Squashed commit of the following:

commit 45b0cbc71929930a874e1c09e0770aa64d0ae697
Author: Larry Knox <lrknox@hdfgroup.org>
Date:   Thu Apr 23 13:14:56 2020 -0500

    Add C++ warnings treated as error for autotools builds.

commit 6debcddcc766601799d5bd661bd60946f951a07e
Author: Larry Knox <lrknox@hdfgroup.org>
Date:   Fri Jun 19 16:50:03 2020 -0500

    Remove tests for develop branch from testh5cc.sh.in.
    Add @H5_ECXXFLAGS@ to AM_CXXFLAGS.

commit fed497e7f207313b2a133d3b68c942b7d7104b90
Author: Larry Knox <lrknox@hdfgroup.org>
Date:   Fri Jun 12 15:06:39 2020 -0500

    Merge pull request #2646 in HDFFV/hdf5 from ~LRKNOX/hdf5_lrk:develop to develop

    * commit '998c6470d78e14228695419c3b514c35ecf3d69e':
      Remove unnecessary version conditions for Clang compilers.

commit 92e52ce5c211bd1d3991a3b8bb67287ac7b652aa
Author: Larry Knox <lrknox@hdfgroup.org>
Date:   Wed Jun 10 18:53:45 2020 -0500

    Merge pull request #2639 in HDFFV/hdf5 from ~LRKNOX/hdf5_lrk:develop to develop

    * commit 'a33667faf226f5d8c9633bf537893e8fce1bf1f6':
      Add c++ to --enable-sanitize-checks option.

commit 2e802534fb997b81fa98fdd1c7d97d4310898e0d
Author: Larry Knox <lrknox@hdfgroup.org>
Date:   Wed Jun 10 15:18:36 2020 -0500

    Merge pull request #2633 in HDFFV/hdf5 from ~LRKNOX/hdf5_lrk:develop to develop

    * commit '20eab963899841c9a003baebead8e3bc07d9e127':
      Remove duplicate entries in MANIFEST.
      Make changes to CMake CompilerFlags.cmake files so extra flags are loaded for non-GNU compilers.
      Update new clang files to not pick up clang as vendor for pgCC. Add new files to MANIFEST Temporary demotion of 2 -Werror warning flags that fail on macos 10.12 Remove Production flag unknown to Apple clang.

commit 96ef60a58a23847a7da89a891f2415055ec2ab60
Author: Larry Knox <lrknox@hdfgroup.org>
Date:   Mon Jun 8 16:24:49 2020 -0500

    Merge pull request #2631 in HDFFV/hdf5 from ~LRKNOX/hdf5_lrk:develop to develop

    * commit 'b942a4d8a3e27317cac50ce37ff5302d477664d8':
      Clean up code to get clang version in config/linux-gnulibc1

commit 8a7c687da568e8b50b38fa53da1ca63759be6ec4
Author: Larry Knox <lrknox@hdfgroup.org>
Date:   Mon Jun 8 11:42:37 2020 -0500

    Merge pull request #2623 in HDFFV/hdf5 from ~LRKNOX/hdf5_lrk:develop to develop

    * commit 'c7626f79fdee4eee13925e240ef41e61f3367eab':
      Add flags from config/clang-warnings/*general files to H5 C and CXX flags for all versions of Clang and Clang++ compilers. Switched from cut to awk in testcheck_version.sh.in to avoid dependence on tab vs. " " in version definitions in H5public.h.
      Add files for adding warning flags for clang compilers in autotools configure.

commit db3ef7ff3c1ed79167cecef831501411cff8291f
Merge: 5a0f8d7 f9f1310
Author: Larry Knox <lrknox@hdfgroup.org>
Date:   Fri Jun 19 14:46:22 2020 -0500

    Merge branch 'hdf5_1_12' of https://bitbucket.hdfgroup.org/scm/~lrknox/hdf5_lrk into hdf5_1_12

commit 5a0f8d7940ae57b445f545a0abd7e303ce6924ee
Author: Larry Knox <lrknox@hdfgroup.org>
Date:   Wed Jun 10 20:15:41 2020 -0500

    Merge pull request #2636 in HDFFV/hdf5 from ~LRKNOX/hdf5_lrk:HDFFV-11000-update-testh5cc.sh.in-for-version to develop

    * commit '5c0bd670d6e9919c463fbc05de99e2ba55b0761e':
      Add tests for all version to H5_NO_DEPRECATED_SYMBOLS section and to section for current version, with and without default API version flags.
      HDFFV-11000:  update-testh5cc.sh.in to test sample versioned functions in HDF5 1.10, 1.12 and develop.

1 files changed, 58 insertions, 1 deletions

diff --git a/configure.ac b/configure.ac
index a74cd78..8585f5c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -104,13 +104,14 @@ 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.
+## H5_ECFLAGS (and company) are 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])
+AC_SUBST([H5_ECXXFLAGS])
 AC_SUBST([H5_JNIFLAGS])
 AC_SUBST([H5_JAVACFLAGS])
 AC_SUBST([H5_JAVAFLAGS])
@@ -288,6 +289,62 @@ while test -n "$hname"; do
   test "$hname_tmp" = "$hname" && break
 done
 
+##
+## Enable/disable sanitizer checks for clang compilers, initially address sanitizer
+##
+AC_MSG_CHECKING([for clang sanitizer checks])
+AC_ARG_ENABLE([sanitize-checks],
+              [AS_HELP_STRING([--enable-sanitize-checks=address],
+                              [(clang/clang++ compilers only) Enable sanitize checks.
+                               Address is useful for detecting issues dealing with 
+                               memory. See AddressSanitizer in config/sanitizer/README.md
+                               for more information.
+                               [default=none]
+                               ])],
+              [CLANG_SANITIZE_CHECKS=$enableval])
+
+# Set default
+if test "X-$CLANG_SANITIZE_CHECKS" = X- ; then
+  CLANG_SANITIZE_CHECKS=none
+fi
+
+if test "X$CC_BASENAME" = "Xclang"; then
+  AC_SUBST([CLANG_SANITIZE_CHECKS])
+
+  # There are several sanitizer tools.  At present we are testing 
+  # and describing only -fsanitizer=address with autotools.
+  case "X-$CLANG_SANITIZE_CHECKS" in
+    X-no|X-none)
+      CLANG_SANITIZE_CHECKS=none
+      CLANG_SANITIZE_LIST=
+      ;;
+    *)
+      CLANG_SANITIZE_LIST=$CLANG_SANITIZE_CHECKS
+      ;;
+  esac
+  AC_MSG_RESULT([$CLANG_SANITIZE_CHECKS])
+
+  # Other tools can be added to the list of checks
+  # The clang compiler doesn't support some of them; they should be
+  # checked before adding them to the list in the help message.
+  # The sanitizers/sanitizers.cmake file lists these options:
+  # address, memory, memoryWithOrigins, undefined, thread, leak, 
+  # 'address;undefined'.  Which and which combinations of these are 
+  #  supported varies by compiler version, but unsupported options
+  # or combinations will result in configure errors reported in config.log.
+  # Comma separated lists of sanitize options wil be entered intact in
+  # one -fsanitize=<list> flag.  Space separated lists will be entered in
+  # separate -fsanitize=<item> flags.
+  # NOTE: No sanity checking done here!
+  if test -n "$CLANG_SANITIZE_LIST"; then
+    H5_CFLAGS="$H5_CFLAGS -fno-omit-frame-pointer"
+    H5_CXXFLAGS="$H5_CXXFLAGS -fno-omit-frame-pointer"
+    for sanitizer in `echo $CLANG_SANITIZE_LIST`; do
+      H5_CFLAGS="$H5_CFLAGS -fsanitize=${sanitizer}"
+      H5_CXXFLAGS="$H5_CXXFLAGS -fsanitize=${sanitizer}"
+    done
+  fi
+fi
 
 ## ----------------------------------------------------------------------
 ## Determine build mode (debug, production, clean).