Disable memory alloc sanity checks by default for Autotools debug bui…

…lds (HDFGroup#1468)

configure.ac

@@ -2782,9 +2782,11 @@ AC_ARG_ENABLE([memory-alloc-sanity-check],
                               [Enable this option to turn on internal memory
                               allocation sanity checking.  This could cause
                               more memory use and somewhat slower allocation.
-                              This option is orthogonal to the
-                              --enable-using-memchecker option.
-                               [default=yes if debug build, otherwise no]
+                              This option may also cause issues with HDF5
+                              filter plugins, so should not be enabled if
+                              filters are to be used.  This option is orthogonal
+                              to the --enable-using-memchecker option.
+                               [default=no]
                               ])],
               [MEMORYALLOCSANITYCHECK=$enableval])
 
@@ -2794,11 +2796,10 @@ AC_SUBST([MEMORYALLOCSANITYCHECK])
 
 ## Set default
 if test "X-$MEMORYALLOCSANITYCHECK" = X- ; then
-  if test "X-$BUILD_MODE" = "X-debug" ; then
-    MEMORYALLOCSANITYCHECK=yes
-  else
-    MEMORYALLOCSANITYCHECK=no
-  fi
+# Should consider enabling this option by default for
+# 'developer' builds if that build mode is added in
+# the future
+  MEMORYALLOCSANITYCHECK=no
 fi
 
 case "X-$MEMORYALLOCSANITYCHECK" in

release_docs/RELEASE.txt

@@ -56,6 +56,25 @@ New Features
 
       (ADB - 2022/03/11)
 
+    - HDF5 memory allocation sanity checking is now off by default for
+      Autotools debug builds
+
+      HDF5 can be configured to perform sanity checking on internal memory
+      allocations by adding heap canaries to these allocations. However,
+      enabling this option can cause issues with external filter plugins
+      when working with (reallocating/freeing/allocating and passing back)
+      buffers.
+
+      Previously, this option was off by default for all CMake build types,
+      but only off by default for non-debug Autotools builds. Since debug
+      is the default build mode for HDF5 when built from source with
+      Autotools, this can result in surprising segfaults that don't occur
+      when an application is built against a release version of HDF5.
+      Therefore, this option is now off by default for all build types
+      across both CMake and Autotools.
+
+      (JTH - 2022/03/01)
+
     - Refactored the utils folder.
 
       Added subfolder test and moved the 'swmr_check_compat_vfd.c file'