Remove another couple of H5E_clear_stack calls (#4968)

Also cleans up the links test, which had a ton of copy-and-pasted incorrect negative error checks (Calling TEST_ERROR within H5E_BEGIN_TRY / H5E_END_TRY pairs will goto out of the pair, leaving errors suppressed).

release_docs/RELEASE.txt

@@ -198,6 +198,11 @@ Bug Fixes since HDF5-1.16.0 release
 ===================================
     Library
     -------
+    - Fixed a bug in the H5Oexists and H5Oexists_by_name API routines that
+      would cause those routines to return FAIL instead of FALSE when checking
+      the existence of a non-existent object with a file ID instead of a
+      group ID.
+
     - Only clear FE_INVALID when that symbol is present on the system
 
       When we initialize the floating-point types at library startup, it's

src/H5Dvirtual.c

@@ -890,25 +890,26 @@ H5D__virtual_open_source_dset(const H5D_t *vdset, H5O_storage_virtual_ent_t *vir
 
     if (src_file) {
         H5G_loc_t src_root_loc; /* Object location of source file root group */
+        bool      exists = false;
 
         /* Set up the root group in the destination file */
         if (NULL == (src_root_loc.oloc = H5G_oloc(H5G_rootof(src_file))))
             HGOTO_ERROR(H5E_DATASET, H5E_BADVALUE, FAIL, "unable to get object location for root group");
         if (NULL == (src_root_loc.path = H5G_nameof(H5G_rootof(src_file))))
             HGOTO_ERROR(H5E_DATASET, H5E_BADVALUE, FAIL, "unable to get path for root group");
 
-        /* Try opening the source dataset */
-        source_dset->dset = H5D__open_name(&src_root_loc, source_dset->dset_name,
-                                           vdset->shared->layout.storage.u.virt.source_dapl);
+        /* Check if the source dataset exists */
+        if (H5G_loc_exists(&src_root_loc, source_dset->dset_name, &exists /*out*/) < 0)
+            HGOTO_ERROR(H5E_OHDR, H5E_CANTFIND, FAIL, "can't check object's existence");
 
-        /* Dataset does not exist */
-        if (NULL == source_dset->dset) {
-            /* Reset the error stack */
-            H5E_clear_stack();
+        /* Dataset exists */
+        if (exists) {
+            /* Try opening the source dataset */
+            if (NULL ==
+                (source_dset->dset = H5D__open_name(&src_root_loc, source_dset->dset_name,
+                                                    vdset->shared->layout.storage.u.virt.source_dapl)))
+                HGOTO_ERROR(H5E_DATASET, H5E_CANTOPENOBJ, FAIL, "unable to open source dataset");
 
-            source_dset->dset_exists = false;
-        } /* end if */
-        else {
             /* Dataset exists */
             source_dset->dset_exists = true;
 
@@ -919,7 +920,10 @@ H5D__virtual_open_source_dset(const H5D_t *vdset, H5O_storage_virtual_ent_t *vir
                 virtual_ent->source_space_status = H5O_VIRTUAL_STATUS_CORRECT;
             } /* end if */
         }     /* end else */
-    }         /* end if */
+        else
+            /* Dataset does not exist */
+            source_dset->dset_exists = false;
+    } /* end if */
 
 done:
     /* Release resources */

src/H5Gloc.c

@@ -581,26 +581,21 @@ H5G__loc_exists_cb(H5G_loc_t H5_ATTR_UNUSED *grp_loc /*in*/, const char H5_ATTR_
                    const H5O_link_t H5_ATTR_UNUSED *lnk, H5G_loc_t *obj_loc, void *_udata /*in,out*/,
                    H5G_own_loc_t *own_loc /*out*/)
 {
-    bool  *exists    = (bool *)_udata; /* User data passed in */
-    herr_t ret_value = SUCCEED;        /* Return value */
+    bool *exists = (bool *)_udata; /* User data passed in */
 
-    FUNC_ENTER_PACKAGE
+    FUNC_ENTER_PACKAGE_NOERR
 
     /* Check if the name in this group resolved to a valid object */
     if (obj_loc == NULL)
-        if (lnk)
-            *exists = false;
-        else
-            HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, FAIL, "no object or link info?");
+        *exists = false;
     else
         *exists = true;
 
     /* Indicate that this callback didn't take ownership of the group *
      * location for the object */
     *own_loc = H5G_OWN_NONE;
 
-done:
-    FUNC_LEAVE_NOAPI(ret_value)
+    FUNC_LEAVE_NOAPI(SUCCEED)
 } /* end H5G__loc_exists_cb() */
 
 /*-------------------------------------------------------------------------

src/H5Gtraverse.c

@@ -180,7 +180,11 @@ H5G__traverse_ud(const H5G_loc_t *grp_loc /*in,out*/, const H5O_link_t *lnk, H5G
     if ((cur_grp = H5VL_wrap_register(H5I_GROUP, grp, false)) < 0)
         HGOTO_ERROR(H5E_SYM, H5E_CANTREGISTER, FAIL, "unable to register group");
 
-        /* User-defined callback function */
+    /* Pause recording errors, if we are just checking for object's existence */
+    if (target & H5G_TARGET_EXISTS)
+        H5E_pause_stack();
+
+        /* Invoke user-defined callback function */
 #ifndef H5_NO_DEPRECATED_SYMBOLS
     /* (Backwardly compatible with v0 H5L_class_t traversal callback) */
     if (link_class->version == H5L_LINK_CLASS_T_VERS_0)
@@ -194,13 +198,14 @@ H5G__traverse_ud(const H5G_loc_t *grp_loc /*in,out*/, const H5O_link_t *lnk, H5G
                                         H5CX_get_dxpl());
 #endif /* H5_NO_DEPRECATED_SYMBOLS */
 
+    /* Resume recording errors, if we were just checking for object's existence */
+    if (target & H5G_TARGET_EXISTS)
+        H5E_resume_stack();
+
     /* Check for failing to locate the object */
     if (cb_return < 0) {
         /* Check if we just needed to know if the object exists */
         if (target & H5G_TARGET_EXISTS) {
-            /* Clear any errors from the stack */
-            H5E_clear_stack();
-
             /* Indicate that the object doesn't exist */
             *obj_exists = false;