Merge pull request #2030 in HDFFV/hdf5 from ~DYOUNG/vchoi_fork:add-werror-and-squash-some to develop

* commit '62208b056a09c01855fbac7f75146be58ad6bfe5': (44 commits)
  Add an #include to get a function declaration.
  Don't use C99 designated initializers, they're not compatible with Visual Studio 2010.
  Quiet some more maybe-uninitialized warnings---each is a false positive, *sigh*.  This is more code that may not compile with VS2010, *sigh sigh*.
  Always warn on maybe-uninitialized.  -Wincompatible-pointer-types was not available until GCC 5, so enable it only if that's the GCC version we're using.
  Only promote maybe-uninitialized warnings to errors on GCC 8.  Even on GCC 8, there may be false positives at low optimization levels?  I need to check.
  Only use -Werror=cast-function-type with GCC 8 and later.
  Put all of the -W options back into the order I found them in so that it's easier to compare old and new config/gnu-flags.
  Add new source files to CMakeLists.txt.
  Mention the -Werror= flags in libhdf5.settings.in.
  free -> HDfree
  Promote decleration-after-statement warnings to errors.
  Quiet decleration-after-statement warnings.
  Move a statement under some declarations since some vintages of Visual Studio don't like declarations after statements.
  Document H5D__chunk_mem_xfree_wrapper().
  Undo accidental test deletion.
  Oops, delete a debug printf that snuck in here.
  Undo my changes to the HD macros, hadn't really intended those to be on this branch....
  Make errors of some more warnings.  Move disabled warnings to DEVELOPER_WARNING_CFLAGS.  Put just one warning option on a line, and sort some of the options.
  Cast to the parameter type, H5VL_token_t *, instead of to unsigned char *.
  Change hdset_reg_ref_t and H5R_ref_t from arrays of unsigned char to structs containing those arrays.  Encapsulating the arrays in this way makes it easier to write and think about pointers to these types, casts to/from these types, etc.
  ...

52 files changed, 498 insertions, 314 deletions

diff --git a/config/commence.am b/config/commence.am
index a16eee5..830c494 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@
+AM_CFLAGS=@AM_CFLAGS@ @H5_CFLAGS@ @H5_ECFLAGS@
 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 6355ccf..bc120a8 100644
--- a/config/gnu-flags
+++ b/config/gnu-flags
@@ -168,12 +168,44 @@ 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 -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="$H5_CFLAGS -Wundef -Wunused-macros -Wunsafe-loop-optimizations -Wwrite-strings"
+    H5_CFLAGS="$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"
 
     ######################
     # Developer warnings #
@@ -222,17 +254,34 @@ 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 -Wlarger-than=2560"                   
+        H5_CFLAGS="$H5_CFLAGS -Wlogical-op"
+        #
+        # Lots of noise, questionable benefit:
+        #
+        DEVELOPER_WARNING_CFLAGS="$DEVELOPER_WARNING_CFLAGS -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 -Wframe-larger-than=16384 -Wpacked-bitfield-compat"
+        H5_CFLAGS="$H5_CFLAGS -Wsync-nand -Wpacked-bitfield-compat"
+        #
+        # Lots of noise, questionable benefit:
+        #
+        DEVELOPER_WARNING_CFLAGS="$DEVELOPER_WARNING_CFLAGS -Wframe-larger-than=16384"
+        #
     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 -Wjump-misses-init -Wunsuffixed-float-constants"
+        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"
+        #
     fi
 
     # gcc 4.6
@@ -244,7 +293,17 @@ 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 $cc_vers_minor -ge 7; then
-        H5_CFLAGS="$H5_CFLAGS -Wstack-usage=8192 -Wvector-operation-performance"
+        #
+        # 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"
+
         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
@@ -263,11 +322,21 @@ 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 -Wnull-dereference -Wunused-const-variable -Wduplicated-cond -Whsa -Wnormalized"
+        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"
     fi
 
     # gcc 7
@@ -278,6 +347,13 @@ 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 0eada60..5851b32 100644
--- a/configure.ac
+++ b/configure.ac
@@ -103,7 +103,11 @@ 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 b24f887..44e0ecf9 100644
--- a/hl/src/H5DS.c
+++ b/hl/src/H5DS.c
@@ -1433,7 +1433,7 @@ herr_t H5DSset_label(hid_t did, unsigned int idx, const char *label)
     union {                    /* union is needed to eliminate compiler warnings about */
       char  ** buf;            /* discarding the 'const' qualifier in the free */
       char const ** const_buf; /* buf calls */
-    } u;
+    } u = {.buf = NULL, .const_buf = NULL};
     /*-------------------------------------------------------------------------
     * parameter checking
     *-------------------------------------------------------------------------
diff --git a/hl/test/H5srcdir_str.h.in b/hl/test/H5srcdir_str.h.in
index bab1df3..ba30a88 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 */
-static const char *config_srcdir = "@srcdir@";
+#define config_srcdir "@srcdir@"
 
diff --git a/src/H5Cdbg.c b/src/H5Cdbg.c
index 1f55e86..cb1d0e2 100644
--- a/src/H5Cdbg.c
+++ b/src/H5Cdbg.c
@@ -319,9 +319,8 @@ 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 = 0x%llx, item = %p\n",
-                      (unsigned long long)node_ptr,
-                      H5SL_item(node_ptr));
+            HDfprintf(stdout, "		node_ptr = %p, item = %p\n",
+                      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 9156c0d..b8648f0 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;
-    ssize_t			slist_size_increase;
+    int64_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 d605ef9..947f611 100644
--- a/src/H5Dchunk.c
+++ b/src/H5Dchunk.c
@@ -284,7 +284,8 @@ 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, const void *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_realloc(void *chk, size_t size,
     const H5O_pline_t *pline);
 static herr_t H5D__chunk_cinfo_cache_reset(H5D_chunk_cached_t *last);
@@ -1100,14 +1101,10 @@ 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		*/
 
@@ -1431,7 +1428,7 @@ H5D__chunk_mem_alloc(size_t size, const H5O_pline_t *pline)
  *-------------------------------------------------------------------------
  */
 static void *
-H5D__chunk_mem_xfree(void *chk, const void *_pline)
+H5D__chunk_mem_xfree(void *chk, void *_pline)
 {
     const H5O_pline_t *pline = (const H5O_pline_t *)_pline;
 
@@ -1447,6 +1444,17 @@ H5D__chunk_mem_xfree(void *chk, const 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
@@ -2140,12 +2148,6 @@ 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
@@ -2170,17 +2172,18 @@ 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) {
-            hssize_t    schunk_points;          /* Number of elements in chunk selection */
+            hsize_t    schunk_points;          /* Number of elements in chunk selection */
             hsize_t     tmp_count = 1;
 
             /* Get pointer to chunk's information */
@@ -4451,7 +4454,7 @@ 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, (H5MM_free_t)H5D__chunk_mem_xfree, (void *)pline,
+                (void *)pline, H5D__chunk_mem_xfree_wrapper, (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")
@@ -7153,7 +7156,6 @@ 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)
@@ -7163,7 +7165,6 @@ 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 819d200..0b954cf 100644
--- a/src/H5FDhdfs.c
+++ b/src/H5FDhdfs.c
@@ -581,7 +581,6 @@ 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 ac5667f..1c7d549 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;
-    struct timeval stat_timeval_diff;
+    struct timeval open_timeval_diff = {0, 0};
+    struct timeval stat_timeval_diff = {0, 0};
 #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 df67bd9..cf4a587 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 flush_in_progress = FALSE;      /* Is flushing in progress */
+        hbool_t closing_or_flushing = f->shared->closing;      /* Is closing or flushing in progress */
 
-        /* Check whether cache is flush_in_progress */
-        if(H5AC_get_cache_flush_in_progress(f->shared->cache, &flush_in_progress) < 0)
+        /* 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)
             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(f->shared->closing || flush_in_progress) {
+                if(closing_or_flushing) {
                     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(f->shared->closing || flush_in_progress) {
+                    if(closing_or_flushing) {
                         if(fspace->sect_size > fspace->alloc_sect_size)
                             release_sinfo_space = TRUE;
                         else
diff --git a/src/H5Fsuper_cache.c b/src/H5Fsuper_cache.c
index 125d6cf..b7c1dad 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 = (const uint8_t *)_image;   			    /* Pointer into raw data buffer */
+    const uint8_t *image = _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
@@ -361,6 +361,15 @@ 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")
@@ -393,7 +402,7 @@ done:
 static htri_t
 H5F__cache_superblock_verify_chksum(const void *_image, size_t len, void *_udata)
 {
-    const uint8_t *image = (const uint8_t *)_image;    	/* Pointer into raw data buffer */
+    const uint8_t *image = _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 */
@@ -439,7 +448,7 @@ 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 = (const uint8_t *)_image;       /* Pointer into raw data buffer */
+    const uint8_t	*image = _image; /* Pointer into raw data buffer */
     H5F_super_t         *ret_value = NULL;      /* Return value */
 
     FUNC_ENTER_STATIC
@@ -664,7 +673,7 @@ 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 = (uint8_t *)_image;         /* Pointer into raw data buffer */
+    uint8_t *image = _image;         /* Pointer into raw data buffer */
     haddr_t rel_eof;            /* Relative EOF for file */
     herr_t ret_value = SUCCEED; /* Return value */
 
@@ -870,9 +879,9 @@ 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 = (const uint8_t *)_image;   			/* Pointer into raw data buffer */
+    const uint8_t *image = _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 */
+    H5O_drvinfo_t drvrinfo = {.len = 0};     /* Driver info */
     herr_t ret_value = SUCCEED; /* Return value */
 
     FUNC_ENTER_STATIC
@@ -916,7 +925,7 @@ 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 = (const uint8_t *)_image;       /* Pointer into raw data buffer */
+    const uint8_t	*image = _image; /* Pointer into raw data buffer */
     char                drv_name[9];    /* Name of driver */
     H5O_drvinfo_t       *ret_value = NULL;      /* Return value */
 
@@ -1010,7 +1019,7 @@ 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 = (uint8_t *)_image;         /* Pointer into raw data buffer */
+    uint8_t *image = _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 2d1c1f2..ab448ef 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 */
@@ -419,6 +419,12 @@ 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 0c27180..79d790b 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;                /* Encoded object size */
+    size_t enc_obj_size = 0;            /* 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 29e88df..e3d0f4c 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 = {.size = 0}; /* Global heap */
     herr_t ret_value = SUCCEED;         /* Return value */
 
     FUNC_ENTER_STATIC
@@ -217,6 +217,12 @@ 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/H5Oint.c b/src/H5Oint.c
index b97ff30..0029976 100644
--- a/src/H5Oint.c
+++ b/src/H5Oint.c
@@ -31,6 +31,7 @@
 /* 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 fe5be0f..59da91a 100644
--- a/src/H5Pmapl.c
+++ b/src/H5Pmapl.c
@@ -138,6 +138,7 @@ done:
 } /* end H5P__macc_reg_prop() */
 
 
+#ifdef H5_HAVE_MAP_API
 /*-------------------------------------------------------------------------
  * Function:    H5Pset_map_iterate_hints
  *
@@ -214,4 +215,4 @@ 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/H5Rint.c b/src/H5Rint.c
index 504ae06..9fbc7ef 100644
--- a/src/H5Rint.c
+++ b/src/H5Rint.c
@@ -1169,8 +1169,8 @@ 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)) {
-        p = (uint8_t *)buf;
         int rank;
+        p = (uint8_t *)buf;
 
         /* Encode the size for safety check */
         UINT32ENCODE(p, (uint32_t)buf_size);
diff --git a/src/H5Rpublic.h b/src/H5Rpublic.h
index ce54ac4..045e04a 100644
--- a/src/H5Rpublic.h
+++ b/src/H5Rpublic.h
@@ -70,14 +70,18 @@ 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 unsigned char hdset_reg_ref_t[H5R_DSET_REG_REF_BUF_SIZE];
+typedef struct {
+    unsigned char content[H5R_DSET_REG_REF_BUF_SIZE];
+} hdset_reg_ref_t;
 
 /**
  * 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 unsigned char H5R_ref_t[H5R_REF_BUF_SIZE];
+typedef struct {
+    unsigned char content[H5R_REF_BUF_SIZE];
+} H5R_ref_t;
 
 /********************/
 /* Public Variables */
diff --git a/src/H5SL.c b/src/H5SL.c
index 5f00fb8..ec06395 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;                            /* Return value */
+    void *ret_value = NULL;                     /* 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;                     /* Return value */
+    H5SL_node_t *ret_value = NULL;              /* Return value */
 
     FUNC_ENTER_NOAPI_NOINIT_NOERR
 
diff --git a/src/H5SM.c b/src/H5SM.c
index 290e575..91ef98b 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;
+    unsigned type_flag = 0;
     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;                 /* Flag corresponding to message type */
+    unsigned type_flag = 0;             /* Flag corresponding to message type */
     size_t u;                           /* Local index variable */
     htri_t ret_value = FALSE;           /* Return value */
 
diff --git a/src/H5T.c b/src/H5T.c
index 9263158..3fc59d0 100644
--- a/src/H5T.c
+++ b/src/H5T.c
@@ -3320,7 +3320,7 @@ done:
  *-------------------------------------------------------------------------
  */
 H5T_t *
-H5T_copy(H5T_t *old_dt, H5T_copy_t method)
+H5T_copy(const 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/H5Tprivate.h b/src/H5Tprivate.h
index d8e98af..86bc174 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(H5T_t *old_dt, H5T_copy_t method);
+H5_DLL H5T_t *H5T_copy(const 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 2e52954..b1bc9e8 100644
--- a/src/H5Tref.c
+++ b/src/H5Tref.c
@@ -709,7 +709,7 @@ H5T__ref_obj_disk_read(H5VL_object_t *src_file, const void *src_buf, size_t src_
 
     /* Get object address */
     if(H5R__decode_token_obj_compat((const unsigned char *)src_buf, &src_size,
-        (unsigned char *)dst_buf, H5F_SIZEOF_ADDR(src_f)) < 0)
+        (H5VL_token_t *)dst_buf, H5F_SIZEOF_ADDR(src_f)) < 0)
         HGOTO_ERROR(H5E_REFERENCE, H5E_CANTDECODE, FAIL, "unable to get object address")
 
 done:
diff --git a/src/libhdf5.settings.in b/src/libhdf5.settings.in
index 1591bed..0c2be75 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 C Flags: @H5_CFLAGS@ @H5_ECFLAGS@
                      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 c7a945e..d3f8ed8 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -16,9 +16,11 @@ 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
new file mode 100644
index 0000000..8268d2c
--- /dev/null
+++ b/test/H5srcdir.c
@@ -0,0 +1,61 @@
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+ * 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 32fe8c9..d0a4bf7 100644
--- a/test/H5srcdir.h
+++ b/test/H5srcdir.h
@@ -24,47 +24,16 @@
 #include "H5srcdir_str.h"
 
 /* Buffer to construct path in and return pointer to */
-static char srcdir_path[1024] = "";
+extern char srcdir_path[1024];
 
 /* Buffer to construct file in and return pointer to */
-static char srcdir_testpath[1024] = "";
+extern char srcdir_testpath[1024];
 
 /* Just return the srcdir path */
-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() */
+const char *H5_get_srcdir(void);
 
 /* Append the test file name to the srcdir path and return the whole string */
-static const char *H5_get_srcdir_filename(const char *filename)
-{
-    const char *srcdir = H5_get_srcdir();
+const char *H5_get_srcdir_filename(const char *);
 
-    /* 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 bab1df3..ba30a88 100644
--- a/test/H5srcdir_str.h.in
+++ b/test/H5srcdir_str.h.in
@@ -16,5 +16,5 @@
  */
 
 /* Set the 'srcdir' path from configure time */
-static const char *config_srcdir = "@srcdir@";
+#define config_srcdir "@srcdir@"
 
diff --git a/test/Makefile.am b/test/Makefile.am
index 57080aa..d66200d 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
+libh5test_la_SOURCES=h5test.c testframe.c cache_common.c swmr_common.c external_common.c H5srcdir.c
 
 # Use libhd5test.la to compile all of the tests
 LDADD=libh5test.la $(LIBHDF5)
@@ -145,6 +145,12 @@ 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 1a726fa..e59dc3e 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 = NULL;
+    H5C_t * cache_ptr;
     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 24962bc..740523e 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];
+    int32_t local_max_index[NUMBER_OF_ENTRY_TYPES] = {0};
 
     if ( verbose )
         HDfprintf(stdout, "%s: entering.\n", FUNC);
diff --git a/test/cache_tagging.c b/test/cache_tagging.c
index 7ce4e88..c3921ea 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;       /* Root Group Tag */
+    haddr_t root_tag = HADDR_UNDEF;       /* 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 ada7a6f..ce85d1b 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            */
-    char *basename="attr";      /* Name prefix for attribute    */
+    const 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 eaa469f..aa84833 100644
--- a/test/dsets.c
+++ b/test/dsets.c
@@ -7065,16 +7065,15 @@ static void
 make_random_offset_and_increment(long nelts, long *offsetp, long *incp)
 {
     long inc;
-
-    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);
 
+    HDassert(0 < nelts);
+
+    *offsetp = HDrandom() % 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 7e1adf5..8d04770 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;
+        double x = 0.;
         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;
+        float x = 0.;
         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;
+    float x = 0.;
     HDmemcpy(&x, val, sizeof(float));
     retval = (x!=x);
     } else if (FLT_DOUBLE==type) {
-    double x;
+    double x = 0.;
     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;
+    long double x = 0.;
     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;
+        float x = 0.;
 
         HDmemcpy(&x, val, sizeof(float));
         HDsnprintf(s, sizeof(s), "%g", (double)x);
     } else if (FLT_DOUBLE==type) {
-        double x;
+        double x = 0.;
 
         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;
+        long double x = 0.;
 
         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;
+                float x = 0.;
                 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;
+                double x = 0.;
                 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;
+                long double x = 0.;
                 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;
+            float x = 0.;
             HDmemcpy(&x, &saved[j*src_size], sizeof(float));
             HDprintf(" %29.20e\n", (double)x);
         } else if (FLT_DOUBLE==src_type) {
-            double x;
+            double x = 0.;
             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;
+            long double x = 0.;
             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;
+            float x = 0.;
             HDmemcpy(&x, &buf[j*dst_size], sizeof(float));
             HDprintf(" %29.20e\n", (double)x);
         } else if (FLT_DOUBLE==dst_type) {
-            double x;
+            double x = 0.;
             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;
+            long double x = 0.;
             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 47cd53a..5c20e14 100644
--- a/test/fillval.c
+++ b/test/fillval.c
@@ -758,7 +758,8 @@ test_rdwr_cases(hid_t file, hid_t dcpl, const char *dname, void *_fillval,
     int        fillval=(-1), val_rd, should_be;
     int        i, j, *buf=NULL, odd;
     unsigned    u;
-    comp_datatype       rd_c, fill_c, should_be_c;
+    comp_datatype       rd_c, fill_c = {.a = 0, .x = 0, .y = 0, .z = 0},
+                        should_be_c;
     comp_datatype    *buf_c=NULL;
     H5D_space_status_t  allocation;
 
diff --git a/test/null_vol_connector.c b/test/null_vol_connector.c
index 5ed8545..64f62c4 100644
--- a/test/null_vol_connector.c
+++ b/test/null_vol_connector.c
@@ -116,6 +116,12 @@ 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 721a7c6..fdb3179 100644
--- a/test/objcopy_ref.c
+++ b/test/objcopy_ref.c
@@ -1587,7 +1587,6 @@ 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();
@@ -1620,11 +1619,6 @@ 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;
@@ -1646,7 +1640,6 @@ 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:");
@@ -1678,7 +1671,6 @@ 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 6adc6c5..a969b16 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 = %lld\n", symbol->name, (long long)start);
+        HDfprintf(stderr, "Symbol = '%s', location = %ju,%ju\n", symbol->name, (uintmax_t)start[0], (uintmax_t)start[1]);
 
     /* 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 = %lld, record->rec_id = %llu\n", symbol->name, (long long)start, (unsigned long long)record->rec_id);
+        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);
         return -1;
     } /* end if */
 
diff --git a/test/tid.c b/test/tid.c
index d0ae3e4..7a839d2 100644
--- a/test/tid.c
+++ b/test/tid.c
@@ -19,6 +19,13 @@
 #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)
 {
@@ -69,7 +76,7 @@ static int basic_id_test(void)
         goto out;
 
     /* Register a type */
-    myType = H5Iregister_type((size_t)64, 0, (H5I_free_t) free );
+    myType = H5Iregister_type((size_t)64, 0, free_wrapper);
 
     CHECK(myType, H5I_BADID, "H5Iregister_type");
     if(myType == H5I_BADID)
@@ -163,7 +170,7 @@ 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, (H5I_free_t) free );
+    myType = H5Iregister_type((size_t)64, 0, free_wrapper);
 
     CHECK(myType, H5I_BADID, "H5Iregister_type");
     if(myType == H5I_BADID)
@@ -238,7 +245,7 @@ out:
 
 
     /* A dummy search function for the next test */
-static int test_search_func(void H5_ATTR_UNUSED * ptr1, void H5_ATTR_UNUSED * ptr2) { return 0; }
+static int test_search_func(void H5_ATTR_UNUSED * ptr1, hid_t H5_ATTR_UNUSED id, void H5_ATTR_UNUSED * ptr2) { return 0; }
 
     /* Ensure that public functions cannot access "predefined" ID types */
 static int id_predefined_test(void )
@@ -264,7 +271,7 @@ static int id_predefined_test(void )
         goto out;
 
     H5E_BEGIN_TRY
-        testPtr = H5Isearch(H5I_GENPROP_LST, (H5I_search_func_t) test_search_func, testObj);
+        testPtr = H5Isearch(H5I_GENPROP_LST, test_search_func, testObj);
     H5E_END_TRY
 
     CHECK_PTR_NULL(testPtr, "H5Isearch");
@@ -492,7 +499,7 @@ static int test_id_type_list(void)
     H5I_type_t testType;
     int i;    /* Just a counter variable */
 
-    startType = H5Iregister_type((size_t)8, 0, (H5I_free_t) free );
+    startType = H5Iregister_type((size_t)8, 0, free_wrapper);
     CHECK(startType, H5I_BADID, "H5Iregister_type");
     if(startType == H5I_BADID)
         goto out;
@@ -507,7 +514,7 @@ 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, (H5I_free_t) free );
+        currentType = H5Iregister_type((size_t)8, 0, free_wrapper);
         CHECK(currentType, H5I_BADID, "H5Iregister_type");
         if(currentType == H5I_BADID)
             goto out;
@@ -516,7 +523,7 @@ 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, (H5I_free_t) free );
+        currentType = H5Iregister_type((size_t)8, 0, free_wrapper);
         CHECK(currentType, H5I_BADID, "H5Iregister_type");
         if(currentType == H5I_BADID)
             goto out;
@@ -524,7 +531,7 @@ 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, (H5I_free_t) free );
+        testType = H5Iregister_type((size_t)8, 0, free_wrapper);
     H5E_END_TRY
 
     VERIFY(testType, H5I_BADID, "H5Iregister_type");
@@ -533,7 +540,7 @@ 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, (H5I_free_t) free );
+    testType = H5Iregister_type((size_t)8, 0, free_wrapper);
 
     VERIFY(testType, H5I_NTYPES, "H5Iregister_type");
     if(testType != H5I_NTYPES)
diff --git a/test/trefer.c b/test/trefer.c
index 7d87ea9..4ffc2dc 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   *tu32;       /* Temporary pointer to uint32 data */
-    int         i;          /* Counters                         */
+    unsigned 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           */
@@ -101,12 +101,13 @@ test_reference_params(void)
     MESSAGE(5, ("Testing Reference Parameters\n"));
 
     /* Allocate write & read buffers */
-    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);
+    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);
 
-    for(tu32 = (unsigned *)wbuf, i = 0; i < SPACE1_DIM1; i++)
-        *tu32++ = (unsigned)i * 3;
+    for(i = 0; i < SPACE1_DIM1; i++)
+        obuf[i] = i * 3;
 
     /* Create file */
     fid1 = H5Fcreate(FILE_REF_PARAM, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
@@ -137,7 +138,7 @@ 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, wbuf);
+    ret = H5Dwrite(dataset, H5T_NATIVE_UINT, H5S_ALL, H5S_ALL, H5P_DEFAULT, obuf);
     CHECK(ret, FAIL, "H5Dwrite");
 
     /* Close Dataset */
@@ -153,7 +154,7 @@ test_reference_params(void)
     CHECK(attr, H5I_INVALID_HID, "H5Acreate2");
 
     /* Write attribute to disk */
-    ret = H5Awrite(attr, H5T_NATIVE_UINT, wbuf);
+    ret = H5Awrite(attr, H5T_NATIVE_UINT, obuf);
     CHECK(ret, FAIL, "H5Awrite");
 
     /* Close attribute */
@@ -233,19 +234,19 @@ test_reference_params(void)
     VERIFY(type, H5R_BADTYPE, "H5Rget_type ref");
 
     /* Test parameters to H5Requal */
-    ret = H5Requal(NULL, (const H5R_ref_t *)&rbuf[0]);
+    ret = H5Requal(NULL, &rbuf[0]);
     VERIFY(ret, FAIL, "H5Requal ref1");
-    ret = H5Requal((const H5R_ref_t *)&rbuf[0], NULL);
+    ret = H5Requal(&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((const H5R_ref_t *)&rbuf[0], NULL);
+    ret = H5Rcopy(&rbuf[0], NULL);
     VERIFY(ret, FAIL, "H5Rcopy dest_ref");
 
     /* Test parameters to H5Ropen_object */
-    dset2 = H5Ropen_object((const H5R_ref_t *)&rbuf[0], H5I_INVALID_HID, H5I_INVALID_HID);
+    dset2 = H5Ropen_object(&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");
@@ -298,6 +299,7 @@ test_reference_params(void)
     HDfree(wbuf);
     HDfree(rbuf);
     HDfree(tbuf);
+    HDfree(obuf);
 }   /* test_reference_params() */
 
 /****************************************************************
@@ -318,10 +320,9 @@ 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            */
-               *tbuf;       /* temp. buffer read from disk      */
-    unsigned   *tu32;       /* Temporary pointer to uint32 data */
-    int         i, j;       /* Counters                         */
+               *rbuf;       /* buffer read from disk            */
+    unsigned    *ibuf, *obuf;
+    unsigned         i, j;       /* Counters                         */
     H5O_type_t  obj_type;   /* Object type                      */
     herr_t      ret;        /* Generic return value             */
 
@@ -329,12 +330,13 @@ test_reference_obj(void)
     MESSAGE(5, ("Testing Object Reference Functions\n"));
 
     /* Allocate write & read buffers */
-    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);
+    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);
 
-    for(tu32 = (unsigned *)wbuf, i = 0; i < SPACE1_DIM1; i++)
-        *tu32++ = (unsigned)i * 3;
+    for (i = 0; i < SPACE1_DIM1; i++)
+        obuf[i] = i * 3;
 
     /* Create file */
     fid1 = H5Fcreate(FILE_REF_OBJ, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
@@ -357,7 +359,7 @@ 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, wbuf);
+    ret = H5Dwrite(dataset, H5T_NATIVE_UINT, H5S_ALL, H5S_ALL, H5P_DEFAULT, obuf);
     CHECK(ret, FAIL, "H5Dwrite");
 
     /* Close Dataset */
@@ -405,28 +407,28 @@ 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((const H5R_ref_t *)&wbuf[0], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3(&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((const H5R_ref_t *)&wbuf[1], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3(&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((const H5R_ref_t *)&wbuf[2], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3(&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((const H5R_ref_t *)&wbuf[3], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3(&wbuf[3], H5P_DEFAULT, &obj_type);
     CHECK(ret, FAIL, "H5Rget_obj_type3");
     VERIFY(obj_type, H5O_TYPE_NAMED_DATATYPE, "H5Rget_obj_type3");
 
@@ -459,7 +461,7 @@ test_reference_obj(void)
     CHECK(ret, FAIL, "H5Dread");
 
     /* Open dataset object */
-    dset2 = H5Ropen_object((const H5R_ref_t *)&rbuf[0], H5P_DEFAULT, dapl_id);
+    dset2 = H5Ropen_object(&rbuf[0], H5P_DEFAULT, dapl_id);
     CHECK(dset2, H5I_INVALID_HID, "H5Ropen_object");
 
     /* Check information in referenced dataset */
@@ -470,18 +472,18 @@ 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, tbuf);
+    ret = H5Dread(dset2, H5T_NATIVE_UINT, H5S_ALL, H5S_ALL, H5P_DEFAULT, ibuf);
     CHECK(ret, FAIL, "H5Dread");
 
-    for(tu32 = (unsigned *)tbuf, i = 0; i < SPACE1_DIM1; i++, tu32++)
-        VERIFY(*tu32, (uint32_t)(i*3), "Data");
+    for(i = 0; i < SPACE1_DIM1; i++)
+        VERIFY(ibuf[i], 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((const H5R_ref_t *)&rbuf[2], H5P_DEFAULT, H5P_DEFAULT);
+    group = H5Ropen_object(&rbuf[2], H5P_DEFAULT, H5P_DEFAULT);
     CHECK(group, H5I_INVALID_HID, "H5Ropen_object");
 
     /* Close group */
@@ -489,7 +491,7 @@ 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((const H5R_ref_t *)&rbuf[3], H5P_DEFAULT, H5P_DEFAULT);
+    tid1 = H5Ropen_object(&rbuf[3], H5P_DEFAULT, H5P_DEFAULT);
     CHECK(tid1, H5I_INVALID_HID, "H5Ropen_object");
 
     /* Verify correct datatype */
@@ -530,7 +532,8 @@ test_reference_obj(void)
     /* Free memory buffers */
     HDfree(wbuf);
     HDfree(rbuf);
-    HDfree(tbuf);
+    HDfree(ibuf);
+    HDfree(obuf);
 }   /* test_reference_obj() */
 
 /****************************************************************
@@ -565,7 +568,7 @@ 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 */
@@ -583,8 +586,8 @@ 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 = (H5R_ref_t *)HDcalloc(sizeof(H5R_ref_t), SPACE1_DIM1);
-    rbuf = (H5R_ref_t *)HDcalloc(sizeof(H5R_ref_t), SPACE1_DIM1);
+    wbuf = HDcalloc(sizeof(H5R_ref_t), SPACE1_DIM1);
+    rbuf = 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));
 
@@ -647,7 +650,7 @@ 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((const H5R_ref_t *)&wbuf[0], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3(&wbuf[0], H5P_DEFAULT, &obj_type);
     CHECK(ret, FAIL, "H5Rget_obj_type3");
     VERIFY(obj_type, H5O_TYPE_DATASET, "H5Rget_obj_type3");
 
@@ -691,7 +694,7 @@ 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((const H5R_ref_t *)&wbuf[2], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3(&wbuf[2], H5P_DEFAULT, &obj_type);
     CHECK(ret, FAIL, "H5Rget_obj_type3");
     VERIFY(obj_type, H5O_TYPE_DATASET, "H5Rget_obj_type3");
 
@@ -764,7 +767,7 @@ 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((const H5R_ref_t *)&rdata_NA[0], H5P_DEFAULT, H5P_DEFAULT);
+      dset2 = H5Ropen_object(&rdata_NA[0], H5P_DEFAULT, H5P_DEFAULT);
     } H5E_END_TRY;
     VERIFY(dset2, H5I_INVALID_HID, "H5Ropen_object");
 
@@ -798,11 +801,11 @@ test_reference_region(H5F_libver_t libver_low, H5F_libver_t libver_high)
         CHECK(ret, FAIL, "H5Dread");
 
         /* Try to open objects */
-        dset2 = H5Ropen_object((const H5R_ref_t *)&rbuf[0], H5P_DEFAULT, dapl_id);
+        dset2 = H5Ropen_object(&rbuf[0], H5P_DEFAULT, dapl_id);
         CHECK(dset2, H5I_INVALID_HID, "H5Ropen_object");
 
         /* Check what H5Rget_obj_type3 function returns */
-        ret = H5Rget_obj_type3((const H5R_ref_t *)&rbuf[0], H5P_DEFAULT, &obj_type);
+        ret = H5Rget_obj_type3(&rbuf[0], H5P_DEFAULT, &obj_type);
         CHECK(ret, FAIL, "H5Rget_obj_type3");
         VERIFY(obj_type, H5O_TYPE_DATASET, "H5Rget_obj_type3");
 
@@ -821,7 +824,7 @@ 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((const H5R_ref_t *)&rbuf[0], H5P_DEFAULT, H5P_DEFAULT);
+        sid2 = H5Ropen_region(&rbuf[0], H5P_DEFAULT, H5P_DEFAULT);
         CHECK(sid2, H5I_INVALID_HID, "H5Ropen_region");
 
         /* Verify correct hyperslab selected */
@@ -849,7 +852,7 @@ test_reference_region(H5F_libver_t libver_low, H5F_libver_t libver_high)
         CHECK(ret, FAIL, "H5Sclose");
 
         /* Get the element selection */
-        sid2 = H5Ropen_region((const H5R_ref_t *)&rbuf[1], H5P_DEFAULT, H5P_DEFAULT);
+        sid2 = H5Ropen_region(&rbuf[1], H5P_DEFAULT, H5P_DEFAULT);
         CHECK(sid2, H5I_INVALID_HID, "H5Ropen_region");
 
         /* Verify correct elements selected */
@@ -893,7 +896,7 @@ test_reference_region(H5F_libver_t libver_low, H5F_libver_t libver_high)
         CHECK(ret, FAIL, "H5Sclose");
 
         /* Get the unlimited selection */
-        sid2 = H5Ropen_region((const H5R_ref_t *)&rbuf[2], H5P_DEFAULT, H5P_DEFAULT);
+        sid2 = H5Ropen_region(&rbuf[2], H5P_DEFAULT, H5P_DEFAULT);
         CHECK(sid2, H5I_INVALID_HID, "H5Ropen_region");
 
         /* Verify correct hyperslab selected */
@@ -928,7 +931,7 @@ 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((const H5R_ref_t *)&nvrbuf[j], H5P_DEFAULT, &obj_type);
+                ret = H5Rget_obj_type3(&nvrbuf[j], H5P_DEFAULT, &obj_type);
             } H5E_END_TRY;
             VERIFY(ret, FAIL, "H5Rget_obj_type3");
         } /* end for */
@@ -1006,8 +1009,8 @@ 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 = (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);
+    wbuf = HDcalloc(sizeof(H5R_ref_t), (size_t)SPACE1_DIM1);
+    rbuf = 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);
 
@@ -1070,7 +1073,7 @@ 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((const H5R_ref_t *)&wbuf[0], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3(&wbuf[0], H5P_DEFAULT, &obj_type);
     CHECK(ret, FAIL, "H5Rget_obj_type3");
     VERIFY(obj_type, H5O_TYPE_DATASET, "H5Rget_obj_type3");
 
@@ -1128,11 +1131,11 @@ 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((const H5R_ref_t *)&rbuf[0], H5P_DEFAULT, dapl_id);
+    dset3 = H5Ropen_object(&rbuf[0], H5P_DEFAULT, dapl_id);
     CHECK(dset3, H5I_INVALID_HID, "H5Ropen_object");
 
     /* Check what H5Rget_obj_type3 function returns */
-    ret = H5Rget_obj_type3((const H5R_ref_t *)&rbuf[0], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3(&rbuf[0], H5P_DEFAULT, &obj_type);
     CHECK(ret, FAIL, "H5Rget_obj_type3");
     VERIFY(obj_type, H5O_TYPE_DATASET, "H5Rget_obj_type3");
 
@@ -1151,7 +1154,7 @@ 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((const H5R_ref_t *)&rbuf[0], H5P_DEFAULT, H5P_DEFAULT);
+    sid3 = H5Ropen_region(&rbuf[0], H5P_DEFAULT, H5P_DEFAULT);
     CHECK(sid3, H5I_INVALID_HID, "H5Ropen_region");
 
     /* Verify correct hyperslab selected */
@@ -1203,7 +1206,7 @@ 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((const H5R_ref_t *)&rbuf[1], H5P_DEFAULT, H5P_DEFAULT);
+    sid3 = H5Ropen_region(&rbuf[1], H5P_DEFAULT, H5P_DEFAULT);
     CHECK(sid3, H5I_INVALID_HID, "H5Ropen_region");
 
     /* Verify correct elements selected */
@@ -1313,7 +1316,7 @@ test_reference_obj_deleted(void)
     /* Create reference to dataset */
     ret = H5Rcreate_object(fid1, "/Dataset1", &oref);
     CHECK(ret, FAIL, "H5Rcreate_object");
-    ret = H5Rget_obj_type3((const H5R_ref_t *)&oref, H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3(&oref, H5P_DEFAULT, &obj_type);
     CHECK(ret, FAIL, "H5Rget_obj_type3");
     VERIFY(obj_type, H5O_TYPE_DATASET, "H5Rget_obj_type3");
 
@@ -1354,7 +1357,7 @@ test_reference_obj_deleted(void)
     CHECK(ret, FAIL, "H5Dread");
 
     /* Open deleted dataset object */
-    dset2 = H5Ropen_object((const H5R_ref_t *)&oref, H5P_DEFAULT, H5P_DEFAULT);
+    dset2 = H5Ropen_object(&oref, H5P_DEFAULT, H5P_DEFAULT);
     VERIFY(dset2, H5I_INVALID_HID, "H5Ropen_object");
 
     /* Close Dataset */
@@ -1501,7 +1504,7 @@ test_reference_group(void)
     CHECK(ret, FAIL, "H5Dread");
 
     /* Dereference to get the group */
-    gid = H5Ropen_object((const H5R_ref_t *)&rref, H5P_DEFAULT, H5P_DEFAULT);
+    gid = H5Ropen_object(&rref, H5P_DEFAULT, H5P_DEFAULT);
     CHECK(gid, H5I_INVALID_HID, "H5Ropen_object");
 
     /* Iterate through objects in dereferenced group */
@@ -1562,8 +1565,7 @@ 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    *tu32;      /* Temporary pointer to uint32 data */
-    int         i;          /* Local index variables */
+    unsigned    i;          /* Local index variables */
     H5O_type_t  obj_type;   /* Object type */
     herr_t      ret;        /* Generic return value */
 
@@ -1590,8 +1592,8 @@ test_reference_attr(void)
     attr = H5Acreate2(group, "Attr2", H5T_NATIVE_UINT, sid, H5P_DEFAULT, H5P_DEFAULT);
     CHECK(attr, H5I_INVALID_HID, "H5Acreate2");
 
-    for(tu32 = (unsigned *)wbuf, i = 0; i < SPACE1_DIM1; i++)
-        *tu32++ = (unsigned)((i * 3) + 1);
+    for(i = 0; i < SPACE1_DIM1; i++)
+        wbuf[i] = (i * 3) + 1;
 
     /* Write attribute to disk */
     ret = H5Awrite(attr, H5T_NATIVE_UINT, wbuf);
@@ -1609,8 +1611,8 @@ test_reference_attr(void)
     attr = H5Acreate2(dataset, "Attr1", H5T_NATIVE_UINT, sid, H5P_DEFAULT, H5P_DEFAULT);
     CHECK(attr, H5I_INVALID_HID, "H5Acreate2");
 
-    for(tu32 = (unsigned *)wbuf, i = 0; i < SPACE1_DIM1; i++)
-        *tu32++ = (unsigned)(i * 3);
+    for(i = 0; i < SPACE1_DIM1; i++)
+        wbuf[i] = i * 3;
 
     /* Write attribute to disk */
     ret = H5Awrite(attr, H5T_NATIVE_UINT, wbuf);
@@ -1654,8 +1656,8 @@ test_reference_attr(void)
     attr = H5Acreate2(tid, "Attr3", H5T_NATIVE_UINT, sid, H5P_DEFAULT, H5P_DEFAULT);
     CHECK(attr, H5I_INVALID_HID, "H5Acreate2");
 
-    for(tu32 = (unsigned *)wbuf, i = 0; i < SPACE1_DIM1; i++)
-        *tu32++ = (unsigned)((i * 3) + 2);
+    for(i = 0; i < SPACE1_DIM1; i++)
+        wbuf[i] = (i * 3) + 2;
 
     /* Write attribute to disk */
     ret = H5Awrite(attr, H5T_NATIVE_UINT, wbuf);
@@ -1680,28 +1682,28 @@ 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((const H5R_ref_t *)&ref_wbuf[0], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3(&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((const H5R_ref_t *)&ref_wbuf[1], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3(&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((const H5R_ref_t *)&ref_wbuf[2], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3(&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((const H5R_ref_t *)&ref_wbuf[3], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3(&ref_wbuf[3], H5P_DEFAULT, &obj_type);
     CHECK(ret, FAIL, "H5Rget_obj_type3");
     VERIFY(obj_type, H5O_TYPE_NAMED_DATATYPE, "H5Rget_obj_type3");
 
@@ -1734,7 +1736,7 @@ test_reference_attr(void)
     CHECK(ret, FAIL, "H5Dread");
 
     /* Open attribute on dataset object */
-    attr = H5Ropen_attr((const H5R_ref_t *)&ref_rbuf[0], H5P_DEFAULT, H5P_DEFAULT);
+    attr = H5Ropen_attr(&ref_rbuf[0], H5P_DEFAULT, H5P_DEFAULT);
     CHECK(attr, H5I_INVALID_HID, "H5Ropen_attr");
 
     /* Check information in referenced dataset */
@@ -1748,38 +1750,38 @@ test_reference_attr(void)
     ret = H5Aread(attr, H5T_NATIVE_UINT, rbuf);
     CHECK(ret, FAIL, "H5Aread");
 
-    for(tu32 = (unsigned *)rbuf, i = 0; i < SPACE1_DIM1; i++, tu32++)
-        VERIFY(*tu32, (uint32_t)(i * 3), "Data");
+    for(i = 0; i < SPACE1_DIM1; i++)
+        VERIFY(rbuf[i], i * 3, "Data");
 
     /* Close dereferenced Dataset */
     ret = H5Aclose(attr);
     CHECK(ret, FAIL, "H5Aclose");
 
     /* Open attribute on group object */
-    attr = H5Ropen_attr((const H5R_ref_t *)&ref_rbuf[2], H5P_DEFAULT, H5P_DEFAULT);
+    attr = H5Ropen_attr(&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(tu32 = (unsigned *)rbuf, i = 0; i < SPACE1_DIM1; i++, tu32++)
-        VERIFY(*tu32, (uint32_t)((i * 3) + 1), "Data");
+    for(i = 0; i < SPACE1_DIM1; i++)
+        VERIFY(rbuf[i], (i * 3) + 1, "Data");
 
     /* Close attribute  */
     ret = H5Aclose(attr);
     CHECK(ret, FAIL, "H5Aclose");
 
     /* Open attribute on named datatype object */
-    attr = H5Ropen_attr((const H5R_ref_t *)&ref_rbuf[3], H5P_DEFAULT, H5P_DEFAULT);
+    attr = H5Ropen_attr(&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(tu32 = (unsigned *)rbuf, i = 0; i < SPACE1_DIM1; i++, tu32++)
-        VERIFY(*tu32, (uint32_t)((i * 3) + 2), "Data");
+    for(i = 0; i < SPACE1_DIM1; i++)
+        VERIFY(rbuf[i], (i * 3) + 2, "Data");
 
     /* Close attribute  */
     ret = H5Aclose(attr);
@@ -1826,8 +1828,7 @@ 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    *tu32;      /* Temporary pointer to uint32 data */
-    int         i;          /* Local index variables */
+    unsigned    i;          /* Local index variables */
     H5O_type_t  obj_type;   /* Object type */
     herr_t      ret;        /* Generic return value */
 
@@ -1854,8 +1855,8 @@ test_reference_external(void)
     attr = H5Acreate2(group, "Attr2", H5T_NATIVE_UINT, sid, H5P_DEFAULT, H5P_DEFAULT);
     CHECK(attr, H5I_INVALID_HID, "H5Acreate2");
 
-    for(tu32 = (unsigned *)wbuf, i = 0; i < SPACE1_DIM1; i++)
-        *tu32++ = (unsigned)((i * 3) + 1);
+    for(i = 0; i < SPACE1_DIM1; i++)
+        wbuf[i] = (i * 3) + 1;
 
     /* Write attribute to disk */
     ret = H5Awrite(attr, H5T_NATIVE_UINT, wbuf);
@@ -1873,8 +1874,8 @@ test_reference_external(void)
     attr = H5Acreate2(dataset, "Attr1", H5T_NATIVE_UINT, sid, H5P_DEFAULT, H5P_DEFAULT);
     CHECK(attr, H5I_INVALID_HID, "H5Acreate2");
 
-    for(tu32 = (unsigned *)wbuf, i = 0; i < SPACE1_DIM1; i++)
-        *tu32++ = (unsigned)(i * 3);
+    for(i = 0; i < SPACE1_DIM1; i++)
+        wbuf[i] = i * 3;
 
     /* Write attribute to disk */
     ret = H5Awrite(attr, H5T_NATIVE_UINT, wbuf);
@@ -1918,8 +1919,8 @@ test_reference_external(void)
     attr = H5Acreate2(tid, "Attr3", H5T_NATIVE_UINT, sid, H5P_DEFAULT, H5P_DEFAULT);
     CHECK(attr, H5I_INVALID_HID, "H5Acreate2");
 
-    for(tu32 = (unsigned *)wbuf, i = 0; i < SPACE1_DIM1; i++)
-        *tu32++ = (unsigned)((i * 3) + 2);
+    for(i = 0; i < SPACE1_DIM1; i++)
+        wbuf[i] = (i * 3) + 2;
 
     /* Write attribute to disk */
     ret = H5Awrite(attr, H5T_NATIVE_UINT, wbuf);
@@ -1940,28 +1941,28 @@ 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((const H5R_ref_t *)&ref_wbuf[0], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3(&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((const H5R_ref_t *)&ref_wbuf[1], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3(&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((const H5R_ref_t *)&ref_wbuf[2], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3(&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((const H5R_ref_t *)&ref_wbuf[3], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3(&ref_wbuf[3], H5P_DEFAULT, &obj_type);
     CHECK(ret, FAIL, "H5Rget_obj_type3");
     VERIFY(obj_type, H5O_TYPE_NAMED_DATATYPE, "H5Rget_obj_type3");
 
@@ -2014,7 +2015,7 @@ test_reference_external(void)
     CHECK(ret, FAIL, "H5Dread");
 
     /* Open attribute on dataset object */
-    attr = H5Ropen_attr((const H5R_ref_t *)&ref_rbuf[0], H5P_DEFAULT, H5P_DEFAULT);
+    attr = H5Ropen_attr(&ref_rbuf[0], H5P_DEFAULT, H5P_DEFAULT);
     CHECK(attr, H5I_INVALID_HID, "H5Ropen_attr");
 
     /* Check information in referenced dataset */
@@ -2028,38 +2029,38 @@ test_reference_external(void)
     ret = H5Aread(attr, H5T_NATIVE_UINT, rbuf);
     CHECK(ret, FAIL, "H5Aread");
 
-    for(tu32 = (unsigned *)rbuf, i = 0; i < SPACE1_DIM1; i++, tu32++)
-        VERIFY(*tu32, (uint32_t)(i * 3), "Data");
+    for(i = 0; i < SPACE1_DIM1; i++)
+        VERIFY(rbuf[i], i * 3, "Data");
 
     /* Close dereferenced Dataset */
     ret = H5Aclose(attr);
     CHECK(ret, FAIL, "H5Aclose");
 
     /* Open attribute on group object */
-    attr = H5Ropen_attr((const H5R_ref_t *)&ref_rbuf[2], H5P_DEFAULT, H5P_DEFAULT);
+    attr = H5Ropen_attr(&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(tu32 = (unsigned *)rbuf, i = 0; i < SPACE1_DIM1; i++, tu32++)
-        VERIFY(*tu32, (uint32_t)((i * 3) + 1), "Data");
+    for(i = 0; i < SPACE1_DIM1; i++)
+        VERIFY(rbuf[i], (i * 3) + 1, "Data");
 
     /* Close attribute  */
     ret = H5Aclose(attr);
     CHECK(ret, FAIL, "H5Aclose");
 
     /* Open attribute on named datatype object */
-    attr = H5Ropen_attr((const H5R_ref_t *)&ref_rbuf[3], H5P_DEFAULT, H5P_DEFAULT);
+    attr = H5Ropen_attr(&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(tu32 = (unsigned *)rbuf, i = 0; i < SPACE1_DIM1; i++, tu32++)
-        VERIFY(*tu32, (uint32_t)((i * 3) + 2), "Data");
+    for(i = 0; i < SPACE1_DIM1; i++)
+        VERIFY(rbuf[i], (i * 3) + 2, "Data");
 
     /* Close attribute  */
     ret = H5Aclose(attr);
@@ -2121,9 +2122,9 @@ test_reference_compat_conv(void)
 
     /* Allocate write & read buffers */
     wbuf_obj = (hobj_ref_t *)HDcalloc(sizeof(hobj_ref_t), SPACE1_DIM1);
-    rbuf_obj = (H5R_ref_t *)HDcalloc(sizeof(H5R_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 = (H5R_ref_t *)HDcalloc(sizeof(H5R_ref_t), 2);
+    rbuf_reg = HDcalloc(sizeof(H5R_ref_t), 2);
 
     /* Create file */
     fid1 = H5Fcreate(FILE_REF_COMPAT, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
@@ -2286,43 +2287,43 @@ test_reference_compat_conv(void)
     CHECK(ret, FAIL, "H5Dread");
 
     /* Verify type of objects pointed at */
-    ret = H5Rget_obj_type3((const H5R_ref_t *)&rbuf_obj[0], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3(&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((const H5R_ref_t *)&rbuf_obj[1], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3(&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((const H5R_ref_t *)&rbuf_obj[2], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3(&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((const H5R_ref_t *)&rbuf_obj[3], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3(&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((const H5R_ref_t *)&rbuf_obj[0], H5P_DEFAULT, H5P_DEFAULT);
+    dset2 = H5Ropen_object(&rbuf_obj[0], H5P_DEFAULT, H5P_DEFAULT);
     CHECK(dset2, H5I_INVALID_HID, "H5Ropen_object");
 
     ret = H5Dclose(dset2);
     CHECK(ret, FAIL, "H5Dclose");
 
-    dset2 = H5Ropen_object((const H5R_ref_t *)&rbuf_obj[1], H5P_DEFAULT, H5P_DEFAULT);
+    dset2 = H5Ropen_object(&rbuf_obj[1], H5P_DEFAULT, H5P_DEFAULT);
     CHECK(dset2, H5I_INVALID_HID, "H5Ropen_object");
 
     ret = H5Dclose(dset2);
     CHECK(ret, FAIL, "H5Dclose");
 
-    group2 = H5Ropen_object((const H5R_ref_t *)&rbuf_obj[2], H5P_DEFAULT, H5P_DEFAULT);
+    group2 = H5Ropen_object(&rbuf_obj[2], H5P_DEFAULT, H5P_DEFAULT);
     CHECK(group2, H5I_INVALID_HID, "H5Ropen_object");
 
     ret = H5Gclose(group2);
     CHECK(ret, FAIL, "H5Gclose");
 
-    tid2 = H5Ropen_object((const H5R_ref_t *)&rbuf_obj[3], H5P_DEFAULT, H5P_DEFAULT);
+    tid2 = H5Ropen_object(&rbuf_obj[3], H5P_DEFAULT, H5P_DEFAULT);
     CHECK(tid2, H5I_INVALID_HID, "H5Ropen_object");
 
     ret = H5Tclose(tid2);
@@ -2342,22 +2343,22 @@ test_reference_compat_conv(void)
     CHECK(ret, FAIL, "H5Dread");
 
     /* Verify type of objects pointed at */
-    ret = H5Rget_obj_type3((const H5R_ref_t *)&rbuf_reg[0], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3(&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((const H5R_ref_t *)&rbuf_reg[1], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3(&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((const H5R_ref_t *)&rbuf_reg[0], H5P_DEFAULT, H5P_DEFAULT);
+    dset2 = H5Ropen_object(&rbuf_reg[0], H5P_DEFAULT, H5P_DEFAULT);
     CHECK(dset2, H5I_INVALID_HID, "H5Ropen_object");
 
     ret = H5Dclose(dset2);
     CHECK(ret, FAIL, "H5Dclose");
 
-    dset2 = H5Ropen_object((const H5R_ref_t *)&rbuf_reg[1], H5P_DEFAULT, H5P_DEFAULT);
+    dset2 = H5Ropen_object(&rbuf_reg[1], H5P_DEFAULT, H5P_DEFAULT);
     CHECK(dset2, H5I_INVALID_HID, "H5Ropen_object");
 
     ret = H5Dclose(dset2);
@@ -2414,8 +2415,8 @@ test_reference_perf(void)
                *rbuf_deprec;/* deprecated references            */
     hdset_reg_ref_t *wbuf_reg_deprec,   /* deprecated references*/
                *rbuf_reg_deprec;        /* deprecated references*/
-    unsigned   *tu32;       /* Temporary pointer to uint32 data */
-    int         i, j;       /* Counters                         */
+    unsigned *ibuf, *obuf;
+    unsigned i, j;       /* Counters                         */
     H5O_type_t  obj_type;   /* Object type                      */
     herr_t      ret;        /* Generic return value             */
     double      t1, t2, t;  /* Timers                           */
@@ -2424,18 +2425,20 @@ test_reference_perf(void)
     MESSAGE(5, ("Testing Object Reference Performance\n"));
 
     /* Allocate write & read buffers */
-    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;
+    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;
 
     /* Create file */
     fid1 = H5Fcreate(FILE_REF_OBJ, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
@@ -2458,7 +2461,7 @@ 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, wbuf);
+    ret = H5Dwrite(dataset, H5T_NATIVE_UINT, H5S_ALL, H5S_ALL, H5P_DEFAULT, obuf);
     CHECK(ret, FAIL, "H5Dwrite");
 
     /* Close Dataset */
@@ -2518,7 +2521,7 @@ 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((const H5R_ref_t *)&wbuf[0], H5P_DEFAULT, &obj_type);
+    ret = H5Rget_obj_type3(&wbuf[0], H5P_DEFAULT, &obj_type);
     CHECK(ret, FAIL, "H5Rget_obj_type3");
     VERIFY(obj_type, H5O_TYPE_DATASET, "H5Rget_obj_type3");
 
@@ -2670,7 +2673,7 @@ test_reference_perf(void)
     CHECK(ret, FAIL, "H5Dread");
 
     /* Open dataset object */
-    dset2 = H5Ropen_object((const H5R_ref_t *)&rbuf[0], H5P_DEFAULT, dapl_id);
+    dset2 = H5Ropen_object(&rbuf[0], H5P_DEFAULT, dapl_id);
     CHECK(dset2, H5I_INVALID_HID, "H5Ropen_object");
 
     /* Check information in referenced dataset */
@@ -2681,11 +2684,11 @@ 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, tbuf);
+    ret = H5Dread(dset2, H5T_NATIVE_UINT, H5S_ALL, H5S_ALL, H5P_DEFAULT, ibuf);
     CHECK(ret, FAIL, "H5Dread");
 
-    for(tu32 = (unsigned *)tbuf, i = 0; i < (int)dims1[0]; i++, tu32++)
-        VERIFY(*tu32, (uint32_t)(i*3), "Data");
+    for(i = 0; i < dims1[0]; i++)
+        VERIFY(ibuf[i], i * 3, "Data");
 
     /* Close dereferenced Dataset */
     ret = H5Dclose(dset2);
@@ -2767,7 +2770,7 @@ test_reference_perf(void)
     CHECK(ret, FAIL, "H5Fclose");
 
     /* Destroy references */
-    for(j = 0; j < (int)dims1[0]; j++) {
+    for(j = 0; j < dims1[0]; j++) {
         ret = H5Rdestroy(&wbuf[j]);
         CHECK(ret, FAIL, "H5Rdestroy");
         ret = H5Rdestroy(&wbuf_reg[j]);
@@ -2788,6 +2791,8 @@ 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 949f41b..1b77e9c 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 731270c..cc01084 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};
-    char *val[SPACE1_DIM1] = {"But", "reuniting", "is a", "great joy"};
+    const char *val[SPACE1_DIM1] = {"But", "reuniting", "is a", "great joy"};
     hsize_t marray[] = {NUMP};
     hsize_t coord[SPACE1_RANK][NUMP];
     herr_t ret;
 
-    char *wdata[SPACE1_DIM1] = {"Parting", "is such a", "sweet", "sorrow."};
+    const 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 eb2dcf4..18d6b35 100644
--- a/test/vds_swmr.h
+++ b/test/vds_swmr.h
@@ -84,31 +84,17 @@
 #define N_PLANES_TO_WRITE   25
 
 /* Planes */
-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}
-};
+extern hsize_t PLANES[N_SOURCES][RANK];
 
 /* File names for source datasets */
-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"}
-};
+extern char FILE_NAMES[N_SOURCES][NAME_LEN];
 
 /* VDS file name */
-static char VDS_FILE_NAME[NAME_LEN] = "vds_swmr.h5";
+extern char VDS_FILE_NAME[NAME_LEN];
 
 /* Dataset names */
-static char SOURCE_DSET_PATH[NAME_LEN] = "/source_dset";
-static char VDS_DSET_NAME[NAME_LEN]    = "vds_dset";
+extern char SOURCE_DSET_PATH[NAME_LEN];
+extern char VDS_DSET_NAME[NAME_LEN];
 
 /* Fill values */
 #endif /* VDS_SWMR_H */
diff --git a/test/vds_swmr_common.c b/test/vds_swmr_common.c
new file mode 100644
index 0000000..d2b4bd6
--- /dev/null
+++ b/test/vds_swmr_common.c
@@ -0,0 +1,36 @@
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+ * 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 c2153e5..1b4bc56 100644
--- a/tools/lib/h5diff.c
+++ b/tools/lib/h5diff.c
@@ -258,6 +258,8 @@ 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)
@@ -374,6 +376,7 @@ 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 2a45913..55ad65c 100644
--- a/tools/lib/h5diff_array.c
+++ b/tools/lib/h5diff_array.c
@@ -2245,6 +2245,9 @@ 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)
 {
@@ -2305,6 +2308,7 @@ 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 47ce690..6fc9de4 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)
+                           void       *fapl_t_ptr H5_ATTR_UNUSED)
 {
     int ret_value = 1;
 
diff --git a/tools/src/h5import/h5import.c b/tools/src/h5import/h5import.c
index 1eef5ab..65c2359 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 ((*((uint8_t*)(&ibyte))) == 0x67) {
+    if ((*((volatile 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 c628beb..16899a3 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, rc = 1;
+    int i;
     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 opt;
+    int bound, opt;
     int ret_value = 0;
 
     /* parse command line options */
@@ -492,19 +492,21 @@ int parse_command_line(int argc, const char **argv, pack_opt_t* options)
                 break;
 
             case 'j':
-                options->low_bound = (H5F_libver_t)HDatoi(opt_arg);
-                if (options->low_bound < H5F_LIBVER_EARLIEST || options->low_bound > H5F_LIBVER_LATEST) {
+                bound = HDatoi(opt_arg);
+                if (bound < H5F_LIBVER_EARLIEST || bound > H5F_LIBVER_LATEST) {
                     error_msg("in parsing low bound\n");
                     goto done;
                 }
+                options->low_bound = bound;
                 break;
 
             case 'k':
-                options->high_bound = (H5F_libver_t)HDatoi(opt_arg);
-                if (options->high_bound < H5F_LIBVER_EARLIEST || options->high_bound > H5F_LIBVER_LATEST) {
+                bound = HDatoi(opt_arg);
+                if (bound < H5F_LIBVER_EARLIEST || 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 aaac285..87ca31c 100644
--- a/tools/test/h5repack/h5repackgentest.c
+++ b/tools/test/h5repack/h5repackgentest.c
@@ -314,7 +314,6 @@ 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;