-------------------------------------------------------------------------
  */
 static size_t
-H5T__ref_dsetreg_disk_getsize(H5VL_object_t H5_ATTR_UNUSED *file,
-    const void H5_ATTR_UNUSED *buf, size_t H5_ATTR_UNUSED buf_size,
+H5T__ref_dsetreg_disk_getsize(H5VL_object_t H5_ATTR_UNUSED *src_file,
+    const void H5_ATTR_UNUSED *src_buf, size_t H5_ATTR_UNUSED src_size,
     H5VL_object_t H5_ATTR_UNUSED *dst_file, hbool_t H5_ATTR_UNUSED *dst_copy)
 {
     size_t ret_value = sizeof(struct H5Tref_dsetreg);
 
     FUNC_ENTER_STATIC
 
-    HDassert(buf);
+    HDassert(src_buf);
 
 #ifndef NDEBUG
     {
-        H5F_t *f;
+        H5F_t *src_f;
 
         /* We should assert here that the terminal connector is H5VL_NATIVE once
          * there is a facility to do so -NAF 2019/10/30 */
 
         /* Retrieve file from VOL object */
-        if(NULL == (f = (H5F_t *)H5VL_object_data(file)))
+        if(NULL == (src_f = (H5F_t *)H5VL_object_data(src_file)))
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, 0, "invalid VOL object")
 
-        HDassert(buf_size == H5T_REF_DSETREG_DISK_SIZE(f));
+        HDassert(src_size == H5T_REF_DSETREG_DISK_SIZE(src_f));
     } /* end block */
 #endif /* NDEBUG */
 
@@ -827,3 +1107,4 @@ H5T_ref_reclaim(void *elem, const H5T_t *dt)
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5T_ref_reclaim() */
+
diff --git a/src/H5VLcallback.c b/src/H5VLcallback.c
index 8d7368b..77df207 100644
--- a/src/H5VLcallback.c
+++ b/src/H5VLcallback.c
@@ -101,6 +101,8 @@ static void * H5VL__file_open(const H5VL_class_t *cls, const char *name,
     unsigned flags, hid_t fapl_id, hid_t dxpl_id, void **req);
 static herr_t H5VL__file_get(void *obj, const H5VL_class_t *cls, H5VL_file_get_t get_type, 
     hid_t dxpl_id, void **req, va_list arguments);
+static herr_t H5VL__file_specific_wrap_va_list(void *obj, const H5VL_class_t *cls,
+    H5VL_file_specific_t specific_type,  hid_t dxpl_id, void **req, ...);
 static herr_t H5VL__file_specific(void *obj, const H5VL_class_t *cls, H5VL_file_specific_t specific_type, 
     hid_t dxpl_id, void **req, va_list arguments);
 static herr_t H5VL__file_optional(void *obj, const H5VL_class_t *cls, hid_t dxpl_id,
@@ -2989,6 +2991,43 @@ done:
 
 
 /*-------------------------------------------------------------------------
+ * Function:	H5VL__file_specific_wrap_va_list
+ *
+ * Purpose:     Perform File specific operations through the VOL.  Just
+ *              starts a va_list and passes it to the connector's
+ *              callback.  Needed when the VOL layer needs to replace one
+ *              of the variable arguments.
+ *
+ * Return:      Success:    Non-negative
+ *              Failure:    Negative
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5VL__file_specific_wrap_va_list(void *obj, const H5VL_class_t *cls,
+    H5VL_file_specific_t specific_type,  hid_t dxpl_id, void **req, ...)
+{
+    va_list arguments;                  /* Argument list passed from the API call */
+    herr_t ret_value = SUCCEED;         /* Return value */
+
+    FUNC_ENTER_STATIC
+
+    /* Start access to the varargs, so they are available in all situations below */
+    HDva_start(arguments, req);
+
+    /* Call the corresponding VOL callback */
+    if((cls->file_cls.specific)(obj, specific_type, dxpl_id, req, arguments) < 0)
+        HGOTO_ERROR(H5E_VOL, H5E_CANTOPERATE, FAIL, "file specific failed")
+
+done:
+    /* End access to the va_list */
+    HDva_end(arguments);
+
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5VL__file_specific_wrap_va_list() */
+
+
+/*-------------------------------------------------------------------------
  * Function:	H5VL__file_specific
  *
  * Purpose:	Perform File specific operations through the VOL
@@ -3010,9 +3049,38 @@ H5VL__file_specific(void *obj, const H5VL_class_t *cls, H5VL_file_specific_t spe
     if(NULL == cls->file_cls.specific)
         HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "VOL connector has no 'file specific' method")
 
-    /* Call the corresponding VOL callback */
-    if((cls->file_cls.specific)(obj, specific_type, dxpl_id, req, arguments) < 0)
-        HGOTO_ERROR(H5E_VOL, H5E_CANTOPERATE, FAIL, "file specific failed")
+    /* Special handling for file is equal */
+    if(specific_type == H5VL_FILE_IS_EQUAL) {
+        va_list             tmp_args;       /* Argument list passed from the API call */
+        H5VL_object_t       *vol_obj2;      /* Second VOL object */
+        hbool_t             *is_equal;      /* Output variable */
+        int                 cmp_value;      /* Comparison result */
+
+        /* Get parameters */
+        HDva_copy(tmp_args, arguments);
+        vol_obj2 = HDva_arg(tmp_args, H5VL_object_t *);
+        is_equal = HDva_arg(tmp_args, hbool_t *);
+        HDva_end(tmp_args);
+
+        HDassert(vol_obj2);
+
+        /* Compare connector classes */
+        if(H5VL_cmp_connector_cls(&cmp_value, cls, vol_obj2->connector->cls) < 0)
+            HGOTO_ERROR(H5E_VOL, H5E_CANTCOMPARE, FAIL, "can't compare connector classes")
+
+        /* If the classes are different the files are different */
+        if(cmp_value)
+            *is_equal = FALSE;
+        else
+            /* Make callback (need to extract data from vol_obj2 and redo the
+             * va_list) */
+            if(H5VL__file_specific_wrap_va_list(obj, cls, specific_type, dxpl_id, req, vol_obj2->data, is_equal) < 0)
+                HGOTO_ERROR(H5E_VOL, H5E_CANTOPERATE, FAIL, "file specific failed")
+    } /* end if */
+    else
+        /* Call the corresponding VOL callback */
+        if((cls->file_cls.specific)(obj, specific_type, dxpl_id, req, arguments) < 0)
+            HGOTO_ERROR(H5E_VOL, H5E_CANTOPERATE, FAIL, "file specific failed")
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
diff --git a/src/H5VLconnector.h b/src/H5VLconnector.h
index 13cb2b5..f0925bf 100644
--- a/src/H5VLconnector.h
+++ b/src/H5VLconnector.h
@@ -122,7 +122,8 @@ typedef enum H5VL_file_specific_t {
     H5VL_FILE_MOUNT,                        /* Mount a file                     */
     H5VL_FILE_UNMOUNT,                      /* Unmount a file                   */
     H5VL_FILE_IS_ACCESSIBLE,                /* Check if a file is accessible    */
-    H5VL_FILE_DELETE                        /* Delete a file                    */
+    H5VL_FILE_DELETE,                       /* Delete a file                    */
+    H5VL_FILE_IS_EQUAL                      /* Check if two files are the same  */
 } H5VL_file_specific_t;
 
 /* types for group GET callback */
@@ -160,6 +161,7 @@ typedef enum H5VL_link_specific_t {
 
 /* types for object GET callback */
 typedef enum H5VL_object_get_t {
+    H5VL_OBJECT_GET_FILE,              /* object file                       */
     H5VL_OBJECT_GET_NAME,              /* object name                       */
     H5VL_OBJECT_GET_TYPE               /* object type                       */
 } H5VL_object_get_t;
diff --git a/src/H5VLint.c b/src/H5VLint.c
index 733a2b5..284b266 100644
--- a/src/H5VLint.c
+++ b/src/H5VLint.c
@@ -1639,6 +1639,12 @@ H5VL_cmp_connector_cls(int *cmp_value, const H5VL_class_t *cls1, const H5VL_clas
     HDassert(cls1);
     HDassert(cls2);
 
+    /* If the pointers are the same the classes are the same */
+    if(cls1 == cls2) {
+        *cmp_value = 0;
+        HGOTO_DONE(SUCCEED);
+    } /* end if */
+
     /* Compare connector "values" */
     if(cls1->value < cls2->value) {
         *cmp_value = -1;
diff --git a/src/H5VLnative.h b/src/H5VLnative.h
index 5b51e66..73cec8d 100644
--- a/src/H5VLnative.h
+++ b/src/H5VLnative.h
@@ -57,25 +57,24 @@ typedef int H5VL_native_file_optional_t;
 #define H5VL_NATIVE_FILE_GET_MDC_SIZE                   7   /* H5Fget_mdc_size                      */
 #define H5VL_NATIVE_FILE_GET_SIZE                       8   /* H5Fget_filesize                      */
 #define H5VL_NATIVE_FILE_GET_VFD_HANDLE                 9   /* H5Fget_vfd_handle                    */
-#define H5VL_NATIVE_FILE_GET_FILE_ID                    10  /* H5Fget_file_id                       */
-#define H5VL_NATIVE_FILE_RESET_MDC_HIT_RATE             11  /* H5Freset_mdc_hit_rate_stats          */
-#define H5VL_NATIVE_FILE_SET_MDC_CONFIG                 12  /* H5Fset_mdc_config                    */
-#define H5VL_NATIVE_FILE_GET_METADATA_READ_RETRY_INFO   13  /* H5Fget_metadata_read_retry_info      */
-#define H5VL_NATIVE_FILE_START_SWMR_WRITE               14  /* H5Fstart_swmr_write                  */
-#define H5VL_NATIVE_FILE_START_MDC_LOGGING              15  /* H5Fstart_mdc_logging                 */
-#define H5VL_NATIVE_FILE_STOP_MDC_LOGGING               16  /* H5Fstop_mdc_logging                  */
-#define H5VL_NATIVE_FILE_GET_MDC_LOGGING_STATUS         17  /* H5Fget_mdc_logging_status            */
-#define H5VL_NATIVE_FILE_FORMAT_CONVERT                 18  /* H5Fformat_convert                    */
-#define H5VL_NATIVE_FILE_RESET_PAGE_BUFFERING_STATS     19  /* H5Freset_page_buffering_stats        */
-#define H5VL_NATIVE_FILE_GET_PAGE_BUFFERING_STATS       20  /* H5Fget_page_buffering_stats          */
-#define H5VL_NATIVE_FILE_GET_MDC_IMAGE_INFO             21  /* H5Fget_mdc_image_info                */
-#define H5VL_NATIVE_FILE_GET_EOA                        22  /* H5Fget_eoa                           */
-#define H5VL_NATIVE_FILE_INCR_FILESIZE                  23  /* H5Fincrement_filesize                */
-#define H5VL_NATIVE_FILE_SET_LIBVER_BOUNDS              24  /* H5Fset_latest_format/libver_bounds   */
-#define H5VL_NATIVE_FILE_GET_MIN_DSET_OHDR_FLAG         25  /* H5Fget_dset_no_attrs_hint            */
-#define H5VL_NATIVE_FILE_SET_MIN_DSET_OHDR_FLAG         26  /* H5Fset_dset_no_attrs_hint            */
-#define H5VL_NATIVE_FILE_GET_MPI_ATOMICITY              27  /* H5Fget_mpi_atomicity                 */
-#define H5VL_NATIVE_FILE_SET_MPI_ATOMICITY              28  /* H5Fset_mpi_atomicity                 */
+#define H5VL_NATIVE_FILE_RESET_MDC_HIT_RATE             10  /* H5Freset_mdc_hit_rate_stats          */
+#define H5VL_NATIVE_FILE_SET_MDC_CONFIG                 11  /* H5Fset_mdc_config                    */
+#define H5VL_NATIVE_FILE_GET_METADATA_READ_RETRY_INFO   12  /* H5Fget_metadata_read_retry_info      */
+#define H5VL_NATIVE_FILE_START_SWMR_WRITE               13  /* H5Fstart_swmr_write                  */
+#define H5VL_NATIVE_FILE_START_MDC_LOGGING              14  /* H5Fstart_mdc_logging                 */
+#define H5VL_NATIVE_FILE_STOP_MDC_LOGGING               15  /* H5Fstop_mdc_logging                  */
+#define H5VL_NATIVE_FILE_GET_MDC_LOGGING_STATUS         16  /* H5Fget_mdc_logging_status            */
+#define H5VL_NATIVE_FILE_FORMAT_CONVERT                 17  /* H5Fformat_convert                    */
+#define H5VL_NATIVE_FILE_RESET_PAGE_BUFFERING_STATS     18  /* H5Freset_page_buffering_stats        */
+#define H5VL_NATIVE_FILE_GET_PAGE_BUFFERING_STATS       19  /* H5Fget_page_buffering_stats          */
+#define H5VL_NATIVE_FILE_GET_MDC_IMAGE_INFO             20  /* H5Fget_mdc_image_info                */
+#define H5VL_NATIVE_FILE_GET_EOA                        21  /* H5Fget_eoa                           */
+#define H5VL_NATIVE_FILE_INCR_FILESIZE                  22  /* H5Fincrement_filesize                */
+#define H5VL_NATIVE_FILE_SET_LIBVER_BOUNDS              23  /* H5Fset_latest_format/libver_bounds   */
+#define H5VL_NATIVE_FILE_GET_MIN_DSET_OHDR_FLAG         24  /* H5Fget_dset_no_attrs_hint            */
+#define H5VL_NATIVE_FILE_SET_MIN_DSET_OHDR_FLAG         25  /* H5Fset_dset_no_attrs_hint            */
+#define H5VL_NATIVE_FILE_GET_MPI_ATOMICITY              26  /* H5Fget_mpi_atomicity                 */
+#define H5VL_NATIVE_FILE_SET_MPI_ATOMICITY              27  /* H5Fset_mpi_atomicity                 */
 
 /* Typedef and values for native VOL connector group optional VOL operations */
 typedef int H5VL_native_group_optional_t;
diff --git a/src/H5VLnative_file.c b/src/H5VLnative_file.c
index 094722e..588d59f 100644
--- a/src/H5VLnative_file.c
+++ b/src/H5VLnative_file.c
@@ -418,6 +418,19 @@ H5VL__native_file_specific(void *obj, H5VL_file_specific_t specific_type,
                 break;
             }
 
+        /* Check if two files are the same */
+        case H5VL_FILE_IS_EQUAL:
+            {
+                H5F_t *file2 = (H5F_t *)HDva_arg(arguments, void *);
+                hbool_t *is_equal = HDva_arg(arguments, hbool_t *);
+
+                if(!obj || !file2)
+                    *is_equal = FALSE;
+                else
+                    *is_equal = (((H5F_t *)obj)->shared == file2->shared);
+                break;
+            }
+
         default:
             HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "invalid specific operation")
     } /* end switch */
@@ -578,20 +591,6 @@ H5VL__native_file_optional(void *obj, hid_t H5_ATTR_UNUSED dxpl_id, void H5_ATTR
                 break;
             }
 
-        /* H5Iget_file_id */
-        case H5VL_NATIVE_FILE_GET_FILE_ID:
-            {
-                H5I_type_t  type = (H5I_type_t)HDva_arg(arguments, int); /* enum work-around */
-                hbool_t     app_ref = (hbool_t)HDva_arg(arguments, int);
-                hid_t      *file_id = HDva_arg(arguments, hid_t *);
-
-                if(NULL == (f = H5F__get_file(obj, type)))
-                    HGOTO_ERROR(H5E_FILE, H5E_BADTYPE, FAIL, "not a file or file object")
-                if((*file_id = H5F__get_file_id(f, app_ref)) < 0)
-                    HGOTO_ERROR(H5E_FILE, H5E_CANTGET, FAIL, "can't get file ID")
-                break;
-            }
-
         /* H5Fclear_elink_file_cache */
         case H5VL_NATIVE_FILE_CLEAR_ELINK_CACHE:
             {
diff --git a/src/H5VLnative_object.c b/src/H5VLnative_object.c
index 675d8cf..dfa4eab 100644
--- a/src/H5VLnative_object.c
+++ b/src/H5VLnative_object.c
@@ -16,10 +16,11 @@
  */
 
 #define H5O_FRIEND              /* Suppress error about including H5Opkg    */
+#define H5F_FRIEND              /* Suppress error about including H5Fpkg    */
 
 #include "H5private.h"          /* Generic Functions                        */
 #include "H5Eprivate.h"         /* Error handling                           */
-#include "H5Fprivate.h"         /* Files                                    */
+#include "H5Fpkg.h"             /* Files (pkg needed for id_exists)         */
 #include "H5Gprivate.h"         /* Groups                                   */
 #include "H5Iprivate.h"         /* IDs                                      */
 #include "H5Opkg.h"             /* Object headers                           */
@@ -150,6 +151,25 @@ H5VL__native_object_get(void *obj, const H5VL_loc_params_t *loc_params, H5VL_obj
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a file or file object")
 
     switch(get_type) {
+
+        /* Object file */
+        case H5VL_OBJECT_GET_FILE:
+            {
+                void **ret = HDva_arg(arguments, void **);
+
+                if(loc_params->type == H5VL_OBJECT_BY_SELF) {
+                    *ret = (void *)loc.oloc->file;
+
+                    /* TODO we currently need to set id_exists to TRUE because
+                     * the upper layer will create an ID from the returned
+                     * object. In theory this should not be needed and id_exists
+                     * should be removed once the H5Fmount code gets fixed. */
+                    loc.oloc->file->id_exists = TRUE;
+                } else
+                    HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "unknown get_file parameters")
+                break;
+            }
+
         /* Object name */
         case H5VL_OBJECT_GET_NAME:
             {
diff --git a/src/H5trace.c b/src/H5trace.c
index 79dfbc8..65e267e 100644
--- a/src/H5trace.c
+++ b/src/H5trace.c
@@ -3000,6 +3000,9 @@ H5_trace(const double *returning, const char *func, const char *type, ...)
                             H5VL_object_get_t get = (H5VL_object_get_t)HDva_arg(ap, int);
 
                             switch(get) {
+                                case H5VL_OBJECT_GET_FILE:
+                                    HDfprintf(out, "H5VL_OBJECT_GET_FILE");
+                                    break;
                                 case H5VL_OBJECT_GET_NAME:
                                     HDfprintf(out, "H5VL_OBJECT_GET_NAME");
                                     break;
diff --git a/src/libhdf5.settings.in b/src/libhdf5.settings.in
index 0c2be75..1591bed 100644
--- a/src/libhdf5.settings.in
+++ b/src/libhdf5.settings.in
@@ -39,7 +39,7 @@ Languages:
                     H5_CPPFLAGS: @H5_CPPFLAGS@
                     AM_CPPFLAGS: @AM_CPPFLAGS@
                         C Flags: @CFLAGS@
-                     H5 C Flags: @H5_CFLAGS@ @H5_ECFLAGS@
+                     H5 C Flags: @H5_CFLAGS@
                      AM C Flags: @AM_CFLAGS@
                Shared C Library: @enable_shared@
                Static C Library: @enable_static@
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index d3f8ed8..c7a945e 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -16,11 +16,9 @@ set (TEST_LIB_SOURCES
     ${HDF5_TEST_SOURCE_DIR}/cache_common.c
     ${HDF5_TEST_SOURCE_DIR}/external_common.c
     ${HDF5_TEST_SOURCE_DIR}/swmr_common.c
-    ${HDF5_TEST_SOURCE_DIR}/vds_swmr_common.c
 )
 
 set (TEST_LIB_HEADERS
-    ${HDF5_TEST_SOURCE_DIR}/H5srcdir.h
     ${HDF5_TEST_SOURCE_DIR}/h5test.h
     ${HDF5_TEST_SOURCE_DIR}/cache_common.h
     ${HDF5_TEST_SOURCE_DIR}/external_common.h
diff --git a/test/H5srcdir.c b/test/H5srcdir.c
deleted file mode 100644
index 8268d2c..0000000
--- a/test/H5srcdir.c
+++ /dev/null
@@ -1,61 +0,0 @@
-/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
- * Copyright by The HDF Group.                                               *
- * Copyright by the Board of Trustees of the University of Illinois.         *
- * All rights reserved.                                                      *
- *                                                                           *
- * This file is part of HDF5.  The full HDF5 copyright notice, including     *
- * terms governing use, modification, and redistribution, is contained in    *
- * the COPYING file, which can be found at the root of the source code       *
- * distribution tree, or in https://support.hdfgroup.org/ftp/HDF5/releases.  *
- * If you do not have access to either file, you may request a copy from     *
- * help@hdfgroup.org.                                                        *
- * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
-
-#include "H5private.h"
-#include "H5srcdir.h"
-
-/* Buffer to construct path in and return pointer to */
-char srcdir_path[1024] = "";
-
-/* Buffer to construct file in and return pointer to */
-char srcdir_testpath[1024] = "";
-
-/* Just return the srcdir path */
-const char *
-H5_get_srcdir(void)
-{
-    const char *srcdir = HDgetenv("srcdir");
-
-    /* Check for using the srcdir from configure time */
-    if(NULL == srcdir)
-        srcdir = config_srcdir;
-
-    /* Build path to all test files */
-    if((HDstrlen(srcdir) + 2) < sizeof(srcdir_path)) {
-        HDsnprintf(srcdir_path, sizeof(srcdir_path), "%s/", srcdir);
-        return(srcdir_path);
-    } /* end if */
-    else
-        return(NULL);
-} /* end H5_get_srcdir() */
-
-/* Append the test file name to the srcdir path and return the whole string */
-const char *
-H5_get_srcdir_filename(const char *filename)
-{
-    const char *srcdir = H5_get_srcdir();
-
-    /* Check for error */
-    if(NULL == srcdir)
-        return(NULL);
-    else {
-        /* Build path to test file */
-        if((HDstrlen(srcdir) + HDstrlen(filename) + 1) < sizeof(srcdir_testpath)) {
-            HDsnprintf(srcdir_testpath, sizeof(srcdir_testpath), "%s%s", srcdir, filename);
-            return(srcdir_testpath);
-        } /* end if */
-        else
-            return(NULL);
-    } /* end else */
-} /* end H5_get_srcdir_filename() */
-
diff --git a/test/H5srcdir.h b/test/H5srcdir.h
index d0a4bf7..32fe8c9 100644
--- a/test/H5srcdir.h
+++ b/test/H5srcdir.h
@@ -24,16 +24,47 @@
 #include "H5srcdir_str.h"
 
 /* Buffer to construct path in and return pointer to */
-extern char srcdir_path[1024];
+static char srcdir_path[1024] = "";
 
 /* Buffer to construct file in and return pointer to */
-extern char srcdir_testpath[1024];
+static char srcdir_testpath[1024] = "";
 
 /* Just return the srcdir path */
-const char *H5_get_srcdir(void);
+static const char *
+H5_get_srcdir(void)
+{
+    const char *srcdir = HDgetenv("srcdir");
+
+    /* Check for using the srcdir from configure time */
+    if(NULL == srcdir)
+        srcdir = config_srcdir;
+
+    /* Build path to all test files */
+    if((HDstrlen(srcdir) + 2) < sizeof(srcdir_path)) {
+        HDsnprintf(srcdir_path, sizeof(srcdir_path), "%s/", srcdir);
+        return(srcdir_path);
+    } /* end if */
+    else
+        return(NULL);
+} /* end H5_get_srcdir() */
 
 /* Append the test file name to the srcdir path and return the whole string */
-const char *H5_get_srcdir_filename(const char *);
+static const char *H5_get_srcdir_filename(const char *filename)
+{
+    const char *srcdir = H5_get_srcdir();
 
+    /* Check for error */
+    if(NULL == srcdir)
+        return(NULL);
+    else {
+        /* Build path to test file */
+        if((HDstrlen(srcdir) + HDstrlen(filename) + 1) < sizeof(srcdir_testpath)) {
+            HDsnprintf(srcdir_testpath, sizeof(srcdir_testpath), "%s%s", srcdir, filename);
+            return(srcdir_testpath);
+        } /* end if */
+        else
+            return(NULL);
+    } /* end else */
+} /* end H5_get_srcdir_filename() */
 #endif /* _H5SRCDIR_H */
 
diff --git a/test/H5srcdir_str.h.in b/test/H5srcdir_str.h.in
index ba30a88..bab1df3 100644
--- a/test/H5srcdir_str.h.in
+++ b/test/H5srcdir_str.h.in
@@ -16,5 +16,5 @@
  */
 
 /* Set the 'srcdir' path from configure time */
-#define config_srcdir "@srcdir@"
+static const char *config_srcdir = "@srcdir@";
 
diff --git a/test/Makefile.am b/test/Makefile.am
index d66200d..57080aa 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -135,7 +135,7 @@ else
   noinst_LTLIBRARIES=libh5test.la
 endif
 
-libh5test_la_SOURCES=h5test.c testframe.c cache_common.c swmr_common.c external_common.c H5srcdir.c
+libh5test_la_SOURCES=h5test.c testframe.c cache_common.c swmr_common.c external_common.c
 
 # Use libhd5test.la to compile all of the tests
 LDADD=libh5test.la $(LIBHDF5)
@@ -145,12 +145,6 @@ ttsafe_SOURCES=ttsafe.c ttsafe_dcreate.c ttsafe_error.c ttsafe_cancel.c       \
                ttsafe_acreate.c
 cache_image_SOURCES=cache_image.c genall5.c
 
-#filter_plugin_SOURCES=filter_plugin.c H5srcdir.c
-
-vds_swmr_gen_SOURCES=vds_swmr_gen.c vds_swmr_common.c
-vds_swmr_writer_SOURCES=vds_swmr_writer.c vds_swmr_common.c
-vds_swmr_reader_SOURCES=vds_swmr_reader.c vds_swmr_common.c
-
 VFD_LIST = sec2 stdio core core_paged split multi family
 if DIRECT_VFD_CONDITIONAL
   VFD_LIST += direct
diff --git a/test/cache.c b/test/cache.c
index e59dc3e..1a726fa 100644
--- a/test/cache.c
+++ b/test/cache.c
@@ -16926,7 +16926,7 @@ check_move_entry_errs(unsigned paged)
 {
     herr_t result;
     H5F_t * file_ptr = NULL;
-    H5C_t * cache_ptr;
+    H5C_t * cache_ptr = NULL;
     test_entry_t * entry_ptr = NULL;
     test_entry_t * entry_0_0_ptr;
     test_entry_t * entry_0_1_ptr;
diff --git a/test/cache_common.c b/test/cache_common.c
index 740523e..24962bc 100644
--- a/test/cache_common.c
+++ b/test/cache_common.c
@@ -5522,7 +5522,7 @@ col_major_scan_backward(H5F_t * file_ptr,
     int mile_stone = 1;
     int32_t type;
     int32_t idx;
-    int32_t local_max_index[NUMBER_OF_ENTRY_TYPES] = {0};
+    int32_t local_max_index[NUMBER_OF_ENTRY_TYPES];
 
     if ( verbose )
         HDfprintf(stdout, "%s: entering.\n", FUNC);
diff --git a/test/cache_tagging.c b/test/cache_tagging.c
index c3921ea..7ce4e88 100644
--- a/test/cache_tagging.c
+++ b/test/cache_tagging.c
@@ -528,7 +528,7 @@ check_file_open_tags(hid_t fcpl, int type)
     hid_t fid = -1;          /* File Identifier */
     int verbose = FALSE;     /* verbose file outout */
     hid_t fapl = -1;         /* File access prop list */
-    haddr_t root_tag = HADDR_UNDEF;       /* Root Group Tag */
+    haddr_t root_tag;       /* Root Group Tag */
     haddr_t sbe_tag;        /* Sblock Extension Tag */
 
     /* Testing Macro */
diff --git a/test/del_many_dense_attrs.c b/test/del_many_dense_attrs.c
index ce85d1b..ada7a6f 100644
--- a/test/del_many_dense_attrs.c
+++ b/test/del_many_dense_attrs.c
@@ -70,7 +70,7 @@ main(void)
     hid_t fapl = -1;            /* File access property lists   */
     hid_t gcpl = -1;            /* Group creation property list */
     char aname[50];             /* Name of attribute            */
-    const char *basename="attr";/* Name prefix for attribute    */
+    char *basename="attr";      /* Name prefix for attribute    */
     char filename[100];         /* File name                    */
     int i;                      /* Local index variable         */
 
diff --git a/test/dsets.c b/test/dsets.c
index aa84833..eaa469f 100644
--- a/test/dsets.c
+++ b/test/dsets.c
@@ -7065,15 +7065,16 @@ static void
 make_random_offset_and_increment(long nelts, long *offsetp, long *incp)
 {
     long inc;
-    /* `maxinc` is chosen so that for any `x` in [0, nelts - 1],
-     * `x + maxinc` does not overflow a long.
-     */
-    const long maxinc = MIN(nelts - 1, LONG_MAX - nelts);
 
     HDassert(0 < nelts);
 
     *offsetp = HDrandom() % nelts;
 
+    /* `maxinc` is chosen so that for any `x` in [0, nelts - 1],
+     * `x + maxinc` does not overflow a long.
+     */
+    const long maxinc = MIN(nelts - 1, LONG_MAX - nelts);
+
     /* Choose a random number in [1, nelts - 1].  If its greatest divisor
      * in common with `nelts` is 1, then it will "generate" the additive ring
      * [0, nelts - 1], so let it be our increment.  Otherwise, choose a new
diff --git a/test/dt_arith.c b/test/dt_arith.c
index 8d04770..7e1adf5 100644
--- a/test/dt_arith.c
+++ b/test/dt_arith.c
@@ -770,7 +770,7 @@ static int test_particular_fp_integer(void)
 
     /* Print errors */
     if(dst_c != SCHAR_MAX) {
-        double x = 0.;
+        double x;
         signed char   y;
 
         if(0 == fails_this_test++)
@@ -814,7 +814,7 @@ static int test_particular_fp_integer(void)
 
     /* Print errors */
     if(dst_i != fill_value) {
-        float x = 0.;
+        float x;
         int   y;
 
         if(0 == fails_this_test++)
@@ -2723,16 +2723,16 @@ my_isnan(dtype_t type, void *val)
     char s[256];
 
     if (FLT_FLOAT==type) {
-    float x = 0.;
+    float x;
     HDmemcpy(&x, val, sizeof(float));
     retval = (x!=x);
     } else if (FLT_DOUBLE==type) {
-    double x = 0.;
+    double x;
     HDmemcpy(&x, val, sizeof(double));
     retval = (x!=x);
 #if H5_SIZEOF_LONG_DOUBLE!=H5_SIZEOF_DOUBLE && H5_SIZEOF_LONG_DOUBLE!=0
     } else if (FLT_LDOUBLE==type) {
-    long double x = 0.;
+    long double x;
     HDmemcpy(&x, val, sizeof(long double));
     retval = (x!=x);
 #endif
@@ -2746,18 +2746,18 @@ my_isnan(dtype_t type, void *val)
      */
     if (!retval) {
     if (FLT_FLOAT==type) {
-        float x = 0.;
+        float x;
 
         HDmemcpy(&x, val, sizeof(float));
         HDsnprintf(s, sizeof(s), "%g", (double)x);
     } else if (FLT_DOUBLE==type) {
-        double x = 0.;
+        double x;
 
         HDmemcpy(&x, val, sizeof(double));
         HDsnprintf(s, sizeof(s), "%g", x);
 #if H5_SIZEOF_LONG_DOUBLE!=H5_SIZEOF_DOUBLE && H5_SIZEOF_LONG_DOUBLE!=0
     } else if (FLT_LDOUBLE==type) {
-        long double x = 0.;
+        long double x;
 
         HDmemcpy(&x, val, sizeof(long double));
         HDsnprintf(s, sizeof(s), "%Lg", x);
@@ -3197,7 +3197,7 @@ test_conv_flt_1 (const char *name, int run_test, hid_t src, hid_t dst)
             int        check_expo[2];
 
             if (FLT_FLOAT==dst_type) {
-                float x = 0.;
+                float x;
                 HDmemcpy(&x, &buf[j*dst_size], sizeof(float));
                 if (underflow &&
                         HDfabsf(x) <= FLT_MIN && HDfabsf(hw_f) <= FLT_MIN)
@@ -3208,7 +3208,7 @@ test_conv_flt_1 (const char *name, int run_test, hid_t src, hid_t dst)
                 check_mant[0] = HDfrexpf(x, check_expo+0);
                 check_mant[1] = HDfrexpf(hw_f, check_expo+1);
             } else if (FLT_DOUBLE==dst_type) {
-                double x = 0.;
+                double x;
                 HDmemcpy(&x, &buf[j*dst_size], sizeof(double));
                 if (underflow &&
                         HDfabs(x) <= DBL_MIN && HDfabs(hw_d) <= DBL_MIN)
@@ -3220,7 +3220,7 @@ test_conv_flt_1 (const char *name, int run_test, hid_t src, hid_t dst)
                 check_mant[1] = HDfrexp(hw_d, check_expo+1);
 #if H5_SIZEOF_LONG_DOUBLE !=0 && (H5_SIZEOF_LONG_DOUBLE!=H5_SIZEOF_DOUBLE)
             } else {
-                long double x = 0.;
+                long double x;
                 HDmemcpy(&x, &buf[j*dst_size], sizeof(long double));
                 /* dst is largest float, no need to check underflow. */
                 check_mant[0] = (double)HDfrexpl(x, check_expo+0);
@@ -3265,16 +3265,16 @@ test_conv_flt_1 (const char *name, int run_test, hid_t src, hid_t dst)
             HDprintf(" %02x", saved[j*src_size+ENDIAN(src_size,k,sendian)]);
         HDprintf("%*s", (int)(3*MAX(0, (ssize_t)dst_size-(ssize_t)src_size)), "");
         if (FLT_FLOAT==src_type) {
-            float x = 0.;
+            float x;
             HDmemcpy(&x, &saved[j*src_size], sizeof(float));
             HDprintf(" %29.20e\n", (double)x);
         } else if (FLT_DOUBLE==src_type) {
-            double x = 0.;
+            double x;
             HDmemcpy(&x, &saved[j*src_size], sizeof(double));
             HDprintf(" %29.20e\n", x);
 #if H5_SIZEOF_LONG_DOUBLE!=H5_SIZEOF_DOUBLE
         } else {
-            long double x = 0.;
+            long double x;
             HDmemcpy(&x, &saved[j*src_size], sizeof(long double));
             HDfprintf(stdout," %29.20Le\n", x);
 #endif
@@ -3285,16 +3285,16 @@ test_conv_flt_1 (const char *name, int run_test, hid_t src, hid_t dst)
             HDprintf(" %02x", buf[j*dst_size+ENDIAN(dst_size,k,dendian)]);
         HDprintf("%*s", (int)(3*MAX(0, (ssize_t)src_size-(ssize_t)dst_size)), "");
         if (FLT_FLOAT==dst_type) {
-            float x = 0.;
+            float x;
             HDmemcpy(&x, &buf[j*dst_size], sizeof(float));
             HDprintf(" %29.20e\n", (double)x);
         } else if (FLT_DOUBLE==dst_type) {
-            double x = 0.;
+            double x;
             HDmemcpy(&x, &buf[j*dst_size], sizeof(double));
             HDprintf(" %29.20e\n", x);
 #if H5_SIZEOF_LONG_DOUBLE!=H5_SIZEOF_DOUBLE
         } else {
-            long double x = 0.;
+            long double x;
             HDmemcpy(&x, &buf[j*dst_size], sizeof(long double));
             HDfprintf(stdout," %29.20Le\n", x);
 #endif
diff --git a/test/fillval.c b/test/fillval.c
index dd0ca7f..47cd53a 100644
--- a/test/fillval.c
+++ b/test/fillval.c
@@ -762,11 +762,6 @@ test_rdwr_cases(hid_t file, hid_t dcpl, const char *dname, void *_fillval,
     comp_datatype    *buf_c=NULL;
     H5D_space_status_t  allocation;
 
-    fill_c.a = 0;
-    fill_c.x = 0;
-    fill_c.y = 0;
-    fill_c.z = 0;
-
     if(datatype == H5T_INTEGER) {
         fillval = *(int*)_fillval;
     }
diff --git a/test/null_vol_connector.c b/test/null_vol_connector.c
index 64f62c4..5ed8545 100644
--- a/test/null_vol_connector.c
+++ b/test/null_vol_connector.c
@@ -116,12 +116,6 @@ static const H5VL_class_t null_vol_g = {
         NULL,                                       /* optional     */
         NULL                                        /* free         */
     },
-    {   /* blob_cls */
-        NULL,                                       /* put */
-        NULL,                                       /* get */
-        NULL,                                       /* specific */
-        NULL                                        /* optional */
-    },
     NULL                                            /* optional     */
 };
 
diff --git a/test/objcopy_ref.c b/test/objcopy_ref.c
index fdb3179..721a7c6 100644
--- a/test/objcopy_ref.c
+++ b/test/objcopy_ref.c
@@ -1587,6 +1587,7 @@ main(void)
     unsigned    max_compact, min_dense;
     int     configuration;  /* Configuration of tests. */
     int    ExpressMode;
+    hbool_t same_file;  /* Whether to run tests that only use one file */
 
     /* Setup */
     h5_reset();
@@ -1619,6 +1620,11 @@ main(void)
         hid_t fcpl_src;
         hid_t fcpl_dst;
 
+        /* Start with same_file == TRUE.  Use source file settings for these
+         * tests.  Don't run with a non-default destination file setting, as
+         * destination settings have no effect. */
+        same_file = TRUE;
+
         /* No need to test dense attributes with old format */
         if(!(configuration & CONFIG_SRC_NEW_FORMAT) && (configuration & CONFIG_DENSE))
             continue;
@@ -1640,6 +1646,7 @@ main(void)
         if(configuration & CONFIG_SHARE_DST) {
             HDputs("Testing with shared dst messages:");
             fcpl_dst = fcpl_shared;
+            same_file = FALSE;
         }
         else {
             HDputs("Testing without shared dst messages:");
@@ -1671,6 +1678,7 @@ main(void)
         if(configuration & CONFIG_DST_NEW_FORMAT) {
             HDputs("Testing with latest format for destination file:");
             dst_fapl = fapl2;
+            same_file = FALSE;
         } /* end if */
         else {
             HDputs("Testing with oldest file format for destination file:");
diff --git a/test/swmr_sparse_reader.c b/test/swmr_sparse_reader.c
index a969b16..6adc6c5 100644
--- a/test/swmr_sparse_reader.c
+++ b/test/swmr_sparse_reader.c
@@ -115,7 +115,7 @@ check_dataset(hid_t fid, unsigned verbose, const symbol_info_t *symbol, symbol_t
 
     /* Emit informational message */
     if(verbose)
-        HDfprintf(stderr, "Symbol = '%s', location = %ju,%ju\n", symbol->name, (uintmax_t)start[0], (uintmax_t)start[1]);
+        HDfprintf(stderr, "Symbol = '%s', location = %lld\n", symbol->name, (long long)start);
 
     /* Read record from dataset */
     record->rec_id = (uint64_t)ULLONG_MAX;
@@ -126,7 +126,7 @@ check_dataset(hid_t fid, unsigned verbose, const symbol_info_t *symbol, symbol_t
     if(record->rec_id != start[1]) {
         HDfprintf(stderr, "*** ERROR ***\n");
         HDfprintf(stderr, "Incorrect record value!\n");
-        HDfprintf(stderr, "Symbol = '%s', location = %ju,%ju, record->rec_id = %" PRIu64 "\n", symbol->name, (uintmax_t)start[0], (uintmax_t)start[1], record->rec_id);
+        HDfprintf(stderr, "Symbol = '%s', location = %lld, record->rec_id = %llu\n", symbol->name, (long long)start, (unsigned long long)record->rec_id);
         return -1;
     } /* end if */
 
diff --git a/test/tid.c b/test/tid.c
index 7a839d2..d0ae3e4 100644
--- a/test/tid.c
+++ b/test/tid.c
@@ -19,13 +19,6 @@
 #define H5I_FRIEND        /*suppress error about including H5Ipkg      */
 #include "H5Ipkg.h"
 
-static herr_t
-free_wrapper(void *p)
-{
-    HDfree(p);
-    return SUCCEED;
-}
-
 /* Test basic functionality of registering and deleting types and IDs */
 static int basic_id_test(void)
 {
@@ -76,7 +69,7 @@ static int basic_id_test(void)
         goto out;
 
     /* Register a type */
-    myType = H5Iregister_type((size_t)64, 0, free_wrapper);
+    myType = H5Iregister_type((size_t)64, 0, (H5I_free_t) free );
 
     CHECK(myType, H5I_BADID, "H5Iregister_type");
     if(myType == H5I_BADID)
@@ -170,7 +163,7 @@ static int basic_id_test(void)
     H5E_END_TRY
 
     /* Register another type and another object in that type */
-    myType = H5Iregister_type((size_t)64, 0, free_wrapper);
+    myType = H5Iregister_type((size_t)64, 0, (H5I_free_t) free );
 
     CHECK(myType, H5I_BADID, "H5Iregister_type");
     if(myType == H5I_BADID)
@@ -245,7 +238,7 @@ out:
 
 
     /* A dummy search function for the next test */
-static int test_search_func(void H5_ATTR_UNUSED * ptr1, hid_t H5_ATTR_UNUSED id, void H5_ATTR_UNUSED * ptr2) { return 0; }
+static int test_search_func(void H5_ATTR_UNUSED * ptr1, void H5_ATTR_UNUSED * ptr2) { return 0; }
 
     /* Ensure that public functions cannot access "predefined" ID types */
 static int id_predefined_test(void )
@@ -271,7 +264,7 @@ static int id_predefined_test(void )
         goto out;
 
     H5E_BEGIN_TRY
-        testPtr = H5Isearch(H5I_GENPROP_LST, test_search_func, testObj);
+        testPtr = H5Isearch(H5I_GENPROP_LST, (H5I_search_func_t) test_search_func, testObj);
     H5E_END_TRY
 
     CHECK_PTR_NULL(testPtr, "H5Isearch");
@@ -499,7 +492,7 @@ static int test_id_type_list(void)
     H5I_type_t testType;
     int i;    /* Just a counter variable */
 
-    startType = H5Iregister_type((size_t)8, 0, free_wrapper);
+    startType = H5Iregister_type((size_t)8, 0, (H5I_free_t) free );
     CHECK(startType, H5I_BADID, "H5Iregister_type");
     if(startType == H5I_BADID)
         goto out;
@@ -514,7 +507,7 @@ static int test_id_type_list(void)
     /* Create types up to H5I_MAX_NUM_TYPES */
     for(i = startType + 1; i < H5I_MAX_NUM_TYPES; i++)
     {
-        currentType = H5Iregister_type((size_t)8, 0, free_wrapper);
+        currentType = H5Iregister_type((size_t)8, 0, (H5I_free_t) free );
         CHECK(currentType, H5I_BADID, "H5Iregister_type");
         if(currentType == H5I_BADID)
             goto out;
@@ -523,7 +516,7 @@ static int test_id_type_list(void)
     /* Wrap around to low type ID numbers */
     for(i = H5I_NTYPES; i < startType; i++)
     {
-        currentType = H5Iregister_type((size_t)8, 0, free_wrapper);
+        currentType = H5Iregister_type((size_t)8, 0, (H5I_free_t) free );
         CHECK(currentType, H5I_BADID, "H5Iregister_type");
         if(currentType == H5I_BADID)
             goto out;
@@ -531,7 +524,7 @@ static int test_id_type_list(void)
 
     /* There should be no room at the inn for a new ID type*/
     H5E_BEGIN_TRY
-        testType = H5Iregister_type((size_t)8, 0, free_wrapper);
+        testType = H5Iregister_type((size_t)8, 0, (H5I_free_t) free );
     H5E_END_TRY
 
     VERIFY(testType, H5I_BADID, "H5Iregister_type");
@@ -540,7 +533,7 @@ static int test_id_type_list(void)
 
     /* Now delete a type and try to insert again */
     H5Idestroy_type(H5I_NTYPES);
-    testType = H5Iregister_type((size_t)8, 0, free_wrapper);
+    testType = H5Iregister_type((size_t)8, 0, (H5I_free_t) free );
 
     VERIFY(testType, H5I_NTYPES, "H5Iregister_type");
     if(testType != H5I_NTYPES)
diff --git a/test/trefer.c b/test/trefer.c
index 4ffc2dc..0f9e4f9 100644
--- a/test/trefer.c
+++ b/test/trefer.c
@@ -89,9 +89,9 @@ test_reference_params(void)
     H5R_ref_t     *wbuf,       /* buffer to write to disk          */
                *rbuf,       /* buffer read from disk            */
                *tbuf;       /* temp. buffer read from disk      */
-    unsigned *obuf;
     H5R_type_t  type;       /* Reference type                   */
-    unsigned int i;          /* Counters                         */
+    unsigned   *tu32;       /* Temporary pointer to uint32 data */
+    int         i;          /* Counters                         */
     const char *write_comment = "Foo!"; /* Comments for group   */
     hid_t       ret_id;     /* Generic hid_t return value       */
     ssize_t     name_size;  /* Size of reference name           */
@@ -101,13 +101,12 @@ test_reference_params(void)
     MESSAGE(5, ("Testing Reference Parameters\n"));
 
     /* Allocate write & read buffers */
-    wbuf = (H5R_ref_t *)HDcalloc(sizeof(H5R_ref_t), SPACE1_DIM1);
-    rbuf = (H5R_ref_t *)HDcalloc(sizeof(H5R_ref_t), SPACE1_DIM1);
-    tbuf = (H5R_ref_t *)HDcalloc(sizeof(H5R_ref_t), SPACE1_DIM1);
-    obuf = HDcalloc(sizeof(unsigned), SPACE1_DIM1);
+    wbuf = (H5R_ref_t *)HDcalloc(MAX(sizeof(unsigned), sizeof(H5R_ref_t)), SPACE1_DIM1);
+    rbuf = (H5R_ref_t *)HDcalloc(MAX(sizeof(unsigned), sizeof(H5R_ref_t)), SPACE1_DIM1);
+    tbuf = (H5R_ref_t *)HDcalloc(MAX(sizeof(unsigned), sizeof(H5R_ref_t)), SPACE1_DIM1);
 
-    for(i = 0; i < SPACE1_DIM1; i++)
-        obuf[i] = i * 3;
+    for(tu32 = (unsigned *)wbuf, i = 0; i < SPACE1_DIM1; i++)
+        *tu32++ = (unsigned)i * 3;
 
     /* Create file */
     fid1 = H5Fcreate(FILE_REF_PARAM, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
@@ -138,7 +137,7 @@ test_reference_params(void)
     CHECK(dataset, H5I_INVALID_HID, "H5Dcreate2");
 
     /* Write selection to disk */
-    ret = H5Dwrite(dataset, H5T_NATIVE_UINT, H5S_ALL, H5S_ALL, H5P_DEFAULT, obuf);
+    ret = H5Dwrite(dataset, H5T_NATIVE_UINT, H5S_ALL, H5S_ALL, H5P_DEFAULT, wbuf);
     CHECK(ret, FAIL, "H5Dwrite");
 
     /* Close Dataset */
@@ -154,7 +153,7 @@ test_reference_params(void)
     CHECK(attr, H5I_INVALID_HID, "H5Acreate2");
 
     /* Write attribute to disk */
-    ret = H5Awrite(attr, H5T_NATIVE_UINT, obuf);
+    ret = H5Awrite(attr, H5T_NATIVE_UINT, wbuf);
     CHECK(ret, FAIL, "H5Awrite");
 
     /* Close attribute */
@@ -234,19 +233,19 @@ test_reference_params(void)
     VERIFY(type, H5R_BADTYPE, "H5Rget_type ref");
 
     /* Test parameters to H5Requal */
-    ret = H5Requal(NULL, &rbuf[0]);
+    ret = H5Requal(NULL, (const H5R_ref_t *)&rbuf[0]);
     VERIFY(ret, FAIL, "H5Requal ref1");
-    ret = H5Requal(&rbuf[0], NULL);
+    ret = H5Requal((const H5R_ref_t *)&rbuf[0], NULL);
     VERIFY(ret, FAIL, "H5Requal ref2");
 
     /* Test parameters to H5Rcopy */
     ret = H5Rcopy(NULL, &wbuf[0]);
     VERIFY(ret, FAIL, "H5Rcopy src_ref");
-    ret = H5Rcopy(&rbuf[0], NULL);
+    ret = H5Rcopy((const H5R_ref_t *)&rbuf[0], NULL);
     VERIFY(ret, FAIL, "H5Rcopy dest_ref");
 
     /* Test parameters to H5Ropen_object */
-    dset2 = H5Ropen_object(&rbuf[0], H5I_INVALID_HID, H5I_INVALID_HID);
+    dset2 = H5Ropen_object((const H5R_ref_t *)&rbuf[0], H5I_INVALID_HID, H5I_INVALID_HID);
     VERIFY(dset2, FAIL, "H5Ropen_object oapl_id");
     dset2 = H5Ropen_object(NULL, H5P_DEFAULT, dapl_id);
     VERIFY(dset2, FAIL, "H5Ropen_object ref");
@@ -299,7 +298,6 @@ test_reference_params(void)
     HDfree(wbuf);
     HDfree(rbuf);
     HDfree(tbuf);
-    HDfree(obuf);
 }   /* test_reference_params() */
 
 /****************************************************************
@@ -320,9 +318,10 @@ test_reference_obj(void)
     hsize_t     dims1[] = {SPACE1_DIM1};
     hid_t       dapl_id;    /* Dataset access property list     */
     H5R_ref_t     *wbuf,       /* buffer to write to disk          */
-               *rbuf;       /* buffer read from disk            */
-    unsigned    *ibuf, *obuf;
-    unsigned         i, j;       /* Counters                         */
+               *rbuf,       /* buffer read from disk            */
+               *tbuf;       /* temp. buffer read from disk      */
+    unsigned   *tu32;       /* Temporary pointer to uint32 data */
+    int         i, j;       /* Counters                         */
     H5O_type_t  obj_type;   /* Object type                      */
     herr_t      ret;        /* Generic return value             */
 
@@ -330,13 +329,12 @@ test_reference_obj(void)
     MESSAGE(5, ("Testing Object Reference Functions\n"));
 
     /* Allocate write & read buffers */
-    wbuf = HDcalloc(sizeof(H5R_ref_t), SPACE1_DIM1);
-    rbuf = HDcalloc(sizeof(H5R_ref_t), SPACE1_DIM1);
-    ibuf = HDcalloc(sizeof(unsigned), SPACE1_DIM1);
-    obuf = HDcalloc(sizeof(unsigned), SPACE1_DIM1);
+    wbuf = (H5R_ref_t *)HDcalloc(MAX(sizeof(unsigned), sizeof(H5R_ref_t)), SPACE1_DIM1);
+    rbuf = (H5R_ref_t *)HDcalloc(MAX(sizeof(unsigned), sizeof(H5R_ref_t)), SPACE1_DIM1);
+    tbuf = (H5R_ref_t *)HDcalloc(MAX(sizeof(unsigned), sizeof(H5R_ref_t)), SPACE1_DIM1);
 
-    for (i = 0; i < SPACE1_DIM1; i++)
-        obuf[i] = i * 3;
+    for(tu32 = (unsigned *)wbuf, i = 0; i < SPACE1_DIM1; i++)
+        *tu32++ = (unsigned)i * 3;
 
     /* Create file */
     fid1 = H5Fcreate(FILE_REF_OBJ, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
@@ -359,7 +357,7 @@ test_reference_obj(void)
     CHECK(dataset, H5I_INVALID_HID, "H5Dcreate2");
 
     /* Write selection to disk */
-    ret = H5Dwrite(dataset, H5T_NATIVE_UINT, H5S_ALL, H5S_ALL, H5P_DEFAULT, obuf);
+    ret = H5Dwrite(dataset, H5T_NATIVE_UINT, H5S_ALL, H5S_ALL, H5P_DEFAULT, wbuf);
     CHECK(ret, FAIL, "H5Dwrite");
 
     /* Close Dataset */
@@ -407,28 +405,28 @@ test_reference_obj(void)
     /* Create reference to dataset */
     ret = H5Rcreate_object(fid1, "/Group1/Dataset1", &wbuf[0]);
     CHECK(ret, FAIL, "H5Rcreate_object");
-    ret = H5Rget_obj_type3(&wbuf[0], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3((const H5R_ref_t *)&wbuf[0], H5P_DEFAULT, &obj_type);
     CHECK(ret, FAIL, "H5Rget_obj_type3");
     VERIFY(obj_type, H5O_TYPE_DATASET, "H5Rget_obj_type3");
 
     /* Create reference to dataset */
     ret = H5Rcreate_object(fid1, "/Group1/Dataset2", &wbuf[1]);
     CHECK(ret, FAIL, "H5Rcreate_object");
-    ret = H5Rget_obj_type3(&wbuf[1], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3((const H5R_ref_t *)&wbuf[1], H5P_DEFAULT, &obj_type);
     CHECK(ret, FAIL, "H5Rget_obj_type3");
     VERIFY(obj_type, H5O_TYPE_DATASET, "H5Rget_obj_type3");
 
     /* Create reference to group */
     ret = H5Rcreate_object(fid1, "/Group1", &wbuf[2]);
     CHECK(ret, FAIL, "H5Rcreate_object");
-    ret = H5Rget_obj_type3(&wbuf[2], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3((const H5R_ref_t *)&wbuf[2], H5P_DEFAULT, &obj_type);
     CHECK(ret, FAIL, "H5Rget_obj_type3");
     VERIFY(obj_type, H5O_TYPE_GROUP, "H5Rget_obj_type3");
 
     /* Create reference to named datatype */
     ret = H5Rcreate_object(fid1, "/Group1/Datatype1", &wbuf[3]);
     CHECK(ret, FAIL, "H5Rcreate_object");
-    ret = H5Rget_obj_type3(&wbuf[3], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3((const H5R_ref_t *)&wbuf[3], H5P_DEFAULT, &obj_type);
     CHECK(ret, FAIL, "H5Rget_obj_type3");
     VERIFY(obj_type, H5O_TYPE_NAMED_DATATYPE, "H5Rget_obj_type3");
 
@@ -461,7 +459,7 @@ test_reference_obj(void)
     CHECK(ret, FAIL, "H5Dread");
 
     /* Open dataset object */
-    dset2 = H5Ropen_object(&rbuf[0], H5P_DEFAULT, dapl_id);
+    dset2 = H5Ropen_object((const H5R_ref_t *)&rbuf[0], H5P_DEFAULT, dapl_id);
     CHECK(dset2, H5I_INVALID_HID, "H5Ropen_object");
 
     /* Check information in referenced dataset */
@@ -472,18 +470,18 @@ test_reference_obj(void)
     VERIFY(ret, SPACE1_DIM1, "H5Sget_simple_extent_npoints");
 
     /* Read from disk */
-    ret = H5Dread(dset2, H5T_NATIVE_UINT, H5S_ALL, H5S_ALL, H5P_DEFAULT, ibuf);
+    ret = H5Dread(dset2, H5T_NATIVE_UINT, H5S_ALL, H5S_ALL, H5P_DEFAULT, tbuf);
     CHECK(ret, FAIL, "H5Dread");
 
-    for(i = 0; i < SPACE1_DIM1; i++)
-        VERIFY(ibuf[i], i * 3, "Data");
+    for(tu32 = (unsigned *)tbuf, i = 0; i < SPACE1_DIM1; i++, tu32++)
+        VERIFY(*tu32, (uint32_t)(i*3), "Data");
 
     /* Close dereferenced Dataset */
     ret = H5Dclose(dset2);
     CHECK(ret, FAIL, "H5Dclose");
 
     /* Open group object.  GAPL isn't supported yet.  But it's harmless to pass in */
-    group = H5Ropen_object(&rbuf[2], H5P_DEFAULT, H5P_DEFAULT);
+    group = H5Ropen_object((const H5R_ref_t *)&rbuf[2], H5P_DEFAULT, H5P_DEFAULT);
     CHECK(group, H5I_INVALID_HID, "H5Ropen_object");
 
     /* Close group */
@@ -491,7 +489,7 @@ test_reference_obj(void)
     CHECK(ret, FAIL, "H5Gclose");
 
     /* Open datatype object. TAPL isn't supported yet.  But it's harmless to pass in */
-    tid1 = H5Ropen_object(&rbuf[3], H5P_DEFAULT, H5P_DEFAULT);
+    tid1 = H5Ropen_object((const H5R_ref_t *)&rbuf[3], H5P_DEFAULT, H5P_DEFAULT);
     CHECK(tid1, H5I_INVALID_HID, "H5Ropen_object");
 
     /* Verify correct datatype */
@@ -532,8 +530,7 @@ test_reference_obj(void)
     /* Free memory buffers */
     HDfree(wbuf);
     HDfree(rbuf);
-    HDfree(ibuf);
-    HDfree(obuf);
+    HDfree(tbuf);
 }   /* test_reference_obj() */
 
 /****************************************************************
@@ -568,7 +565,7 @@ test_reference_region(H5F_libver_t libver_low, H5F_libver_t libver_high)
     hsize_t high[SPACE2_RANK];      /* Selection bounds */
     H5R_ref_t *wbuf,                   /* buffer to write to disk */
            *rbuf;                   /* buffer read from disk */
-    H5R_ref_t  nvrbuf[3]={{{0}},{{101}},{{255}}}; /* buffer with non-valid refs */
+    H5R_ref_t  nvrbuf[3]={{0},{101},{255}}; /* buffer with non-valid refs */
     uint8_t *dwbuf,                 /* Buffer for writing numeric data to disk */
             *drbuf;                 /* Buffer for reading numeric data from disk */
     uint8_t *tu8;                   /* Temporary pointer to uint8 data */
@@ -586,8 +583,8 @@ test_reference_region(H5F_libver_t libver_low, H5F_libver_t libver_high)
     MESSAGE(5, ("Testing Dataset Region Reference Functions\n"));
 
     /* Allocate write & read buffers */
-    wbuf = HDcalloc(sizeof(H5R_ref_t), SPACE1_DIM1);
-    rbuf = HDcalloc(sizeof(H5R_ref_t), SPACE1_DIM1);
+    wbuf = (H5R_ref_t *)HDcalloc(sizeof(H5R_ref_t), SPACE1_DIM1);
+    rbuf = (H5R_ref_t *)HDcalloc(sizeof(H5R_ref_t), SPACE1_DIM1);
     dwbuf = (uint8_t *)HDcalloc(sizeof(uint8_t), (size_t)(SPACE2_DIM1 * SPACE2_DIM2));
     drbuf = (uint8_t *)HDcalloc(sizeof(uint8_t), (size_t)(SPACE2_DIM1 * SPACE2_DIM2));
 
@@ -650,7 +647,7 @@ test_reference_region(H5F_libver_t libver_low, H5F_libver_t libver_high)
     /* Store first dataset region */
     ret = H5Rcreate_region(fid1, "/Dataset2", sid2, &wbuf[0]);
     CHECK(ret, FAIL, "H5Rcreate_region");
-    ret = H5Rget_obj_type3(&wbuf[0], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3((const H5R_ref_t *)&wbuf[0], H5P_DEFAULT, &obj_type);
     CHECK(ret, FAIL, "H5Rget_obj_type3");
     VERIFY(obj_type, H5O_TYPE_DATASET, "H5Rget_obj_type3");
 
@@ -694,7 +691,7 @@ test_reference_region(H5F_libver_t libver_low, H5F_libver_t libver_high)
     ret = H5Rcreate_region(fid1, "/Dataset2", sid2, &wbuf[2]);
     CHECK(ret, FAIL, "H5Rcreate_region");
 
-    ret = H5Rget_obj_type3(&wbuf[2], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3((const H5R_ref_t *)&wbuf[2], H5P_DEFAULT, &obj_type);
     CHECK(ret, FAIL, "H5Rget_obj_type3");
     VERIFY(obj_type, H5O_TYPE_DATASET, "H5Rget_obj_type3");
 
@@ -767,7 +764,7 @@ test_reference_region(H5F_libver_t libver_low, H5F_libver_t libver_high)
      * Dereference an undefined reference (should fail)
      */
     H5E_BEGIN_TRY {
-      dset2 = H5Ropen_object(&rdata_NA[0], H5P_DEFAULT, H5P_DEFAULT);
+      dset2 = H5Ropen_object((const H5R_ref_t *)&rdata_NA[0], H5P_DEFAULT, H5P_DEFAULT);
     } H5E_END_TRY;
     VERIFY(dset2, H5I_INVALID_HID, "H5Ropen_object");
 
@@ -796,16 +793,16 @@ test_reference_region(H5F_libver_t libver_low, H5F_libver_t libver_high)
     } H5E_END_TRY;
 
     if(libver_high < H5F_LIBVER_V110)
-        VERIFY(ret, FAIL, "H5Dread");
+        CHECK(ret, FAIL, "H5Dread");
     else {
         CHECK(ret, FAIL, "H5Dread");
 
         /* Try to open objects */
-        dset2 = H5Ropen_object(&rbuf[0], H5P_DEFAULT, dapl_id);
+        dset2 = H5Ropen_object((const H5R_ref_t *)&rbuf[0], H5P_DEFAULT, dapl_id);
         CHECK(dset2, H5I_INVALID_HID, "H5Ropen_object");
 
         /* Check what H5Rget_obj_type3 function returns */
-        ret = H5Rget_obj_type3(&rbuf[0], H5P_DEFAULT, &obj_type);
+        ret = H5Rget_obj_type3((const H5R_ref_t *)&rbuf[0], H5P_DEFAULT, &obj_type);
         CHECK(ret, FAIL, "H5Rget_obj_type3");
         VERIFY(obj_type, H5O_TYPE_DATASET, "H5Rget_obj_type3");
 
@@ -824,7 +821,7 @@ test_reference_region(H5F_libver_t libver_low, H5F_libver_t libver_high)
             VERIFY(*tu8, (uint8_t)(i * 3), "Data");
 
         /* Get the hyperslab selection */
-        sid2 = H5Ropen_region(&rbuf[0], H5P_DEFAULT, H5P_DEFAULT);
+        sid2 = H5Ropen_region((const H5R_ref_t *)&rbuf[0], H5P_DEFAULT, H5P_DEFAULT);
         CHECK(sid2, H5I_INVALID_HID, "H5Ropen_region");
 
         /* Verify correct hyperslab selected */
@@ -852,7 +849,7 @@ test_reference_region(H5F_libver_t libver_low, H5F_libver_t libver_high)
         CHECK(ret, FAIL, "H5Sclose");
 
         /* Get the element selection */
-        sid2 = H5Ropen_region(&rbuf[1], H5P_DEFAULT, H5P_DEFAULT);
+        sid2 = H5Ropen_region((const H5R_ref_t *)&rbuf[1], H5P_DEFAULT, H5P_DEFAULT);
         CHECK(sid2, H5I_INVALID_HID, "H5Ropen_region");
 
         /* Verify correct elements selected */
@@ -896,7 +893,7 @@ test_reference_region(H5F_libver_t libver_low, H5F_libver_t libver_high)
         CHECK(ret, FAIL, "H5Sclose");
 
         /* Get the unlimited selection */
-        sid2 = H5Ropen_region(&rbuf[2], H5P_DEFAULT, H5P_DEFAULT);
+        sid2 = H5Ropen_region((const H5R_ref_t *)&rbuf[2], H5P_DEFAULT, H5P_DEFAULT);
         CHECK(sid2, H5I_INVALID_HID, "H5Ropen_region");
 
         /* Verify correct hyperslab selected */
@@ -931,7 +928,7 @@ test_reference_region(H5F_libver_t libver_low, H5F_libver_t libver_high)
         /* Attempting to retrieve type of object using non-valid refs */
         for(j = 0; j < 3; j++) {
             H5E_BEGIN_TRY {
-                ret = H5Rget_obj_type3(&nvrbuf[j], H5P_DEFAULT, &obj_type);
+                ret = H5Rget_obj_type3((const H5R_ref_t *)&nvrbuf[j], H5P_DEFAULT, &obj_type);
             } H5E_END_TRY;
             VERIFY(ret, FAIL, "H5Rget_obj_type3");
         } /* end for */
@@ -1009,8 +1006,8 @@ test_reference_region_1D(H5F_libver_t libver_low, H5F_libver_t libver_high)
     MESSAGE(5, ("Testing 1-D Dataset Region Reference Functions\n"));
 
     /* Allocate write & read buffers */
-    wbuf = HDcalloc(sizeof(H5R_ref_t), (size_t)SPACE1_DIM1);
-    rbuf = HDcalloc(sizeof(H5R_ref_t), (size_t)SPACE1_DIM1);
+    wbuf = (H5R_ref_t *)HDcalloc(sizeof(H5R_ref_t), (size_t)SPACE1_DIM1);
+    rbuf = (H5R_ref_t *)HDcalloc(sizeof(H5R_ref_t), (size_t)SPACE1_DIM1);
     dwbuf = (uint8_t *)HDcalloc(sizeof(uint8_t), (size_t)SPACE3_DIM1);
     drbuf = (uint8_t *)HDcalloc(sizeof(uint8_t), (size_t)SPACE3_DIM1);
 
@@ -1073,7 +1070,7 @@ test_reference_region_1D(H5F_libver_t libver_low, H5F_libver_t libver_high)
     /* Store first dataset region */
     ret = H5Rcreate_region(fid1, "/Dataset2", sid3, &wbuf[0]);
     CHECK(ret, FAIL, "H5Rcreate_region");
-    ret = H5Rget_obj_type3(&wbuf[0], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3((const H5R_ref_t *)&wbuf[0], H5P_DEFAULT, &obj_type);
     CHECK(ret, FAIL, "H5Rget_obj_type3");
     VERIFY(obj_type, H5O_TYPE_DATASET, "H5Rget_obj_type3");
 
@@ -1131,11 +1128,11 @@ test_reference_region_1D(H5F_libver_t libver_low, H5F_libver_t libver_high)
     CHECK(ret, FAIL, "H5Dread");
 
     /* Try to open objects */
-    dset3 = H5Ropen_object(&rbuf[0], H5P_DEFAULT, dapl_id);
+    dset3 = H5Ropen_object((const H5R_ref_t *)&rbuf[0], H5P_DEFAULT, dapl_id);
     CHECK(dset3, H5I_INVALID_HID, "H5Ropen_object");
 
     /* Check what H5Rget_obj_type3 function returns */
-    ret = H5Rget_obj_type3(&rbuf[0], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3((const H5R_ref_t *)&rbuf[0], H5P_DEFAULT, &obj_type);
     CHECK(ret, FAIL, "H5Rget_obj_type3");
     VERIFY(obj_type, H5O_TYPE_DATASET, "H5Rget_obj_type3");
 
@@ -1154,7 +1151,7 @@ test_reference_region_1D(H5F_libver_t libver_low, H5F_libver_t libver_high)
         VERIFY(*tu8, (uint8_t)(i * 3), "Data");
 
     /* Get the hyperslab selection */
-    sid3 = H5Ropen_region(&rbuf[0], H5P_DEFAULT, H5P_DEFAULT);
+    sid3 = H5Ropen_region((const H5R_ref_t *)&rbuf[0], H5P_DEFAULT, H5P_DEFAULT);
     CHECK(sid3, H5I_INVALID_HID, "H5Ropen_region");
 
     /* Verify correct hyperslab selected */
@@ -1206,7 +1203,7 @@ test_reference_region_1D(H5F_libver_t libver_low, H5F_libver_t libver_high)
     CHECK(ret, FAIL, "H5Sclose");
 
     /* Get the element selection */
-    sid3 = H5Ropen_region(&rbuf[1], H5P_DEFAULT, H5P_DEFAULT);
+    sid3 = H5Ropen_region((const H5R_ref_t *)&rbuf[1], H5P_DEFAULT, H5P_DEFAULT);
     CHECK(sid3, H5I_INVALID_HID, "H5Ropen_region");
 
     /* Verify correct elements selected */
@@ -1316,7 +1313,7 @@ test_reference_obj_deleted(void)
     /* Create reference to dataset */
     ret = H5Rcreate_object(fid1, "/Dataset1", &oref);
     CHECK(ret, FAIL, "H5Rcreate_object");
-    ret = H5Rget_obj_type3(&oref, H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3((const H5R_ref_t *)&oref, H5P_DEFAULT, &obj_type);
     CHECK(ret, FAIL, "H5Rget_obj_type3");
     VERIFY(obj_type, H5O_TYPE_DATASET, "H5Rget_obj_type3");
 
@@ -1357,7 +1354,7 @@ test_reference_obj_deleted(void)
     CHECK(ret, FAIL, "H5Dread");
 
     /* Open deleted dataset object */
-    dset2 = H5Ropen_object(&oref, H5P_DEFAULT, H5P_DEFAULT);
+    dset2 = H5Ropen_object((const H5R_ref_t *)&oref, H5P_DEFAULT, H5P_DEFAULT);
     VERIFY(dset2, H5I_INVALID_HID, "H5Ropen_object");
 
     /* Close Dataset */
@@ -1504,7 +1501,7 @@ test_reference_group(void)
     CHECK(ret, FAIL, "H5Dread");
 
     /* Dereference to get the group */
-    gid = H5Ropen_object(&rref, H5P_DEFAULT, H5P_DEFAULT);
+    gid = H5Ropen_object((const H5R_ref_t *)&rref, H5P_DEFAULT, H5P_DEFAULT);
     CHECK(gid, H5I_INVALID_HID, "H5Ropen_object");
 
     /* Iterate through objects in dereferenced group */
@@ -1565,7 +1562,8 @@ test_reference_attr(void)
     H5R_ref_t      ref_wbuf[SPACE1_DIM1], /* Buffer to write to disk */
                 ref_rbuf[SPACE1_DIM1]; /* Buffer read from disk */
     unsigned    wbuf[SPACE1_DIM1], rbuf[SPACE1_DIM1];
-    unsigned    i;          /* Local index variables */
+    unsigned    *tu32;      /* Temporary pointer to uint32 data */
+    int         i;          /* Local index variables */
     H5O_type_t  obj_type;   /* Object type */
     herr_t      ret;        /* Generic return value */
 
@@ -1592,8 +1590,8 @@ test_reference_attr(void)
     attr = H5Acreate2(group, "Attr2", H5T_NATIVE_UINT, sid, H5P_DEFAULT, H5P_DEFAULT);
     CHECK(attr, H5I_INVALID_HID, "H5Acreate2");
 
-    for(i = 0; i < SPACE1_DIM1; i++)
-        wbuf[i] = (i * 3) + 1;
+    for(tu32 = (unsigned *)wbuf, i = 0; i < SPACE1_DIM1; i++)
+        *tu32++ = (unsigned)((i * 3) + 1);
 
     /* Write attribute to disk */
     ret = H5Awrite(attr, H5T_NATIVE_UINT, wbuf);
@@ -1611,8 +1609,8 @@ test_reference_attr(void)
     attr = H5Acreate2(dataset, "Attr1", H5T_NATIVE_UINT, sid, H5P_DEFAULT, H5P_DEFAULT);
     CHECK(attr, H5I_INVALID_HID, "H5Acreate2");
 
-    for(i = 0; i < SPACE1_DIM1; i++)
-        wbuf[i] = i * 3;
+    for(tu32 = (unsigned *)wbuf, i = 0; i < SPACE1_DIM1; i++)
+        *tu32++ = (unsigned)(i * 3);
 
     /* Write attribute to disk */
     ret = H5Awrite(attr, H5T_NATIVE_UINT, wbuf);
@@ -1656,8 +1654,8 @@ test_reference_attr(void)
     attr = H5Acreate2(tid, "Attr3", H5T_NATIVE_UINT, sid, H5P_DEFAULT, H5P_DEFAULT);
     CHECK(attr, H5I_INVALID_HID, "H5Acreate2");
 
-    for(i = 0; i < SPACE1_DIM1; i++)
-        wbuf[i] = (i * 3) + 2;
+    for(tu32 = (unsigned *)wbuf, i = 0; i < SPACE1_DIM1; i++)
+        *tu32++ = (unsigned)((i * 3) + 2);
 
     /* Write attribute to disk */
     ret = H5Awrite(attr, H5T_NATIVE_UINT, wbuf);
@@ -1682,28 +1680,28 @@ test_reference_attr(void)
     /* Create reference to dataset1 attribute */
     ret = H5Rcreate_attr(fid, "/Group1/Dataset1", "Attr1", &ref_wbuf[0]);
     CHECK(ret, FAIL, "H5Rcreate_attr");
-    ret = H5Rget_obj_type3(&ref_wbuf[0], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3((const H5R_ref_t *)&ref_wbuf[0], H5P_DEFAULT, &obj_type);
     CHECK(ret, FAIL, "H5Rget_obj_type3");
     VERIFY(obj_type, H5O_TYPE_DATASET, "H5Rget_obj_type3");
 
     /* Create reference to dataset2 attribute */
     ret = H5Rcreate_attr(fid, "/Group1/Dataset2", "Attr1", &ref_wbuf[1]);
     CHECK(ret, FAIL, "H5Rcreate_attr");
-    ret = H5Rget_obj_type3(&ref_wbuf[1], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3((const H5R_ref_t *)&ref_wbuf[1], H5P_DEFAULT, &obj_type);
     CHECK(ret, FAIL, "H5Rget_obj_type3");
     VERIFY(obj_type, H5O_TYPE_DATASET, "H5Rget_obj_type3");
 
     /* Create reference to group attribute */
     ret = H5Rcreate_attr(fid, "/Group1", "Attr2", &ref_wbuf[2]);
     CHECK(ret, FAIL, "H5Rcreate_attr");
-    ret = H5Rget_obj_type3(&ref_wbuf[2], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3((const H5R_ref_t *)&ref_wbuf[2], H5P_DEFAULT, &obj_type);
     CHECK(ret, FAIL, "H5Rget_obj_type3");
     VERIFY(obj_type, H5O_TYPE_GROUP, "H5Rget_obj_type3");
 
     /* Create reference to named datatype attribute */
     ret = H5Rcreate_attr(fid, "/Group1/Datatype1", "Attr3", &ref_wbuf[3]);
     CHECK(ret, FAIL, "H5Rcreate_attr");
-    ret = H5Rget_obj_type3(&ref_wbuf[3], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3((const H5R_ref_t *)&ref_wbuf[3], H5P_DEFAULT, &obj_type);
     CHECK(ret, FAIL, "H5Rget_obj_type3");
     VERIFY(obj_type, H5O_TYPE_NAMED_DATATYPE, "H5Rget_obj_type3");
 
@@ -1736,7 +1734,7 @@ test_reference_attr(void)
     CHECK(ret, FAIL, "H5Dread");
 
     /* Open attribute on dataset object */
-    attr = H5Ropen_attr(&ref_rbuf[0], H5P_DEFAULT, H5P_DEFAULT);
+    attr = H5Ropen_attr((const H5R_ref_t *)&ref_rbuf[0], H5P_DEFAULT, H5P_DEFAULT);
     CHECK(attr, H5I_INVALID_HID, "H5Ropen_attr");
 
     /* Check information in referenced dataset */
@@ -1750,38 +1748,38 @@ test_reference_attr(void)
     ret = H5Aread(attr, H5T_NATIVE_UINT, rbuf);
     CHECK(ret, FAIL, "H5Aread");
 
-    for(i = 0; i < SPACE1_DIM1; i++)
-        VERIFY(rbuf[i], i * 3, "Data");
+    for(tu32 = (unsigned *)rbuf, i = 0; i < SPACE1_DIM1; i++, tu32++)
+        VERIFY(*tu32, (uint32_t)(i * 3), "Data");
 
     /* Close dereferenced Dataset */
     ret = H5Aclose(attr);
     CHECK(ret, FAIL, "H5Aclose");
 
     /* Open attribute on group object */
-    attr = H5Ropen_attr(&ref_rbuf[2], H5P_DEFAULT, H5P_DEFAULT);
+    attr = H5Ropen_attr((const H5R_ref_t *)&ref_rbuf[2], H5P_DEFAULT, H5P_DEFAULT);
     CHECK(attr, H5I_INVALID_HID, "H5Ropen_attr");
 
     /* Read from disk */
     ret = H5Aread(attr, H5T_NATIVE_UINT, rbuf);
     CHECK(ret, FAIL, "H5Aread");
 
-    for(i = 0; i < SPACE1_DIM1; i++)
-        VERIFY(rbuf[i], (i * 3) + 1, "Data");
+    for(tu32 = (unsigned *)rbuf, i = 0; i < SPACE1_DIM1; i++, tu32++)
+        VERIFY(*tu32, (uint32_t)((i * 3) + 1), "Data");
 
     /* Close attribute  */
     ret = H5Aclose(attr);
     CHECK(ret, FAIL, "H5Aclose");
 
     /* Open attribute on named datatype object */
-    attr = H5Ropen_attr(&ref_rbuf[3], H5P_DEFAULT, H5P_DEFAULT);
+    attr = H5Ropen_attr((const H5R_ref_t *)&ref_rbuf[3], H5P_DEFAULT, H5P_DEFAULT);
     CHECK(attr, H5I_INVALID_HID, "H5Ropen_attr");
 
     /* Read from disk */
     ret = H5Aread(attr, H5T_NATIVE_UINT, rbuf);
     CHECK(ret, FAIL, "H5Aread");
 
-    for(i = 0; i < SPACE1_DIM1; i++)
-        VERIFY(rbuf[i], (i * 3) + 2, "Data");
+    for(tu32 = (unsigned *)rbuf, i = 0; i < SPACE1_DIM1; i++, tu32++)
+        VERIFY(*tu32, (uint32_t)((i * 3) + 2), "Data");
 
     /* Close attribute  */
     ret = H5Aclose(attr);
@@ -1828,7 +1826,8 @@ test_reference_external(void)
     H5R_ref_t      ref_wbuf[SPACE1_DIM1], /* Buffer to write to disk */
                 ref_rbuf[SPACE1_DIM1]; /* Buffer read from disk */
     unsigned    wbuf[SPACE1_DIM1], rbuf[SPACE1_DIM1];
-    unsigned    i;          /* Local index variables */
+    unsigned    *tu32;      /* Temporary pointer to uint32 data */
+    int         i;          /* Local index variables */
     H5O_type_t  obj_type;   /* Object type */
     herr_t      ret;        /* Generic return value */
 
@@ -1855,8 +1854,8 @@ test_reference_external(void)
     attr = H5Acreate2(group, "Attr2", H5T_NATIVE_UINT, sid, H5P_DEFAULT, H5P_DEFAULT);
     CHECK(attr, H5I_INVALID_HID, "H5Acreate2");
 
-    for(i = 0; i < SPACE1_DIM1; i++)
-        wbuf[i] = (i * 3) + 1;
+    for(tu32 = (unsigned *)wbuf, i = 0; i < SPACE1_DIM1; i++)
+        *tu32++ = (unsigned)((i * 3) + 1);
 
     /* Write attribute to disk */
     ret = H5Awrite(attr, H5T_NATIVE_UINT, wbuf);
@@ -1874,8 +1873,8 @@ test_reference_external(void)
     attr = H5Acreate2(dataset, "Attr1", H5T_NATIVE_UINT, sid, H5P_DEFAULT, H5P_DEFAULT);
     CHECK(attr, H5I_INVALID_HID, "H5Acreate2");
 
-    for(i = 0; i < SPACE1_DIM1; i++)
-        wbuf[i] = i * 3;
+    for(tu32 = (unsigned *)wbuf, i = 0; i < SPACE1_DIM1; i++)
+        *tu32++ = (unsigned)(i * 3);
 
     /* Write attribute to disk */
     ret = H5Awrite(attr, H5T_NATIVE_UINT, wbuf);
@@ -1919,8 +1918,8 @@ test_reference_external(void)
     attr = H5Acreate2(tid, "Attr3", H5T_NATIVE_UINT, sid, H5P_DEFAULT, H5P_DEFAULT);
     CHECK(attr, H5I_INVALID_HID, "H5Acreate2");
 
-    for(i = 0; i < SPACE1_DIM1; i++)
-        wbuf[i] = (i * 3) + 2;
+    for(tu32 = (unsigned *)wbuf, i = 0; i < SPACE1_DIM1; i++)
+        *tu32++ = (unsigned)((i * 3) + 2);
 
     /* Write attribute to disk */
     ret = H5Awrite(attr, H5T_NATIVE_UINT, wbuf);
@@ -1941,28 +1940,28 @@ test_reference_external(void)
     /* Create reference to dataset1 attribute */
     ret = H5Rcreate_attr(fid1, "/Group1/Dataset1", "Attr1", &ref_wbuf[0]);
     CHECK(ret, FAIL, "H5Rcreate_attr");
-    ret = H5Rget_obj_type3(&ref_wbuf[0], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3((const H5R_ref_t *)&ref_wbuf[0], H5P_DEFAULT, &obj_type);
     CHECK(ret, FAIL, "H5Rget_obj_type3");
     VERIFY(obj_type, H5O_TYPE_DATASET, "H5Rget_obj_type3");
 
     /* Create reference to dataset2 attribute */
     ret = H5Rcreate_attr(fid1, "/Group1/Dataset2", "Attr1", &ref_wbuf[1]);
     CHECK(ret, FAIL, "H5Rcreate_attr");
-    ret = H5Rget_obj_type3(&ref_wbuf[1], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3((const H5R_ref_t *)&ref_wbuf[1], H5P_DEFAULT, &obj_type);
     CHECK(ret, FAIL, "H5Rget_obj_type3");
     VERIFY(obj_type, H5O_TYPE_DATASET, "H5Rget_obj_type3");
 
     /* Create reference to group attribute */
     ret = H5Rcreate_attr(fid1, "/Group1", "Attr2", &ref_wbuf[2]);
     CHECK(ret, FAIL, "H5Rcreate_attr");
-    ret = H5Rget_obj_type3(&ref_wbuf[2], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3((const H5R_ref_t *)&ref_wbuf[2], H5P_DEFAULT, &obj_type);
     CHECK(ret, FAIL, "H5Rget_obj_type3");
     VERIFY(obj_type, H5O_TYPE_GROUP, "H5Rget_obj_type3");
 
     /* Create reference to named datatype attribute */
     ret = H5Rcreate_attr(fid1, "/Group1/Datatype1", "Attr3", &ref_wbuf[3]);
     CHECK(ret, FAIL, "H5Rcreate_attr");
-    ret = H5Rget_obj_type3(&ref_wbuf[3], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3((const H5R_ref_t *)&ref_wbuf[3], H5P_DEFAULT, &obj_type);
     CHECK(ret, FAIL, "H5Rget_obj_type3");
     VERIFY(obj_type, H5O_TYPE_NAMED_DATATYPE, "H5Rget_obj_type3");
 
@@ -2015,7 +2014,7 @@ test_reference_external(void)
     CHECK(ret, FAIL, "H5Dread");
 
     /* Open attribute on dataset object */
-    attr = H5Ropen_attr(&ref_rbuf[0], H5P_DEFAULT, H5P_DEFAULT);
+    attr = H5Ropen_attr((const H5R_ref_t *)&ref_rbuf[0], H5P_DEFAULT, H5P_DEFAULT);
     CHECK(attr, H5I_INVALID_HID, "H5Ropen_attr");
 
     /* Check information in referenced dataset */
@@ -2029,38 +2028,38 @@ test_reference_external(void)
     ret = H5Aread(attr, H5T_NATIVE_UINT, rbuf);
     CHECK(ret, FAIL, "H5Aread");
 
-    for(i = 0; i < SPACE1_DIM1; i++)
-        VERIFY(rbuf[i], i * 3, "Data");
+    for(tu32 = (unsigned *)rbuf, i = 0; i < SPACE1_DIM1; i++, tu32++)
+        VERIFY(*tu32, (uint32_t)(i * 3), "Data");
 
     /* Close dereferenced Dataset */
     ret = H5Aclose(attr);
     CHECK(ret, FAIL, "H5Aclose");
 
     /* Open attribute on group object */
-    attr = H5Ropen_attr(&ref_rbuf[2], H5P_DEFAULT, H5P_DEFAULT);
+    attr = H5Ropen_attr((const H5R_ref_t *)&ref_rbuf[2], H5P_DEFAULT, H5P_DEFAULT);
     CHECK(attr, H5I_INVALID_HID, "H5Ropen_attr");
 
     /* Read from disk */
     ret = H5Aread(attr, H5T_NATIVE_UINT, rbuf);
     CHECK(ret, FAIL, "H5Aread");
 
-    for(i = 0; i < SPACE1_DIM1; i++)
-        VERIFY(rbuf[i], (i * 3) + 1, "Data");
+    for(tu32 = (unsigned *)rbuf, i = 0; i < SPACE1_DIM1; i++, tu32++)
+        VERIFY(*tu32, (uint32_t)((i * 3) + 1), "Data");
 
     /* Close attribute  */
     ret = H5Aclose(attr);
     CHECK(ret, FAIL, "H5Aclose");
 
     /* Open attribute on named datatype object */
-    attr = H5Ropen_attr(&ref_rbuf[3], H5P_DEFAULT, H5P_DEFAULT);
+    attr = H5Ropen_attr((const H5R_ref_t *)&ref_rbuf[3], H5P_DEFAULT, H5P_DEFAULT);
     CHECK(attr, H5I_INVALID_HID, "H5Ropen_attr");
 
     /* Read from disk */
     ret = H5Aread(attr, H5T_NATIVE_UINT, rbuf);
     CHECK(ret, FAIL, "H5Aread");
 
-    for(i = 0; i < SPACE1_DIM1; i++)
-        VERIFY(rbuf[i], (i * 3) + 2, "Data");
+    for(tu32 = (unsigned *)rbuf, i = 0; i < SPACE1_DIM1; i++, tu32++)
+        VERIFY(*tu32, (uint32_t)((i * 3) + 2), "Data");
 
     /* Close attribute  */
     ret = H5Aclose(attr);
@@ -2103,7 +2102,7 @@ test_reference_compat_conv(void)
     hid_t   tid1, tid2;         /* Datatype ID              */
     hsize_t dims1[] = {SPACE1_DIM1},
             dims2[] = {SPACE2_DIM1, SPACE2_DIM2},
-            dims3[] = {2};
+            dims3[] = {SPACE1_DIM1}; /* Purposedly set dimension larger to test NULL references */
     hsize_t start[SPACE2_RANK]; /* Starting location of hyperslab */
     hsize_t stride[SPACE2_RANK];/* Stride of hyperslab      */
     hsize_t count[SPACE2_RANK]; /* Element count of hyperslab */
@@ -2122,9 +2121,9 @@ test_reference_compat_conv(void)
 
     /* Allocate write & read buffers */
     wbuf_obj = (hobj_ref_t *)HDcalloc(sizeof(hobj_ref_t), SPACE1_DIM1);
-    rbuf_obj = HDcalloc(sizeof(H5R_ref_t), SPACE1_DIM1);
-    wbuf_reg = (hdset_reg_ref_t *)HDcalloc(sizeof(hdset_reg_ref_t), 2);
-    rbuf_reg = HDcalloc(sizeof(H5R_ref_t), 2);
+    rbuf_obj = (H5R_ref_t *)HDcalloc(sizeof(H5R_ref_t), SPACE1_DIM1);
+    wbuf_reg = (hdset_reg_ref_t *)HDcalloc(sizeof(hdset_reg_ref_t), SPACE1_DIM1);
+    rbuf_reg = (H5R_ref_t *)HDcalloc(sizeof(H5R_ref_t), SPACE1_DIM1);
 
     /* Create file */
     fid1 = H5Fcreate(FILE_REF_COMPAT, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
@@ -2287,43 +2286,43 @@ test_reference_compat_conv(void)
     CHECK(ret, FAIL, "H5Dread");
 
     /* Verify type of objects pointed at */
-    ret = H5Rget_obj_type3(&rbuf_obj[0], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3((const H5R_ref_t *)&rbuf_obj[0], H5P_DEFAULT, &obj_type);
     CHECK(ret, FAIL, "H5Rget_obj_type3");
     VERIFY(obj_type, H5O_TYPE_DATASET, "H5Rget_obj_type3");
 
-    ret = H5Rget_obj_type3(&rbuf_obj[1], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3((const H5R_ref_t *)&rbuf_obj[1], H5P_DEFAULT, &obj_type);
     CHECK(ret, FAIL, "H5Rget_obj_type3");
     VERIFY(obj_type, H5O_TYPE_DATASET, "H5Rget_obj_type3");
 
-    ret = H5Rget_obj_type3(&rbuf_obj[2], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3((const H5R_ref_t *)&rbuf_obj[2], H5P_DEFAULT, &obj_type);
     CHECK(ret, FAIL, "H5Rget_obj_type3");
     VERIFY(obj_type, H5O_TYPE_GROUP, "H5Rget_obj_type3");
 
-    ret = H5Rget_obj_type3(&rbuf_obj[3], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3((const H5R_ref_t *)&rbuf_obj[3], H5P_DEFAULT, &obj_type);
     CHECK(ret, FAIL, "H5Rget_obj_type3");
     VERIFY(obj_type, H5O_TYPE_NAMED_DATATYPE, "H5Rget_obj_type3");
 
 
     /* Make sure the referenced objects can be opened */
-    dset2 = H5Ropen_object(&rbuf_obj[0], H5P_DEFAULT, H5P_DEFAULT);
+    dset2 = H5Ropen_object((const H5R_ref_t *)&rbuf_obj[0], H5P_DEFAULT, H5P_DEFAULT);
     CHECK(dset2, H5I_INVALID_HID, "H5Ropen_object");
 
     ret = H5Dclose(dset2);
     CHECK(ret, FAIL, "H5Dclose");
 
-    dset2 = H5Ropen_object(&rbuf_obj[1], H5P_DEFAULT, H5P_DEFAULT);
+    dset2 = H5Ropen_object((const H5R_ref_t *)&rbuf_obj[1], H5P_DEFAULT, H5P_DEFAULT);
     CHECK(dset2, H5I_INVALID_HID, "H5Ropen_object");
 
     ret = H5Dclose(dset2);
     CHECK(ret, FAIL, "H5Dclose");
 
-    group2 = H5Ropen_object(&rbuf_obj[2], H5P_DEFAULT, H5P_DEFAULT);
+    group2 = H5Ropen_object((const H5R_ref_t *)&rbuf_obj[2], H5P_DEFAULT, H5P_DEFAULT);
     CHECK(group2, H5I_INVALID_HID, "H5Ropen_object");
 
     ret = H5Gclose(group2);
     CHECK(ret, FAIL, "H5Gclose");
 
-    tid2 = H5Ropen_object(&rbuf_obj[3], H5P_DEFAULT, H5P_DEFAULT);
+    tid2 = H5Ropen_object((const H5R_ref_t *)&rbuf_obj[3], H5P_DEFAULT, H5P_DEFAULT);
     CHECK(tid2, H5I_INVALID_HID, "H5Ropen_object");
 
     ret = H5Tclose(tid2);
@@ -2343,22 +2342,22 @@ test_reference_compat_conv(void)
     CHECK(ret, FAIL, "H5Dread");
 
     /* Verify type of objects pointed at */
-    ret = H5Rget_obj_type3(&rbuf_reg[0], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3((const H5R_ref_t *)&rbuf_reg[0], H5P_DEFAULT, &obj_type);
     CHECK(ret, FAIL, "H5Rget_obj_type3");
     VERIFY(obj_type, H5O_TYPE_DATASET, "H5Rget_obj_type3");
 
-    ret = H5Rget_obj_type3(&rbuf_reg[1], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3((const H5R_ref_t *)&rbuf_reg[1], H5P_DEFAULT, &obj_type);
     CHECK(ret, FAIL, "H5Rget_obj_type3");
     VERIFY(obj_type, H5O_TYPE_DATASET, "H5Rget_obj_type3");
 
     /* Make sure the referenced objects can be opened */
-    dset2 = H5Ropen_object(&rbuf_reg[0], H5P_DEFAULT, H5P_DEFAULT);
+    dset2 = H5Ropen_object((const H5R_ref_t *)&rbuf_reg[0], H5P_DEFAULT, H5P_DEFAULT);
     CHECK(dset2, H5I_INVALID_HID, "H5Ropen_object");
 
     ret = H5Dclose(dset2);
     CHECK(ret, FAIL, "H5Dclose");
 
-    dset2 = H5Ropen_object(&rbuf_reg[1], H5P_DEFAULT, H5P_DEFAULT);
+    dset2 = H5Ropen_object((const H5R_ref_t *)&rbuf_reg[1], H5P_DEFAULT, H5P_DEFAULT);
     CHECK(dset2, H5I_INVALID_HID, "H5Ropen_object");
 
     ret = H5Dclose(dset2);
@@ -2415,8 +2414,8 @@ test_reference_perf(void)
                *rbuf_deprec;/* deprecated references            */
     hdset_reg_ref_t *wbuf_reg_deprec,   /* deprecated references*/
                *rbuf_reg_deprec;        /* deprecated references*/
-    unsigned *ibuf, *obuf;
-    unsigned i, j;       /* Counters                         */
+    unsigned   *tu32;       /* Temporary pointer to uint32 data */
+    int         i, j;       /* Counters                         */
     H5O_type_t  obj_type;   /* Object type                      */
     herr_t      ret;        /* Generic return value             */
     double      t1, t2, t;  /* Timers                           */
@@ -2425,20 +2424,18 @@ test_reference_perf(void)
     MESSAGE(5, ("Testing Object Reference Performance\n"));
 
     /* Allocate write & read buffers */
-    wbuf = HDcalloc(sizeof(H5R_ref_t), SPACE1_DIM1);
-    obuf = HDcalloc(sizeof(unsigned), SPACE1_DIM1);
-    ibuf = HDcalloc(sizeof(unsigned), SPACE1_DIM1);
-    wbuf_deprec = (hobj_ref_t *)HDcalloc(sizeof(hobj_ref_t), SPACE1_DIM1);
-    rbuf = (H5R_ref_t *)HDcalloc(sizeof(H5R_ref_t), SPACE1_DIM1);
-    rbuf_deprec = (hobj_ref_t *)HDcalloc(sizeof(hobj_ref_t), SPACE1_DIM1);
-    tbuf = (H5R_ref_t *)HDcalloc(sizeof(H5R_ref_t), SPACE1_DIM1);
-    wbuf_reg = (H5R_ref_t *)HDcalloc(sizeof(H5R_ref_t), SPACE1_DIM1);
-    rbuf_reg = (H5R_ref_t *)HDcalloc(sizeof(H5R_ref_t), SPACE1_DIM1);
-    wbuf_reg_deprec = (hdset_reg_ref_t *)HDcalloc(sizeof(hdset_reg_ref_t), SPACE1_DIM1);
-    rbuf_reg_deprec = (hdset_reg_ref_t *)HDcalloc(sizeof(hdset_reg_ref_t), SPACE1_DIM1);
-
-    for(i = 0; i < SPACE1_DIM1; i++)
-        obuf[i] = i * 3;
+    wbuf = (H5R_ref_t *)HDcalloc(MAX(sizeof(unsigned), sizeof(H5R_ref_t)), SPACE1_DIM1);
+    wbuf_deprec = (hobj_ref_t *)HDcalloc(MAX(sizeof(unsigned), sizeof(hobj_ref_t)), SPACE1_DIM1);
+    rbuf = (H5R_ref_t *)HDcalloc(MAX(sizeof(unsigned), sizeof(H5R_ref_t)), SPACE1_DIM1);
+    rbuf_deprec = (hobj_ref_t *)HDcalloc(MAX(sizeof(unsigned), sizeof(hobj_ref_t)), SPACE1_DIM1);
+    tbuf = (H5R_ref_t *)HDcalloc(MAX(sizeof(unsigned), sizeof(H5R_ref_t)), SPACE1_DIM1);
+    wbuf_reg = (H5R_ref_t *)HDcalloc(MAX(sizeof(unsigned), sizeof(H5R_ref_t)), SPACE1_DIM1);
+    rbuf_reg = (H5R_ref_t *)HDcalloc(MAX(sizeof(unsigned), sizeof(H5R_ref_t)), SPACE1_DIM1);
+    wbuf_reg_deprec = (hdset_reg_ref_t *)HDcalloc(MAX(sizeof(unsigned), sizeof(hdset_reg_ref_t)), SPACE1_DIM1);
+    rbuf_reg_deprec = (hdset_reg_ref_t *)HDcalloc(MAX(sizeof(unsigned), sizeof(hdset_reg_ref_t)), SPACE1_DIM1);
+
+    for(tu32 = (unsigned *)wbuf, i = 0; i < SPACE1_DIM1; i++)
+        *tu32++ = (unsigned)i * 3;
 
     /* Create file */
     fid1 = H5Fcreate(FILE_REF_OBJ, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
@@ -2461,7 +2458,7 @@ test_reference_perf(void)
     CHECK(dataset, H5I_INVALID_HID, "H5Dcreate2");
 
     /* Write selection to disk */
-    ret = H5Dwrite(dataset, H5T_NATIVE_UINT, H5S_ALL, H5S_ALL, H5P_DEFAULT, obuf);
+    ret = H5Dwrite(dataset, H5T_NATIVE_UINT, H5S_ALL, H5S_ALL, H5P_DEFAULT, wbuf);
     CHECK(ret, FAIL, "H5Dwrite");
 
     /* Close Dataset */
@@ -2521,7 +2518,7 @@ test_reference_perf(void)
     /* Create reference to dataset */
     ret = H5Rcreate_object(fid1, "/Group1/Dataset1", &wbuf[0]);
     CHECK(ret, FAIL, "H5Rcreate_object");
-    ret = H5Rget_obj_type3(&wbuf[0], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3((const H5R_ref_t *)&wbuf[0], H5P_DEFAULT, &obj_type);
     CHECK(ret, FAIL, "H5Rget_obj_type3");
     VERIFY(obj_type, H5O_TYPE_DATASET, "H5Rget_obj_type3");
 
@@ -2673,7 +2670,7 @@ test_reference_perf(void)
     CHECK(ret, FAIL, "H5Dread");
 
     /* Open dataset object */
-    dset2 = H5Ropen_object(&rbuf[0], H5P_DEFAULT, dapl_id);
+    dset2 = H5Ropen_object((const H5R_ref_t *)&rbuf[0], H5P_DEFAULT, dapl_id);
     CHECK(dset2, H5I_INVALID_HID, "H5Ropen_object");
 
     /* Check information in referenced dataset */
@@ -2684,11 +2681,11 @@ test_reference_perf(void)
     VERIFY(ret, dims1[0], "H5Sget_simple_extent_npoints");
 
     /* Read from disk */
-    ret = H5Dread(dset2, H5T_NATIVE_UINT, H5S_ALL, H5S_ALL, H5P_DEFAULT, ibuf);
+    ret = H5Dread(dset2, H5T_NATIVE_UINT, H5S_ALL, H5S_ALL, H5P_DEFAULT, tbuf);
     CHECK(ret, FAIL, "H5Dread");
 
-    for(i = 0; i < dims1[0]; i++)
-        VERIFY(ibuf[i], i * 3, "Data");
+    for(tu32 = (unsigned *)tbuf, i = 0; i < (int)dims1[0]; i++, tu32++)
+        VERIFY(*tu32, (uint32_t)(i*3), "Data");
 
     /* Close dereferenced Dataset */
     ret = H5Dclose(dset2);
@@ -2770,7 +2767,7 @@ test_reference_perf(void)
     CHECK(ret, FAIL, "H5Fclose");
 
     /* Destroy references */
-    for(j = 0; j < dims1[0]; j++) {
+    for(j = 0; j < (int)dims1[0]; j++) {
         ret = H5Rdestroy(&wbuf[j]);
         CHECK(ret, FAIL, "H5Rdestroy");
         ret = H5Rdestroy(&wbuf_reg[j]);
@@ -2791,8 +2788,6 @@ test_reference_perf(void)
     HDfree(wbuf_reg_deprec);
     HDfree(rbuf_reg_deprec);
     HDfree(tbuf);
-    HDfree(ibuf);
-    HDfree(obuf);
 }   /* test_reference_perf() */
 
 /****************************************************************
diff --git a/test/trefer_deprec.c b/test/trefer_deprec.c
index 1b77e9c..949f41b 100644
--- a/test/trefer_deprec.c
+++ b/test/trefer_deprec.c
@@ -517,7 +517,7 @@ test_reference_region(H5F_libver_t libver_low, H5F_libver_t libver_high)
     hsize_t high[SPACE2_RANK];  /* Selection bounds */
     hdset_reg_ref_t *wbuf,      /* buffer to write to disk */
                     *rbuf;      /* buffer read from disk */
-    hdset_reg_ref_t  nvrbuf[3]={{{0}},{{101}},{{255}}}; /* buffer with non-valid refs */
+    hdset_reg_ref_t  nvrbuf[3]={{0},{101},{255}}; /* buffer with non-valid refs */
     uint8_t *dwbuf,             /* Buffer for writing numeric data to disk */
             *drbuf;             /* Buffer for reading numeric data from disk */
     uint8_t *tu8;               /* Temporary pointer to uint8 data */
diff --git a/test/tvlstr.c b/test/tvlstr.c
index cc01084..731270c 100644
--- a/test/tvlstr.c
+++ b/test/tvlstr.c
@@ -861,12 +861,12 @@ static void test_write_same_element(void)
     hid_t   file1, dataset1;
     hid_t   mspace, fspace, dtype;
     hsize_t fdim[] = {SPACE1_DIM1};
-    const char *val[SPACE1_DIM1] = {"But", "reuniting", "is a", "great joy"};
+    char *val[SPACE1_DIM1] = {"But", "reuniting", "is a", "great joy"};
     hsize_t marray[] = {NUMP};
     hsize_t coord[SPACE1_RANK][NUMP];
     herr_t ret;
 
-    const char *wdata[SPACE1_DIM1] = {"Parting", "is such a", "sweet", "sorrow."};
+    char *wdata[SPACE1_DIM1] = {"Parting", "is such a", "sweet", "sorrow."};
 
     file1 = H5Fcreate(DATAFILE3, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
     CHECK(file1, FAIL, "H5Fcreate");
diff --git a/test/vds_swmr.h b/test/vds_swmr.h
index 18d6b35..eb2dcf4 100644
--- a/test/vds_swmr.h
+++ b/test/vds_swmr.h
@@ -84,17 +84,31 @@
 #define N_PLANES_TO_WRITE   25
 
 /* Planes */
-extern hsize_t PLANES[N_SOURCES][RANK];
+static hsize_t PLANES[N_SOURCES][RANK] = {
+    {1, SM_HEIGHT, WIDTH},
+    {1, LG_HEIGHT, WIDTH},
+    {1, SM_HEIGHT, WIDTH},
+    {1, LG_HEIGHT, WIDTH},
+    {1, SM_HEIGHT, WIDTH},
+    {1, LG_HEIGHT, WIDTH}
+};
 
 /* File names for source datasets */
-extern char FILE_NAMES[N_SOURCES][NAME_LEN];
+static char FILE_NAMES[N_SOURCES][NAME_LEN] = {
+    {"vds_swmr_src_a.h5"},
+    {"vds_swmr_src_b.h5"},
+    {"vds_swmr_src_c.h5"},
+    {"vds_swmr_src_d.h5"},
+    {"vds_swmr_src_e.h5"},
+    {"vds_swmr_src_f.h5"}
+};
 
 /* VDS file name */
-extern char VDS_FILE_NAME[NAME_LEN];
+static char VDS_FILE_NAME[NAME_LEN] = "vds_swmr.h5";
 
 /* Dataset names */
-extern char SOURCE_DSET_PATH[NAME_LEN];
-extern char VDS_DSET_NAME[NAME_LEN];
+static char SOURCE_DSET_PATH[NAME_LEN] = "/source_dset";
+static char VDS_DSET_NAME[NAME_LEN]    = "vds_dset";
 
 /* Fill values */
 #endif /* VDS_SWMR_H */
diff --git a/test/vds_swmr_common.c b/test/vds_swmr_common.c
deleted file mode 100644
index d2b4bd6..0000000
--- a/test/vds_swmr_common.c
+++ /dev/null
@@ -1,36 +0,0 @@
-/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
- * Copyright by The HDF Group.                                               *
- * Copyright by the Board of Trustees of the University of Illinois.         *
- * All rights reserved.                                                      *
- *                                                                           *
- * This file is part of HDF5.  The full HDF5 copyright notice, including     *
- * terms governing use, modification, and redistribution, is contained in    *
- * the COPYING file, which can be found at the root of the source code       *
- * distribution tree, or in https://support.hdfgroup.org/ftp/HDF5/releases.  *
- * If you do not have access to either file, you may request a copy from     *
- * help@hdfgroup.org.                                                        *
- * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
-
-#include "vds_swmr.h"
-
-hsize_t PLANES[N_SOURCES][RANK] = {
-    {1, SM_HEIGHT, WIDTH},
-    {1, LG_HEIGHT, WIDTH},
-    {1, SM_HEIGHT, WIDTH},
-    {1, LG_HEIGHT, WIDTH},
-    {1, SM_HEIGHT, WIDTH},
-    {1, LG_HEIGHT, WIDTH}
-};
-
-char FILE_NAMES[N_SOURCES][NAME_LEN] = {
-    {"vds_swmr_src_a.h5"},
-    {"vds_swmr_src_b.h5"},
-    {"vds_swmr_src_c.h5"},
-    {"vds_swmr_src_d.h5"},
-    {"vds_swmr_src_e.h5"},
-    {"vds_swmr_src_f.h5"}
-};
-
-char VDS_FILE_NAME[NAME_LEN] = "vds_swmr.h5";
-char SOURCE_DSET_PATH[NAME_LEN] = "/source_dset";
-char VDS_DSET_NAME[NAME_LEN]    = "vds_dset";
diff --git a/tools/lib/h5diff.c b/tools/lib/h5diff.c
index 1b4bc56..c2153e5 100644
--- a/tools/lib/h5diff.c
+++ b/tools/lib/h5diff.c
@@ -258,8 +258,6 @@ free_exclude_path_list(diff_opt_t *opts)
  * Parameter:
  *           table_out [OUT] : return the list
  *------------------------------------------------------------------------*/
-#pragma GCC diagnostic push
-#pragma GCC diagnostic warning "-Wunused-but-set-variable"
 static void
 build_match_list (const char *objname1, trav_info_t *info1, const char *objname2, trav_info_t *info2,
         trav_table_t ** table_out, diff_opt_t *opts)
@@ -376,7 +374,6 @@ done:
     *table_out = table;
     h5difftrace("build_match_list finish\n");
 }
-#pragma GCC diagnostic pop
 
 
 /*-------------------------------------------------------------------------
diff --git a/tools/lib/h5diff_array.c b/tools/lib/h5diff_array.c
index 55ad65c..2a45913 100644
--- a/tools/lib/h5diff_array.c
+++ b/tools/lib/h5diff_array.c
@@ -2245,9 +2245,6 @@ static hsize_t character_compare(char *mem1, char *mem2, hsize_t i, size_t u,
  *-------------------------------------------------------------------------
  */
 
-#pragma GCC diagnostic push
-#pragma GCC diagnostic warning "-Wunused-but-set-variable"
-
 static hsize_t character_compare_opt(unsigned char *mem1, unsigned char *mem2,
         hsize_t i, int rank, hsize_t *dims, hsize_t *acc, hsize_t *pos, diff_opt_t *opts, const char *obj1, const char *obj2, int *ph)
 {
@@ -2308,7 +2305,6 @@ static hsize_t character_compare_opt(unsigned char *mem1, unsigned char *mem2,
 
     return nfound;
 }
-#pragma GCC diagnostic pop
 
 /*-------------------------------------------------------------------------
  * Function: diff_float
diff --git a/tools/lib/h5tools_utils.c b/tools/lib/h5tools_utils.c
index 6fc9de4..47ce690 100644
--- a/tools/lib/h5tools_utils.c
+++ b/tools/lib/h5tools_utils.c
@@ -1279,7 +1279,7 @@ done:
 int
 h5tools_set_configured_fapl(hid_t      fapl_id,
                            const char  vfd_name[],
-                           void       *fapl_t_ptr H5_ATTR_UNUSED)
+                           void       *fapl_t_ptr)
 {
     int ret_value = 1;
 
diff --git a/tools/src/h5import/h5import.c b/tools/src/h5import/h5import.c
index 65c2359..1eef5ab 100644
--- a/tools/src/h5import/h5import.c
+++ b/tools/src/h5import/h5import.c
@@ -1428,7 +1428,7 @@ static int processConfigurationFile(char *infile, struct Input *in)
     /* Initialize machine endian */
     volatile uint32_t ibyte=0x01234567;
     /* 0 for big endian, 1 for little endian. */
-    if ((*((volatile uint8_t*)(&ibyte))) == 0x67) {
+    if ((*((uint8_t*)(&ibyte))) == 0x67) {
         if ((kindex = OutputByteOrderStrToInt("LE")) == -1) {
             (void) HDfprintf(stderr, "%s", err11e);
             return (-1);
diff --git a/tools/src/h5repack/h5repack_main.c b/tools/src/h5repack/h5repack_main.c
index 16899a3..c628beb 100644
--- a/tools/src/h5repack/h5repack_main.c
+++ b/tools/src/h5repack/h5repack_main.c
@@ -281,7 +281,7 @@ int read_info(const char *filename, pack_opt_t *options)
     char comp_info[1024];
     FILE *fp = NULL;
     char c;
-    int i;
+    int i, rc = 1;
     int ret_value = EXIT_SUCCESS;
 
     if (NULL == (fp = HDfopen(filename, "r"))) {
@@ -412,7 +412,7 @@ set_sort_order(const char *form)
 static
 int parse_command_line(int argc, const char **argv, pack_opt_t* options)
 {
-    int bound, opt;
+    int opt;
     int ret_value = 0;
 
     /* parse command line options */
@@ -492,21 +492,19 @@ int parse_command_line(int argc, const char **argv, pack_opt_t* options)
                 break;
 
             case 'j':
-                bound = HDatoi(opt_arg);
-                if (bound < H5F_LIBVER_EARLIEST || bound > H5F_LIBVER_LATEST) {
+                options->low_bound = (H5F_libver_t)HDatoi(opt_arg);
+                if (options->low_bound < H5F_LIBVER_EARLIEST || options->low_bound > H5F_LIBVER_LATEST) {
                     error_msg("in parsing low bound\n");
                     goto done;
                 }
-                options->low_bound = bound;
                 break;
 
             case 'k':
-                bound = HDatoi(opt_arg);
-                if (bound < H5F_LIBVER_EARLIEST || bound > H5F_LIBVER_LATEST) {
+                options->high_bound = (H5F_libver_t)HDatoi(opt_arg);
+                if (options->high_bound < H5F_LIBVER_EARLIEST || options->high_bound > H5F_LIBVER_LATEST) {
                     error_msg("in parsing high bound\n");
                     goto done;
                 }
-                options->high_bound = bound;
                 break;
 
             case 'c':
diff --git a/tools/test/h5repack/h5repackgentest.c b/tools/test/h5repack/h5repackgentest.c
index 87ca31c..aaac285 100644
--- a/tools/test/h5repack/h5repackgentest.c
+++ b/tools/test/h5repack/h5repackgentest.c
@@ -314,6 +314,7 @@ generate_f32le(hbool_t external) {
 int
 main(void) {
     int i = 0;
+    int ret_value = 0;
 
     for (i = 0; i < 2; i++) {
         hbool_t external = (i & 1) ? TRUE : FALSE;