Merge pull request #2325 in HDFFV/hdf5 from ~DYOUNG/werror:h5t_copy to develop

Merged per discussion with Elena.

* commit '3f903a441ad84001ea66589728bd8b036b6fdfca':
  Take out the temporary performance tests.
  Make calls through a function pointer.  Use the same number of arguments, always.
  Increase iterations, provide a baseline for no-op, simplify the overhead case a bit.
  Temporarily add some code that measures the time to run the simplest possible H5T__copy_all()-like routine 10 million times and then measures the version with FUNC_ENTER_STATIC/_LEAVE_NOAPI and a HGOTO_ERROR() statement.
  H5T_copy() constification plus Quincey's contributions.

15 files changed, 480 insertions, 194 deletions

diff --git a/src/H5Aint.c b/src/H5Aint.c
index fc5ea34..1a74abe 100644
--- a/src/H5Aint.c
+++ b/src/H5Aint.c
@@ -224,7 +224,7 @@ H5A__create(const H5G_loc_t *loc, const char *attr_name, const H5T_t *type,
         HGOTO_ERROR(H5E_DATASET, H5E_CANTSET, NULL, "can't set version of dataspace")
 
     /* Copy the object header information */
-    if(H5O_loc_copy(&(attr->oloc), loc->oloc, H5_COPY_DEEP) < 0)
+    if(H5O_loc_copy_deep(&(attr->oloc), loc->oloc) < 0)
         HGOTO_ERROR(H5E_ATTR, H5E_CANTOPENOBJ, NULL, "unable to copy entry")
 
     /* Deep copy of the group hierarchy path */
@@ -390,7 +390,7 @@ H5A__open_common(const H5G_loc_t *loc, H5A_t *attr)
         HGOTO_ERROR(H5E_ATTR, H5E_CANTRELEASE, FAIL, "can't release group hier. path")
 
     /* Deep copy of the symbol table entry */
-    if(H5O_loc_copy(&(attr->oloc), loc->oloc, H5_COPY_DEEP) < 0)
+    if(H5O_loc_copy_deep(&(attr->oloc), loc->oloc) < 0)
         HGOTO_ERROR(H5E_ATTR, H5E_CANTOPENOBJ, FAIL, "unable to copy entry")
 
     /* Deep copy of the group hier. path */
@@ -909,7 +909,7 @@ H5A__get_type(H5A_t *attr)
      * reopen the type before returning it to the user. Make the type
      * read-only.
      */
-    if (NULL == (dt = H5T_copy(attr->shared->dt, H5T_COPY_REOPEN)))
+    if (NULL == (dt = H5T_copy_reopen(attr->shared->dt)))
         HGOTO_ERROR(H5E_ATTR, H5E_CANTINIT, H5I_INVALID_HID, "unable to copy datatype")
 
     /* Mark any datatypes as being in memory now */
diff --git a/src/H5Dint.c b/src/H5Dint.c
index 0d67fd0..1624f7b 100644
--- a/src/H5Dint.c
+++ b/src/H5Dint.c
@@ -1534,7 +1534,7 @@ H5D_open(const H5G_loc_t *loc, hid_t dapl_id)
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
 
     /* Shallow copy (take ownership) of the object location object */
-    if(H5O_loc_copy(&(dataset->oloc), loc->oloc, H5_COPY_SHALLOW) < 0)
+    if(H5O_loc_copy_shallow(&(dataset->oloc), loc->oloc) < 0)
         HGOTO_ERROR(H5E_DATASET, H5E_CANTCOPY, NULL, "can't copy object location")
 
     /* Shallow copy (take ownership) of the group hier. path */
@@ -3881,7 +3881,7 @@ H5D__get_type(const H5D_t *dset)
         HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to patch datatype's file pointer")
 
     /* Copy the dataset's datatype */
-    if(NULL == (dt = H5T_copy(dset->shared->type, H5T_COPY_REOPEN)))
+    if(NULL == (dt = H5T_copy_reopen(dset->shared->type)))
         HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to copy datatype")
 
     /* Mark any datatypes as being in memory now */
diff --git a/src/H5Fmount.c b/src/H5Fmount.c
index 13d95aa..5e6b899 100644
--- a/src/H5Fmount.c
+++ b/src/H5Fmount.c
@@ -766,7 +766,7 @@ H5F_traverse_mount(H5O_loc_t *oloc/*in,out*/)
                 HGOTO_ERROR(H5E_FILE, H5E_CANTFREE, FAIL, "unable to free object location")
 
             /* Copy the entry for the root group */
-            if(H5O_loc_copy(oloc, mnt_oloc, H5_COPY_DEEP) < 0)
+            if(H5O_loc_copy_deep(oloc, mnt_oloc) < 0)
                 HGOTO_ERROR(H5E_FILE, H5E_CANTCOPY, FAIL, "unable to copy object location")
 
             /* In case the shared root group info points to a different file handle
diff --git a/src/H5Gint.c b/src/H5Gint.c
index e0b8bd7..a3849a6 100644
--- a/src/H5Gint.c
+++ b/src/H5Gint.c
@@ -336,7 +336,7 @@ H5G_open(const H5G_loc_t *loc)
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "can't allocate space for group")
 
     /* Shallow copy (take ownership) of the group location object */
-    if(H5O_loc_copy(&(grp->oloc), loc->oloc, H5_COPY_SHALLOW) < 0)
+    if(H5O_loc_copy_shallow(&(grp->oloc), loc->oloc) < 0)
         HGOTO_ERROR(H5E_SYM, H5E_CANTCOPY, NULL, "can't copy object location")
     if(H5G_name_copy(&(grp->path), loc->path, H5_COPY_SHALLOW) < 0)
         HGOTO_ERROR(H5E_SYM, H5E_CANTCOPY, NULL, "can't copy path")
diff --git a/src/H5Gobj.c b/src/H5Gobj.c
index 15dbd79..1892182 100644
--- a/src/H5Gobj.c
+++ b/src/H5Gobj.c
@@ -738,7 +738,7 @@ H5G__obj_info(const H5O_loc_t *oloc, H5G_info_t *grp_info)
     H5G_loc_reset(&grp_loc);
 
     /* Deep copy (duplicate) of the group location object */
-    if(H5O_loc_copy(&grp_oloc, (H5O_loc_t *)oloc, H5_COPY_DEEP) < 0)    /* (Casting away const OK - QAK) */
+    if(H5O_loc_copy_deep(&grp_oloc, oloc) < 0)
         HGOTO_ERROR(H5E_SYM, H5E_CANTCOPY, FAIL, "can't copy object location")
 
     /* Open the group */
diff --git a/src/H5Gtraverse.c b/src/H5Gtraverse.c
index 7482e27..0f27880 100644
--- a/src/H5Gtraverse.c
+++ b/src/H5Gtraverse.c
@@ -132,7 +132,7 @@ H5G__traverse_slink_cb(H5G_loc_t H5_ATTR_UNUSED *grp_loc, const char H5_ATTR_UNU
     } /* end if */
     else {
         /* Copy new location information for resolved object */
-        H5O_loc_copy(udata->obj_loc->oloc, obj_loc->oloc, H5_COPY_DEEP);
+        H5O_loc_copy_deep(udata->obj_loc->oloc, obj_loc->oloc);
 
         /* Indicate that the object exists */
         udata->exists = TRUE;
diff --git a/src/H5L.c b/src/H5L.c
index 0d5bc02..47e29c0 100644
--- a/src/H5L.c
+++ b/src/H5L.c
@@ -1910,7 +1910,7 @@ H5L__link_cb(H5G_loc_t *grp_loc/*in*/, const char *name, const H5O_link_t H5_ATT
              * copy and wipe out grp_loc)
              */
             H5G_name_reset(&temp_path);
-            if(H5O_loc_copy(&temp_oloc, grp_loc->oloc, H5_COPY_DEEP) < 0)
+            if(H5O_loc_copy_deep(&temp_oloc, grp_loc->oloc) < 0)
                 HGOTO_ERROR(H5E_LINK, H5E_CANTCOPY, FAIL, "unable to copy object location")
 
             temp_loc.oloc = &temp_oloc;
@@ -2695,7 +2695,7 @@ H5L__move_dest_cb(H5G_loc_t *grp_loc/*in*/, const char *name,
              * copy and wipe out grp_loc)
              */
             H5G_name_reset(&temp_path);
-            if(H5O_loc_copy(&temp_oloc, grp_loc->oloc, H5_COPY_DEEP) < 0)
+            if(H5O_loc_copy_deep(&temp_oloc, grp_loc->oloc) < 0)
                 HGOTO_ERROR(H5E_LINK, H5E_CANTCOPY, FAIL, "unable to copy object location")
 
             temp_loc.oloc = &temp_oloc;
diff --git a/src/H5Oint.c b/src/H5Oint.c
index d5a3a71..04220af 100644
--- a/src/H5Oint.c
+++ b/src/H5Oint.c
@@ -1913,27 +1913,19 @@ H5O_loc_reset(H5O_loc_t *loc)
     FUNC_LEAVE_NOAPI(SUCCEED)
 } /* end H5O_loc_reset() */
 
-
+
 /*-------------------------------------------------------------------------
  * Function:    H5O_loc_copy
  *
- * Purpose:     Copy object location information
+ * Purpose:     Copy object location information, according to the depth.
  *
  * Return:    Success:    Non-negative
- *        Failure:    Negative
+ *            Failure:    Negative
  *
  * Programmer:    Quincey Koziol
  *              koziol@ncsa.uiuc.edu
  *              Monday, September 19, 2005
  *
- * Notes:       'depth' parameter determines how much of the group entry
- *              structure we want to copy.  The values are:
- *                  H5_COPY_SHALLOW - Copy all the field values from the source
- *                      to the destination, but not copying objects pointed to.
- *                      (Destination "takes ownership" of objects pointed to)
- *                  H5_COPY_DEEP - Copy all the fields from the source to
- *                      the destination, deep copying objects pointed to.
- *
  *-------------------------------------------------------------------------
  */
 herr_t
@@ -1946,25 +1938,88 @@ H5O_loc_copy(H5O_loc_t *dst, H5O_loc_t *src, H5_copy_depth_t depth)
     HDassert(dst);
     HDassert(depth == H5_COPY_SHALLOW || depth == H5_COPY_DEEP);
 
+    /* Invoke correct routine */
+    if(depth == H5_COPY_SHALLOW)
+        H5O_loc_copy_shallow(dst, src);
+    else
+        H5O_loc_copy_deep(dst, src);
+
+    FUNC_LEAVE_NOAPI(SUCCEED)
+} /* end H5O_loc_copy() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5O_loc_copy_shallow
+ *
+ * Purpose:     Shallow copy object location information.  Copies all the field
+ *              values from the source to the destination, but not copying
+ *              objects pointed to.  (i.e. destination "takes ownership" of
+ *              objects pointed to)
+ *
+ * Return:    Success:    Non-negative
+ *            Failure:    Negative
+ *
+ * Programmer:	Quincey Koziol
+ *	        January 18, 2020
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5O_loc_copy_shallow(H5O_loc_t *dst, H5O_loc_t *src)
+{
+    FUNC_ENTER_NOAPI_NOINIT_NOERR
+
+    /* Check arguments */
+    HDassert(src);
+    HDassert(dst);
+
     /* Copy the top level information */
     H5MM_memcpy(dst, src, sizeof(H5O_loc_t));
 
-    /* Deep copy the names */
-    if(depth == H5_COPY_DEEP) {
-        /* If the original entry was holding open the file, this one should
-         * hold it open, too.
-         */
-        if(src->holding_file)
-            H5F_INCR_NOPEN_OBJS(dst->file);
-    }
-    else if(depth == H5_COPY_SHALLOW) {
-        H5O_loc_reset(src);
-    }
+    /* Reset the source location, as the destination 'owns' it now */
+    H5O_loc_reset(src);
 
     FUNC_LEAVE_NOAPI(SUCCEED)
-} /* end H5O_loc_copy() */
+} /* end H5O_loc_copy_shallow() */
 
+
+/*-------------------------------------------------------------------------
+ * Function:    H5O_loc_copy_deep
+ *
+ * Purpose:     Deep copy object location information.  Copies all the fields
+ *              from the source to the destination, deep copying objects
+ *              pointed to.
+ *
+ * Return:    Success:    Non-negative
+ *            Failure:    Negative
+ *
+ * Programmer:	David Young
+ *	        January 18, 2020
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5O_loc_copy_deep(H5O_loc_t *dst, const H5O_loc_t *src)
+{
+    FUNC_ENTER_NOAPI_NOINIT_NOERR
+
+    /* Check arguments */
+    HDassert(src);
+    HDassert(dst);
+
+    /* Copy the top level information */
+    H5MM_memcpy(dst, src, sizeof(H5O_loc_t));
+
+    /* If the original entry was holding open the file, this one should
+     * hold it open, too.
+     */
+    if(src->holding_file)
+        H5F_INCR_NOPEN_OBJS(dst->file);
+
+    FUNC_LEAVE_NOAPI(SUCCEED)
+} /* end H5O_loc_copy_deep() */
 
+
 /*-------------------------------------------------------------------------
  * Function:    H5O_loc_hold_file
  *
diff --git a/src/H5Oprivate.h b/src/H5Oprivate.h
index 52a72b2..ceaa96d 100644
--- a/src/H5Oprivate.h
+++ b/src/H5Oprivate.h
@@ -997,6 +997,8 @@ H5_DLL herr_t H5O_debug(H5F_t *f, haddr_t addr, FILE * stream, int indent,
 /* These functions operate on object locations */
 H5_DLL herr_t H5O_loc_reset(H5O_loc_t *loc);
 H5_DLL herr_t H5O_loc_copy(H5O_loc_t *dst, H5O_loc_t *src, H5_copy_depth_t depth);
+H5_DLL herr_t H5O_loc_copy_shallow(H5O_loc_t *dst, H5O_loc_t *src);
+H5_DLL herr_t H5O_loc_copy_deep(H5O_loc_t *dst, const H5O_loc_t *src);
 H5_DLL herr_t H5O_loc_hold_file(H5O_loc_t *loc);
 H5_DLL herr_t H5O_loc_free(H5O_loc_t *loc);
 H5_DLL H5O_loc_t *H5O_get_loc(hid_t id);
diff --git a/src/H5T.c b/src/H5T.c
index f1c2dbb..5d3c4a1 100644
--- a/src/H5T.c
+++ b/src/H5T.c
@@ -301,6 +301,9 @@
 /* Local Typedefs */
 /******************/
 
+/* Typedef for recursive const-correct datatype copying routines */
+typedef H5T_t *(*H5T_copy_func_t)(H5T_t *old_dt);
+
 
 /********************/
 /* Local Prototypes */
@@ -313,6 +316,11 @@ static herr_t H5T__set_size(H5T_t *dt, size_t size);
 static herr_t H5T__close_cb(H5T_t *dt);
 static H5T_path_t *H5T__path_find_real(const H5T_t *src, const H5T_t *dst, const char *name, H5T_conv_func_t *conv);
 static hbool_t H5T__detect_vlen_ref(const H5T_t *dt);
+static H5T_t *H5T__initiate_copy(const H5T_t *old_dt);
+static H5T_t *H5T__copy_transient(H5T_t *old_dt);
+static H5T_t *H5T__copy_all(H5T_t *old_dt);
+static herr_t H5T__complete_copy(H5T_t *new_dt, const H5T_t *old_dt,
+    H5T_shared_t *reopened_fo, hbool_t set_memory_type, H5T_copy_func_t copyfn);
 
 
 /*****************************/
@@ -3304,132 +3312,152 @@ done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5T__create() */
 
-
+
 /*-------------------------------------------------------------------------
- * Function:  H5T_copy
+ * Function:  H5T__initiate_copy
  *
- * Purpose:   Copies datatype OLD_DT.     The resulting data type is not
- *            locked and is a transient type.
+ * Purpose:   Allocates datatype structures, copies core fields, and initializes
+ *            VOL fields.
  *
  * Return:    Success:    Pointer to a new copy of the OLD_DT argument.
- *
  *            Failure:    NULL
  *
- * Programmer:    Robb Matzke
- *        Thursday, December  4, 1997
+ * Note:      Common code for both H5T_copy and H5T_copy_reopen, as part of
+ *            the const-correct datatype copying routines.
+ *
+ * Programmer:	David Young
+ *	        January 18, 2020
  *
  *-------------------------------------------------------------------------
  */
-H5T_t *
-H5T_copy(H5T_t *old_dt, H5T_copy_t method)
+static H5T_t *
+H5T__initiate_copy(const H5T_t *old_dt)
 {
-    H5T_t           *new_dt = NULL, *tmp = NULL;
-    H5T_shared_t    *reopened_fo = NULL;
-    unsigned        i;
-    char            *s;
-    H5T_t           *ret_value = NULL;    /* Return value */
-
-    FUNC_ENTER_NOAPI(NULL)
+    H5T_t *new_dt = NULL;       /* Copy of datatype */
+    H5T_t *ret_value = NULL;    /* Return value */
 
-    /* check args */
-    HDassert(old_dt);
+    FUNC_ENTER_STATIC
 
     /* Allocate space */
     if(NULL == (new_dt = H5FL_MALLOC(H5T_t)))
-        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
+        HGOTO_ERROR(H5E_DATATYPE, H5E_CANTALLOC, NULL, "H5T_t memory allocation failed")
     if(NULL == (new_dt->shared = H5FL_MALLOC(H5T_shared_t)))
-        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
+        HGOTO_ERROR(H5E_DATATYPE, H5E_CANTALLOC, NULL, "H5T_shared_t memory allocation failed")
 
-    /* Copy shared information (entry information is copied last) */
+    /* Copy shared information */
     *(new_dt->shared) = *(old_dt->shared);
 
-    /* No VOL object */
+    /* Reset VOL fields */
     new_dt->vol_obj = NULL;
-
-    /* No owned VOL object */
     new_dt->shared->owned_vol_obj = NULL;
 
-    /* Check what sort of copy we are making */
-    switch (method) {
-        case H5T_COPY_TRANSIENT:
-            /*
-             * Return an unlocked transient type.
-             */
-            new_dt->shared->state = H5T_STATE_TRANSIENT;
-            break;
+    /* Set return value */
+    ret_value = new_dt;
 
-        case H5T_COPY_ALL:
-            /*
-             * Return a transient type (locked or unlocked) or an unopened named
-             * type.  Immutable transient types are degraded to read-only.
-             */
-            if(H5T_STATE_OPEN==old_dt->shared->state)
-                new_dt->shared->state = H5T_STATE_NAMED;
-            else if(H5T_STATE_IMMUTABLE==old_dt->shared->state)
-                new_dt->shared->state = H5T_STATE_RDONLY;
-            break;
+done:
+    if(ret_value == NULL)
+        if(new_dt) {
+            if(new_dt->shared)
+                new_dt->shared = H5FL_FREE(H5T_shared_t, new_dt->shared);
+            new_dt = H5FL_FREE(H5T_t, new_dt);
+        } /* end if */
 
-        case H5T_COPY_REOPEN:
-            /*
-             * Return a transient type (locked or unlocked) or an opened named
-             * type.  Immutable transient types are degraded to read-only.
-             */
-            if(old_dt->sh_loc.type == H5O_SHARE_TYPE_COMMITTED) {
-                /* Check if the object is already open */
-                if(NULL == (reopened_fo = (H5T_shared_t *)H5FO_opened(old_dt->sh_loc.file, old_dt->sh_loc.u.loc.oh_addr))) {
-                    /* Clear any errors from H5FO_opened() */
-                    H5E_clear_stack(NULL);
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5T__initiate_copy() */
 
-                    /* Open named datatype again */
-                    if(H5O_open(&old_dt->oloc) < 0)
-                        HGOTO_ERROR(H5E_DATATYPE, H5E_CANTOPENOBJ, NULL, "unable to reopen named data type")
+
+/*-------------------------------------------------------------------------
+ * Function:  H5T__copy_transient
+ *
+ * Purpose:   Part of recursive framework for const-correct datatype copying.
+ *
+ * Return:    Success:    Pointer to a new copy of the OLD_DT argument.
+ *            Failure:    NULL
+ *
+ * Programmer:	David Young
+ *	        January 18, 2020
+ *
+ *-------------------------------------------------------------------------
+ */
+static H5T_t *
+H5T__copy_transient(H5T_t *old_dt)
+{
+    H5T_t *ret_value = NULL;            /* Return value */
 
-                    /* Insert opened named datatype into opened object list for the file */
-                    if(H5FO_insert(old_dt->sh_loc.file, old_dt->sh_loc.u.loc.oh_addr, new_dt->shared, FALSE)<0)
-                        HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINSERT, NULL, "can't insert datatype into list of open objects")
+    FUNC_ENTER_STATIC
 
-                    /* Increment object count for the object in the top file */
-                    if(H5FO_top_incr(old_dt->sh_loc.file, old_dt->sh_loc.u.loc.oh_addr) < 0)
-                        HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINC, NULL, "can't increment object count")
+    /* Copy datatype, with correct method */
+    if(NULL == (ret_value = H5T_copy(old_dt, H5T_COPY_TRANSIENT)))
+        HGOTO_ERROR(H5E_DATATYPE, H5E_CANTCOPY, NULL, "can't make 'transient' copy of datatype")
 
-                    new_dt->shared->fo_count = 1;
-                } /* end if */
-                else {
-                    /* The object is already open.  Free the H5T_shared_t struct
-                     * we had been using and use the one that already exists.
-                     * Not terribly efficient. */
-                    new_dt->shared = H5FL_FREE(H5T_shared_t, new_dt->shared);
-                    new_dt->shared = reopened_fo;
-
-                    reopened_fo->fo_count++;
-
-                    /* Check if the object has been opened through the top file yet */
-                    if(H5FO_top_count(old_dt->sh_loc.file, old_dt->sh_loc.u.loc.oh_addr) == 0) {
-                        /* Open the object through this top file */
-                        if(H5O_open(&old_dt->oloc) < 0)
-                            HGOTO_ERROR(H5E_DATATYPE, H5E_CANTOPENOBJ, NULL, "unable to open object header")
-                    } /* end if */
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5T__copy_transient() */
 
-                    /* Increment object count for the object in the top file */
-                    if(H5FO_top_incr(old_dt->sh_loc.file, old_dt->sh_loc.u.loc.oh_addr) < 0)
-                        HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINC, NULL, "can't increment object count")
-                } /* end else */
-                new_dt->shared->state = H5T_STATE_OPEN;
-            }
-            else if(H5T_STATE_IMMUTABLE == old_dt->shared->state) {
-                new_dt->shared->state = H5T_STATE_RDONLY;
-            }
-            break;
-        default:
-            HGOTO_ERROR(H5E_DATATYPE, H5E_BADTYPE, NULL, "invalid copy method type")
-    } /* end switch */
+
+/*-------------------------------------------------------------------------
+ * Function:  H5T__copy_all
+ *
+ * Purpose:   Part of recursive framework for const-correct datatype copying.
+ *
+ * Return:    Success:    Pointer to a new copy of the OLD_DT argument.
+ *            Failure:    NULL
+ *
+ * Programmer:	David Young
+ *	        January 18, 2020
+ *
+ *-------------------------------------------------------------------------
+ */
+static H5T_t *
+H5T__copy_all(H5T_t *old_dt)
+{
+    H5T_t *ret_value = NULL;            /* Return value */
+
+    FUNC_ENTER_STATIC
+
+    /* Copy datatype, with correct method */
+    if(NULL == (ret_value = H5T_copy(old_dt, H5T_COPY_ALL)))
+        HGOTO_ERROR(H5E_DATATYPE, H5E_CANTCOPY, NULL, "can't make 'all' copy of datatype")
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5T__copy_transient() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:  H5T__complete_copy
+ *
+ * Purpose:   Completes copying datatype fields, as part of the recursive
+ *            const-correct datatype copy routines.
+ *
+ * Return:    Success:    non-negative
+ *            Failure:    negative
+ *
+ * Note:      Common code for both H5T_copy and H5T_copy_reopen.
+ *
+ * Programmer:	David Young
+ *	        January 18, 2020
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5T__complete_copy(H5T_t *new_dt, const H5T_t *old_dt, H5T_shared_t *reopened_fo,
+    hbool_t set_memory_type, H5T_copy_func_t copyfn)
+{
+    H5T_t           *tmp = NULL;        /* Temporary copy of compound field's datatype */
+    char            *s;                 /* Temporary copy of compound field name / enum value name */
+    unsigned        i;                  /* Local index variable */
+    herr_t ret_value = SUCCEED;         /* Return value */
+
+    FUNC_ENTER_STATIC
 
     /* Update fields in the new struct, if we aren't sharing an already opened
      * committed datatype */
     if(!reopened_fo) {
         /* Copy parent information */
         if(old_dt->shared->parent)
-            new_dt->shared->parent = H5T_copy(old_dt->shared->parent, method);
+            if(NULL == (new_dt->shared->parent = (*copyfn)(old_dt->shared->parent)))
+                HGOTO_ERROR(H5E_DATATYPE, H5E_CANTCOPY, FAIL, "can't copy datatype's parent type")
 
         switch(new_dt->shared->type) {
             case H5T_COMPOUND:
@@ -3443,10 +3471,8 @@ H5T_copy(H5T_t *old_dt, H5T_copy_t method)
                     */
                     /* Only malloc if space has been allocated for members - NAF */
                     if(new_dt->shared->u.compnd.nalloc > 0) {
-                        new_dt->shared->u.compnd.memb =
-                                (H5T_cmemb_t *)H5MM_malloc(new_dt->shared->u.compnd.nalloc * sizeof(H5T_cmemb_t));
-                        if (NULL == new_dt->shared->u.compnd.memb)
-                            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
+                        if(NULL == (new_dt->shared->u.compnd.memb = H5MM_malloc(new_dt->shared->u.compnd.nalloc * sizeof(H5T_cmemb_t))))
+                            HGOTO_ERROR(H5E_DATATYPE, H5E_CANTALLOC, FAIL, "memory allocation failed")
 
                         H5MM_memcpy(new_dt->shared->u.compnd.memb, old_dt->shared->u.compnd.memb,
                                 new_dt->shared->u.compnd.nmembs * sizeof(H5T_cmemb_t));
@@ -3456,15 +3482,17 @@ H5T_copy(H5T_t *old_dt, H5T_copy_t method)
                         unsigned    j;
                         int         old_match;
 
-                        s = new_dt->shared->u.compnd.memb[i].name;
-                        new_dt->shared->u.compnd.memb[i].name = H5MM_xstrdup(s);
-                        tmp = H5T_copy (old_dt->shared->u.compnd.memb[i].type, method);
+                        if(NULL == (s = H5MM_xstrdup(new_dt->shared->u.compnd.memb[i].name)))
+                            HGOTO_ERROR(H5E_DATATYPE, H5E_CANTCOPY, FAIL, "can't copy string for compound field's name")
+                        new_dt->shared->u.compnd.memb[i].name = s;
+                        if(NULL == (tmp = (*copyfn)(old_dt->shared->u.compnd.memb[i].type)))
+                            HGOTO_ERROR(H5E_DATATYPE, H5E_CANTCOPY, FAIL, "can't copy compound field's datatype")
                         new_dt->shared->u.compnd.memb[i].type = tmp;
                         HDassert(tmp != NULL);
 
                         /* Range check against compound member's offset */
-                        if ((accum_change < 0) && ((ssize_t) new_dt->shared->u.compnd.memb[i].offset < accum_change))
-                            HGOTO_ERROR(H5E_DATATYPE, H5E_BADVALUE, NULL, "invalid field size in datatype")
+                        if((accum_change < 0) && ((ssize_t) new_dt->shared->u.compnd.memb[i].offset < accum_change))
+                            HGOTO_ERROR(H5E_DATATYPE, H5E_BADVALUE, FAIL, "invalid field size in datatype")
 
                         /* Apply the accumulated size change to the offset of the field */
                         new_dt->shared->u.compnd.memb[i].offset += (size_t) accum_change;
@@ -3479,7 +3507,7 @@ H5T_copy(H5T_t *old_dt, H5T_copy_t method)
 
                             /* check if we couldn't find a match */
                             if(old_match < 0)
-                                HGOTO_ERROR(H5E_DATATYPE, H5E_CANTCOPY, NULL, "fields in datatype corrupted")
+                                HGOTO_ERROR(H5E_DATATYPE, H5E_CANTCOPY, FAIL, "fields in datatype corrupted")
                         } /* end if */
                         else
                             old_match = (int) i;
@@ -3494,8 +3522,8 @@ H5T_copy(H5T_t *old_dt, H5T_copy_t method)
                     } /* end for */
 
                     /* Range check against datatype size */
-                    if ((accum_change < 0) && ((ssize_t) new_dt->shared->size < accum_change))
-                        HGOTO_ERROR(H5E_DATATYPE, H5E_BADVALUE, NULL, "invalid field size in datatype")
+                    if((accum_change < 0) && ((ssize_t) new_dt->shared->size < accum_change))
+                        HGOTO_ERROR(H5E_DATATYPE, H5E_BADVALUE, FAIL, "invalid field size in datatype")
 
                     /* Apply the accumulated size change to the size of the compound struct */
                     new_dt->shared->size += (size_t) accum_change;
@@ -3508,27 +3536,25 @@ H5T_copy(H5T_t *old_dt, H5T_copy_t method)
                 * of each new member with copied values. That is, H5T_copy() is a
                 * deep copy.
                 */
-                new_dt->shared->u.enumer.name =
-                        (char **)H5MM_malloc(new_dt->shared->u.enumer.nalloc * sizeof(char*));
-                new_dt->shared->u.enumer.value =
-                        (uint8_t *)H5MM_malloc(new_dt->shared->u.enumer.nalloc * new_dt->shared->size);
-                if(NULL == new_dt->shared->u.enumer.value)
-                    HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
+                if(NULL == (new_dt->shared->u.enumer.name = H5MM_malloc(new_dt->shared->u.enumer.nalloc * sizeof(char*))))
+                    HGOTO_ERROR(H5E_DATATYPE, H5E_CANTALLOC, FAIL, "enam name array memory allocation failed")
+                if(NULL == (new_dt->shared->u.enumer.value = H5MM_malloc(new_dt->shared->u.enumer.nalloc * new_dt->shared->size)))
+                    HGOTO_ERROR(H5E_DATATYPE, H5E_CANTALLOC, FAIL, "enam value array memory allocation failed")
                 H5MM_memcpy(new_dt->shared->u.enumer.value, old_dt->shared->u.enumer.value,
                         new_dt->shared->u.enumer.nmembs * new_dt->shared->size);
                 for(i = 0; i < new_dt->shared->u.enumer.nmembs; i++) {
-                    s = old_dt->shared->u.enumer.name[i];
-                    new_dt->shared->u.enumer.name[i] = H5MM_xstrdup(s);
+                    if(NULL == (s = H5MM_xstrdup(old_dt->shared->u.enumer.name[i])))
+                        HGOTO_ERROR(H5E_DATATYPE, H5E_CANTCOPY, FAIL, "can't copy string for enum value's name")
+                    new_dt->shared->u.enumer.name[i] = s;
                 } /* end for */
                 break;
 
             case H5T_VLEN:
             case H5T_REFERENCE:
-                if(method == H5T_COPY_TRANSIENT || method == H5T_COPY_REOPEN) {
+                if(set_memory_type)
                     /* H5T_copy converts any type into a memory type */
                     if(H5T_set_loc(new_dt, NULL, H5T_LOC_MEMORY) < 0)
-                        HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, NULL, "invalid datatype location")
-                } /* end if */
+                        HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "invalid datatype location")
                 break;
 
             case H5T_OPAQUE:
@@ -3540,7 +3566,7 @@ H5T_copy(H5T_t *old_dt, H5T_copy_t method)
 
             case H5T_ARRAY:
                 /* Re-compute the array's size, in case it's base type changed size */
-                new_dt->shared->size=new_dt->shared->u.array.nelem*new_dt->shared->parent->shared->size;
+                new_dt->shared->size = new_dt->shared->u.array.nelem * new_dt->shared->parent->shared->size;
                 break;
 
             case H5T_NO_CLASS:
@@ -3559,15 +3585,15 @@ H5T_copy(H5T_t *old_dt, H5T_copy_t method)
      * type and the new type is also named.
      */
     if(H5O_loc_reset(&new_dt->oloc) < 0)
-        HGOTO_ERROR(H5E_DATATYPE, H5E_CANTRESET, NULL, "unable to initialize location")
+        HGOTO_ERROR(H5E_DATATYPE, H5E_CANTRESET, FAIL, "unable to initialize location")
     if(H5G_name_reset(&new_dt->path) < 0)
-        HGOTO_ERROR(H5E_DATATYPE, H5E_CANTOPENOBJ, NULL, "unable to reset path")
+        HGOTO_ERROR(H5E_DATATYPE, H5E_CANTOPENOBJ, FAIL, "unable to reset path")
 
     if(new_dt->shared->state == H5T_STATE_NAMED || new_dt->shared->state == H5T_STATE_OPEN) {
-        if(H5O_loc_copy(&(new_dt->oloc), &(old_dt->oloc), H5_COPY_DEEP) < 0)
-            HGOTO_ERROR(H5E_DATATYPE, H5E_CANTCOPY, NULL, "can't copy object location")
+        if(H5O_loc_copy_deep(&(new_dt->oloc), &(old_dt->oloc)) < 0)
+            HGOTO_ERROR(H5E_DATATYPE, H5E_CANTCOPY, FAIL, "can't copy object location")
         if(H5G_name_copy(&(new_dt->path), &(old_dt->path), H5_COPY_DEEP) < 0)
-            HGOTO_ERROR(H5E_DATATYPE, H5E_CANTOPENOBJ, NULL, "unable to copy path")
+            HGOTO_ERROR(H5E_DATATYPE, H5E_CANTOPENOBJ, FAIL, "unable to copy path")
     } /* end if */
 
     /* Copy shared location information if the new type is named or if it is
@@ -3576,28 +3602,194 @@ H5T_copy(H5T_t *old_dt, H5T_copy_t method)
     if((old_dt->sh_loc.type == H5O_SHARE_TYPE_SOHM || old_dt->sh_loc.type == H5O_SHARE_TYPE_HERE) ||
             new_dt->shared->state == H5T_STATE_NAMED || new_dt->shared->state == H5T_STATE_OPEN) {
         if(H5O_set_shared(&(new_dt->sh_loc), &(old_dt->sh_loc)) < 0)
-            HGOTO_ERROR(H5E_DATATYPE, H5E_CANTCOPY, NULL, "can't copy shared information")
+            HGOTO_ERROR(H5E_DATATYPE, H5E_CANTCOPY, FAIL, "can't copy shared information")
     } /* end if */
     else
         /* Reset shared component info */
         H5O_msg_reset_share(H5O_DTYPE_ID, new_dt);
 
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5T__complete_copy() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:  H5T_copy
+ *
+ * Purpose:   Copies datatype OLD_DT.     The resulting data type is not
+ *            locked and is a transient type.
+ *
+ * Return:    Success:    Pointer to a new copy of the OLD_DT argument.
+ *            Failure:    NULL
+ *
+ * Programmer:    Robb Matzke
+ *        Thursday, December  4, 1997
+ *
+ *-------------------------------------------------------------------------
+ */
+H5T_t *
+H5T_copy(const H5T_t *old_dt, H5T_copy_t method)
+{
+    H5T_t *new_dt = NULL;       /* New datatype */
+    H5T_copy_func_t copyfn;     /* Pointer to correct copy routine */
+    H5T_t *ret_value = NULL;    /* Return value */
+
+    FUNC_ENTER_NOAPI(NULL)
+
+    /* check args */
+    HDassert(old_dt);
+
+    /* Allocate and copy core datatype information */
+    if(NULL == (new_dt = H5T__initiate_copy(old_dt)))
+        HGOTO_ERROR(H5E_DATATYPE, H5E_CANTCOPY, NULL, "can't copy core datatype info")
+
+    /* Check what sort of copy we are making */
+    switch (method) {
+        case H5T_COPY_TRANSIENT:
+            /*
+             * Return an unlocked transient type.
+             */
+            new_dt->shared->state = H5T_STATE_TRANSIENT;
+            copyfn = H5T__copy_transient;
+            break;
+
+        case H5T_COPY_ALL:
+            /*
+             * Return a transient type (locked or unlocked) or an unopened named
+             * type.  Immutable transient types are degraded to read-only.
+             */
+            if(H5T_STATE_OPEN==old_dt->shared->state)
+                new_dt->shared->state = H5T_STATE_NAMED;
+            else if(H5T_STATE_IMMUTABLE==old_dt->shared->state)
+                new_dt->shared->state = H5T_STATE_RDONLY;
+            copyfn = H5T__copy_all;
+            break;
+
+        default:
+            HGOTO_ERROR(H5E_DATATYPE, H5E_BADTYPE, NULL, "invalid copy method type")
+    } /* end switch */
+
+    /* Finish making the copy of the datatype */
+    if(H5T__complete_copy(new_dt, old_dt, NULL, (method == H5T_COPY_TRANSIENT), copyfn) < 0)
+        HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, NULL, "can't complete datatype initialization")
+
     /* Set return value */
     ret_value = new_dt;
 
 done:
-    if(ret_value == NULL) {
+    if(ret_value == NULL)
         if(new_dt) {
-            if(new_dt->shared)
-                new_dt->shared = H5FL_FREE(H5T_shared_t, new_dt->shared);
+            HDassert(new_dt->shared);
+            new_dt->shared = H5FL_FREE(H5T_shared_t, new_dt->shared);
             new_dt = H5FL_FREE(H5T_t, new_dt);
         } /* end if */
-    } /* end if */
 
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5T_copy() */
 
+
+/*-------------------------------------------------------------------------
+ * Function:  H5T_copy_reopen
+ *
+ * Purpose:   Copy a datatype, possibly reopening a named datatype, as part
+ *            the const-correct datatype copying routines.
+ *
+ * Return:    Success:    Pointer to a new copy of the OLD_DT argument.
+ *            Failure:    NULL
+ *
+ * Programmer:	David Young
+ *	        January 18, 2020
+ *
+ *-------------------------------------------------------------------------
+ */
+H5T_t *
+H5T_copy_reopen(H5T_t *old_dt)
+{
+    H5T_t           *new_dt = NULL;         /* New datatype */
+    H5T_shared_t    *reopened_fo = NULL;    /* Pointer to reopened existing named datatype */
+    H5T_t           *ret_value = NULL;      /* Return value */
+
+    FUNC_ENTER_NOAPI(NULL)
+
+    /* check args */
+    HDassert(old_dt);
+
+    /* Allocate and copy core datatype information */
+    if(NULL == (new_dt = H5T__initiate_copy(old_dt)))
+        HGOTO_ERROR(H5E_DATATYPE, H5E_CANTCOPY, NULL, "can't copy core datatype info")
+
+    /*
+     * Return a transient type (locked or unlocked) or an opened named
+     * type.  Immutable transient types are degraded to read-only.
+     */
+    if(old_dt->sh_loc.type == H5O_SHARE_TYPE_COMMITTED) {
+        /* Check if the object is already open */
+        if(NULL == (reopened_fo = (H5T_shared_t *)H5FO_opened(old_dt->sh_loc.file, old_dt->sh_loc.u.loc.oh_addr))) {
+            /* Clear any errors from H5FO_opened() */
+            H5E_clear_stack(NULL);
+
+            /* Open named datatype again */
+            if(H5O_open(&old_dt->oloc) < 0)
+                HGOTO_ERROR(H5E_DATATYPE, H5E_CANTOPENOBJ, NULL, "unable to reopen named data type")
+
+            /* Insert opened named datatype into opened object list for the file */
+            if(H5FO_insert(old_dt->sh_loc.file, old_dt->sh_loc.u.loc.oh_addr, new_dt->shared, FALSE)<0)
+                HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINSERT, NULL, "can't insert datatype into list of open objects")
+
+            /* Increment object count for the object in the top file */
+            if(H5FO_top_incr(old_dt->sh_loc.file, old_dt->sh_loc.u.loc.oh_addr) < 0)
+                HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINC, NULL, "can't increment object count")
+
+            new_dt->shared->fo_count = 1;
+        } /* end if */
+        else {
+            /* The object is already open.  Free the H5T_shared_t struct
+             * we had been using and use the one that already exists.
+             * Not terribly efficient. */
+            new_dt->shared = H5FL_FREE(H5T_shared_t, new_dt->shared);
+            new_dt->shared = reopened_fo;
+
+            reopened_fo->fo_count++;
+
+            /* Check if the object has been opened through the top file yet */
+            if(H5FO_top_count(old_dt->sh_loc.file, old_dt->sh_loc.u.loc.oh_addr) == 0) {
+                /* Open the object through this top file */
+                if(H5O_open(&old_dt->oloc) < 0)
+                    HGOTO_ERROR(H5E_DATATYPE, H5E_CANTOPENOBJ, NULL, "unable to open object header")
+            } /* end if */
+
+            /* Increment object count for the object in the top file */
+            if(H5FO_top_incr(old_dt->sh_loc.file, old_dt->sh_loc.u.loc.oh_addr) < 0)
+                HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINC, NULL, "can't increment object count")
+        } /* end else */
+
+        /* Set state for new datatype */
+        new_dt->shared->state = H5T_STATE_OPEN;
+    } /* end if */
+    else
+        /* Downgrade immutable datatypes to read-only */
+        if(H5T_STATE_IMMUTABLE == old_dt->shared->state)
+            new_dt->shared->state = H5T_STATE_RDONLY;
+
+    /* Finish making the copy of the datatype */
+    if(H5T__complete_copy(new_dt, old_dt, reopened_fo, TRUE, H5T_copy_reopen) < 0)
+        HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, NULL, "can't complete datatype initialization")
+
+    /* Set return value */
+    ret_value = new_dt;
+
+done:
+    if(ret_value == NULL)
+        if(new_dt) {
+            HDassert(new_dt->shared);
+            new_dt->shared = H5FL_FREE(H5T_shared_t, new_dt->shared);
+            new_dt = H5FL_FREE(H5T_t, new_dt);
+        } /* end if */
+
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5T_copy_reopen() */
 
+
 /*-------------------------------------------------------------------------
  * Function:  H5T_lock
  *
diff --git a/src/H5Tcommit.c b/src/H5Tcommit.c
index 1b922d5..7d26af3 100644
--- a/src/H5Tcommit.c
+++ b/src/H5Tcommit.c
@@ -446,7 +446,7 @@ H5T__commit(H5F_t *file, H5T_t *type, hid_t tcpl_id)
         HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "unable to update type header message")
 
     /* Copy the new object header's location into the datatype, taking ownership of it */
-    if(H5O_loc_copy(&(type->oloc), &temp_oloc, H5_COPY_SHALLOW) < 0)
+    if(H5O_loc_copy_shallow(&(type->oloc), &temp_oloc) < 0)
         HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "unable to copy datatype location")
     if(H5G_name_copy(&(type->path), &temp_path, H5_COPY_SHALLOW) < 0)
         HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "unable to copy datatype location")
@@ -943,7 +943,7 @@ H5T_open(const H5G_loc_t *loc)
 #endif /* H5_USING_MEMCHECKER */
 
         /* Shallow copy (take ownership) of the object location object */
-        if(H5O_loc_copy(&dt->oloc, loc->oloc, H5_COPY_SHALLOW) < 0)
+        if(H5O_loc_copy_shallow(&dt->oloc, loc->oloc) < 0)
             HGOTO_ERROR(H5E_DATATYPE, H5E_CANTCOPY, NULL, "can't copy object location")
 
         /* Shallow copy (take ownership) of the group hier. path */
@@ -1033,7 +1033,7 @@ H5T__open_oid(const H5G_loc_t *loc)
     dt->shared->state = H5T_STATE_OPEN;
 
     /* Shallow copy (take ownership) of the object location object */
-    if(H5O_loc_copy(&dt->oloc, loc->oloc, H5_COPY_SHALLOW) < 0)
+    if(H5O_loc_copy_shallow(&dt->oloc, loc->oloc) < 0)
         HGOTO_ERROR(H5E_DATATYPE, H5E_CANTCOPY, NULL, "can't copy object location")
 
     /* Shallow copy (take ownership) of the group hier. path */
diff --git a/src/H5Tcompound.c b/src/H5Tcompound.c
index d4f1008..f4a9e04 100644
--- a/src/H5Tcompound.c
+++ b/src/H5Tcompound.c
@@ -51,8 +51,9 @@
 /********************/
 /* Local Prototypes */
 /********************/
-static herr_t H5T_pack(const H5T_t *dt);
-static htri_t H5T_is_packed(const H5T_t *dt);
+static herr_t H5T__pack(const H5T_t *dt);
+static htri_t H5T__is_packed(const H5T_t *dt);
+static H5T_t *H5T__reopen_member_type(const H5T_t *dt, unsigned membno);
 
 
 /*********************/
@@ -226,7 +227,7 @@ H5Tget_member_type(hid_t type_id, unsigned membno)
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, H5I_INVALID_HID, "invalid member number")
 
     /* Retrieve the datatype for the member */
-    if(NULL == (memb_dt = H5T_get_member_type(dt, membno, H5T_COPY_REOPEN)))
+    if(NULL == (memb_dt = H5T__reopen_member_type(dt, membno)))
         HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, H5I_INVALID_HID, "unable to retrieve member type")
 
     /* Get an ID for the datatype */
@@ -245,8 +246,7 @@ done:
 /*-------------------------------------------------------------------------
  * Function:	H5T_get_member_type
  *
- * Purpose:	Private function for H5Tget_member_type.  Returns the data
- *              type of the specified member.
+ * Purpose:	Returns a copy of the data type of the specified member.
  *
  * Return:	Success:	A copy of the member datatype;
  *				modifying the returned datatype does not
@@ -260,18 +260,19 @@ done:
  *-------------------------------------------------------------------------
  */
 H5T_t *
-H5T_get_member_type(const H5T_t *dt, unsigned membno, H5T_copy_t method)
+H5T_get_member_type(const H5T_t *dt, unsigned membno)
 {
     H5T_t	*ret_value = NULL;      /* Return value */
 
     FUNC_ENTER_NOAPI(NULL)
 
+    /* Sanity checks */
     HDassert(dt);
     HDassert(membno < dt->shared->u.compnd.nmembs);
 
-    /* Copy datatype into an atom */
-    if(NULL == (ret_value = H5T_copy(dt->shared->u.compnd.memb[membno].type, method)))
-	HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, NULL, "unable to copy member datatype")
+    /* Copy datatype */
+    if(NULL == (ret_value = H5T_copy(dt->shared->u.compnd.memb[membno].type, H5T_COPY_TRANSIENT)))
+	HGOTO_ERROR(H5E_DATATYPE, H5E_CANTCOPY, NULL, "unable to copy member datatype")
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
@@ -279,6 +280,43 @@ done:
 
 
 /*-------------------------------------------------------------------------
+ * Function:	H5T__reopen_member_type
+ *
+ * Purpose:	Private function for H5Tget_member_type.  Returns a re-opened
+ *              copy of the data type of the specified member.
+ *
+ * Return:	Success:	A copy of the member datatype;
+ *				modifying the returned datatype does not
+ *				modify the member type.
+ *
+ *		Failure:        NULL
+ *
+ * Programmer:	David Young
+ *	        January 18, 2020
+ *
+ *-------------------------------------------------------------------------
+ */
+static H5T_t *
+H5T__reopen_member_type(const H5T_t *dt, unsigned membno)
+{
+    H5T_t	*ret_value = NULL;      /* Return value */
+
+    FUNC_ENTER_STATIC
+
+    /* Sanity checks */
+    HDassert(dt);
+    HDassert(membno < dt->shared->u.compnd.nmembs);
+
+    /* Copy datatype, possibly re-opening it */
+    if(NULL == (ret_value = H5T_copy_reopen(dt->shared->u.compnd.memb[membno].type)))
+	HGOTO_ERROR(H5E_DATATYPE, H5E_CANTCOPY, NULL, "unable to reopen member datatype")
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5T__reopen_member_type() */
+
+
+/*-------------------------------------------------------------------------
  * Function:	H5T__get_member_size
  *
  * Purpose:	Returns the size of the specified member.
@@ -387,7 +425,7 @@ H5Tpack(hid_t type_id)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a compound datatype")
 
     /* Pack */
-    if(H5T_pack(dt) < 0)
+    if(H5T__pack(dt) < 0)
 	HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "unable to pack compound datatype")
 
 done:
@@ -493,7 +531,7 @@ done:
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5T_pack
+ * Function:	H5T__pack
  *
  * Purpose:	Recursively packs a compound datatype by removing padding
  *		bytes. This is done in place (that is, destructively).
@@ -506,17 +544,17 @@ done:
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5T_pack(const H5T_t *dt)
+H5T__pack(const H5T_t *dt)
 {
     herr_t      ret_value = SUCCEED;    /* Return value */
 
-    FUNC_ENTER_NOAPI_NOINIT
+    FUNC_ENTER_STATIC
 
     HDassert(dt);
 
     if(H5T_detect_class(dt, H5T_COMPOUND, FALSE) > 0) {
         /* If datatype has been packed, skip packing it and indicate success */
-        if(TRUE == H5T_is_packed(dt))
+        if(TRUE == H5T__is_packed(dt))
             HGOTO_DONE(SUCCEED)
 
         /* Check for packing unmodifiable datatype */
@@ -524,7 +562,7 @@ H5T_pack(const H5T_t *dt)
             HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "datatype is read-only")
 
         if(dt->shared->parent) {
-            if (H5T_pack(dt->shared->parent) < 0)
+            if(H5T__pack(dt->shared->parent) < 0)
                 HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "unable to pack parent of datatype")
 
             /* Adjust size of datatype appropriately */
@@ -539,7 +577,7 @@ H5T_pack(const H5T_t *dt)
 
             /* Recursively pack the members */
             for(i = 0; i < dt->shared->u.compnd.nmembs; i++) {
-                if(H5T_pack(dt->shared->u.compnd.memb[i].type) < 0)
+                if(H5T__pack(dt->shared->u.compnd.memb[i].type) < 0)
                     HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "unable to pack part of a compound datatype")
 
                 /* Update the member size */
@@ -552,7 +590,7 @@ H5T_pack(const H5T_t *dt)
             for(i = 0, offset = 0; i < dt->shared->u.compnd.nmembs; i++) {
                 dt->shared->u.compnd.memb[i].offset = offset;
                 offset += dt->shared->u.compnd.memb[i].size;
-            }
+            } /* end for */
 
             /* Change total size */
             dt->shared->size = MAX(1, offset);
@@ -564,11 +602,11 @@ H5T_pack(const H5T_t *dt)
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5T_pack() */
+} /* end H5T__pack() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5T_is_packed
+ * Function:	H5T__is_packed
  *
  * Purpose:	Checks whether a datatype which is compound (or has compound
  *              components) is packed.
@@ -583,11 +621,11 @@ done:
  *-------------------------------------------------------------------------
  */
 static htri_t
-H5T_is_packed(const H5T_t *dt)
+H5T__is_packed(const H5T_t *dt)
 {
     htri_t      ret_value = TRUE;       /* Return value */
 
-    FUNC_ENTER_NOAPI_NOINIT_NOERR
+    FUNC_ENTER_STATIC_NOERR
 
     HDassert(dt);
 
@@ -596,12 +634,11 @@ H5T_is_packed(const H5T_t *dt)
         dt = dt->shared->parent;
 
     /* If this is a compound datatype, check if it is packed */
-    if(dt->shared->type == H5T_COMPOUND) {
+    if(dt->shared->type == H5T_COMPOUND)
         ret_value = (htri_t)(dt->shared->u.compnd.packed);
-    } /* end if */
 
     FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5T_is_packed() */
+} /* end H5T__is_packed() */
 
 
 /*-------------------------------------------------------------------------
@@ -638,7 +675,7 @@ H5T__update_packed(const H5T_t *dt)
 
         /* Now check if all members are packed */
         for(i = 0; i < dt->shared->u.compnd.nmembs; i++)
-            if(!H5T_is_packed(dt->shared->u.compnd.memb[i].type)) {
+            if(!H5T__is_packed(dt->shared->u.compnd.memb[i].type)) {
                 dt->shared->u.compnd.packed = FALSE;
                 break;
             } /* end if */
diff --git a/src/H5Tnative.c b/src/H5Tnative.c
index 8859102..357bb08 100644
--- a/src/H5Tnative.c
+++ b/src/H5Tnative.c
@@ -272,7 +272,7 @@ H5T__get_native_type(H5T_t *dtype, H5T_direction_t direction, size_t *struct_ali
 
                 /* Construct child compound type and retrieve a list of their IDs, offsets, total size, and alignment for compound type. */
                 for(u = 0; u < nmemb; u++) {
-                    if(NULL == (memb_type = H5T_get_member_type(dtype, u, H5T_COPY_TRANSIENT)))
+                    if(NULL == (memb_type = H5T_get_member_type(dtype, u)))
                         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "member type retrieval failed")
 
                     if(NULL == (comp_mname[u] = H5T__get_member_name(dtype, u)))
diff --git a/src/H5Tprivate.h b/src/H5Tprivate.h
index d8e98af..e05bb4e 100644
--- a/src/H5Tprivate.h
+++ b/src/H5Tprivate.h
@@ -59,7 +59,6 @@ struct H5S_t;
 typedef enum H5T_copy_t {
     H5T_COPY_TRANSIENT,
     H5T_COPY_ALL,
-    H5T_COPY_REOPEN
 } H5T_copy_t;
 
 /* Location of datatype information */
@@ -109,7 +108,8 @@ 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 H5T_t *H5T_copy_reopen(H5T_t *old_dt);
 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);
@@ -164,7 +164,7 @@ H5_DLL herr_t H5T_update_shared(H5T_t *type);
 
 /* Field functions (for both compound & enumerated types) */
 H5_DLL int H5T_get_nmembers(const H5T_t *dt);
-H5_DLL H5T_t *H5T_get_member_type(const H5T_t *dt, unsigned membno, H5T_copy_t method);
+H5_DLL H5T_t *H5T_get_member_type(const H5T_t *dt, unsigned membno);
 H5_DLL size_t H5T_get_member_offset(const H5T_t *dt, unsigned membno);
 
 /* Atomic functions */
diff --git a/src/H5Znbit.c b/src/H5Znbit.c
index fe0041c..2f79725 100644
--- a/src/H5Znbit.c
+++ b/src/H5Znbit.c
@@ -338,7 +338,7 @@ H5Z_calc_parms_compound(const H5T_t *type, size_t *cd_values_actual_nparms)
         H5T_class_t dtype_member_class; /* Compound datatype's member datatype's class */
 
         /* Get member datatype */
-        if(NULL == (dtype_member = H5T_get_member_type(type, u, H5T_COPY_TRANSIENT)))
+        if(NULL == (dtype_member = H5T_get_member_type(type, u)))
             HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, FAIL, "bad member datatype")
 
         /* Get member datatype's class */
@@ -695,7 +695,7 @@ H5Z_set_parms_compound(const H5T_t *type, unsigned *cd_values_index,
     /* For each member, set parameters */
     for(u = 0; u < nmembers; u++) {
         /* Get member datatype */
-        if(NULL == (dtype_member = H5T_get_member_type(type, u, H5T_COPY_TRANSIENT)))
+        if(NULL == (dtype_member = H5T_get_member_type(type, u)))
             HGOTO_ERROR(H5E_PLINE, H5E_BADTYPE, FAIL, "bad member datatype")
 
         /* Get member datatype's class */