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, 200 insertions, 0 deletions

diff --git a/config/clang-cxxflags b/config/clang-cxxflags
new file mode 100644
index 0000000..edd62e7
--- /dev/null
+++ b/config/clang-cxxflags
@@ -0,0 +1,200 @@
+#                            -*- shell-script -*-
+#
+# 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.
+
+
+# This file should be sourced into configure if the compiler is the
+# Clang clang++ compiler or a derivative.  It is careful not to do anything
+# if the compiler is not Clang; otherwise 'cxx_flags_set' is set to 'yes'
+#
+
+#
+# For now, do not promote any warnings to errors.
+#
+PROMOTE_ERRORS_DFLT=no
+
+#
+# This filter rewrites -Werror= as -W, in that way demoting warnings
+# promoted to errors back to warnings, if PROMOTE_ERRORS is no.
+#
+demote_errors()
+{
+    if [ ${PROMOTE_ERRORS:-${PROMOTE_ERRORS_DFLT}} = no ]; then
+        sed 's,-Werror=,-W,g'
+    else
+        cat
+    fi
+}
+
+#
+# Prepend `$srcdir/config/clang-warnings/` to the filename suffix(es) given as
+# subroutine argument(s), remove comments starting with # and ending
+# at EOL, replace spans of whitespace (including newlines) with spaces,
+# and re-emit the file(s) thus filtered on the standard output stream.
+#
+load_clang_arguments()
+{
+    set -- $(for arg; do
+        sed 's,#.*$,,' $srcdir/config/clang-warnings/${arg}
+    done)
+    IFS=' ' echo "$*"
+}
+# Get the compiler version in a way that works for clang++
+# unless a compiler version is already known
+#
+#   cxx_vendor:    The compiler name: clang++
+#   cxx_version:   Version number: 6.0.0, 7.3.0, ... 10.0.1
+#
+if test "X-" = "X-$cxx_flags_set"; then
+    # clang++ -v will return version number following "clang" on Linux machines,
+    # but on Macs the version number will follow "Apple LLVM version"
+    cxx_version="`$CXX $CXXFLAGS $H5_CXXFLAGS -v 2>&1 |\
+        grep 'clang version' | sed 's/.*clang version \([-a-z0-9\.]*\).*/\1/'`"
+    if test -n "$cxx_version"; then
+        cxx_vendor="clang"
+    else
+        cxx_version="`$CXX $CXXFLAGS $H5_CXXFLAGS -v 2>&1 |\
+            grep 'Apple LLVM version' | sed 's/.*Apple LLVM version \([-a-z0-9\.]*\).*/\1/'`"
+        if test -n "$cxx_version"; then
+            cxx_vendor="Apple LLVM"
+        fi
+    fi
+    if test "X-" != "X-$cxx_version"; then
+
+        # Get the compiler version numbers
+        cxx_vers_major=`echo $cxx_version | cut -f1 -d.`
+        cxx_vers_minor=`echo $cxx_version | cut -f2 -d.`
+        cxx_vers_patch=`echo $cxx_version | cut -f3 -d.`
+        test -n "$cxx_vers_major" || cxx_vers_major=0
+        test -n "$cxx_vers_minor" || cxx_vers_minor=0
+        test -n "$cxx_vers_patch" || cxx_vers_patch=0
+    fi
+fi
+
+if test "X-clang" = "X-$cxx_vendor" -o "X-Apple LLVM" = "X-$cxx_vendor"; then
+    echo "compiler '$CXX' is $cxx_vendor-$cxx_version"
+    ###############################
+    # Architecture-specific flags #
+    ###############################
+
+    arch=
+    case "$host_os-$host_cpu" in
+        # FreeBSD sets the information from "uname -m" to the general machine
+        # architecture, not the specific CPU for the machine, so even our
+        # Pentium II Xeon server is set to "i386".  Once we know we are on a FreeBSD
+        # machine, use the "sysctl" command to get the CPU hardware model.
+        freebsd*-i386)
+            host_cpu_model=`sysctl -n hw.model`
+            case "$host_cpu_model" in
+                # Hmm.. this might not catch Celerons, but it won't hurt them either...
+                *Pro*|*II*|*III*|*IV*|*Athlon*)
+                    # architecture-specific optimizations cause problems
+                    # for some users who build binaries to be used on
+                    # multiple architectures.
+                    # arch="-march=i686"
+                ;;
+            esac
+            ;;
+
+        *-i686)
+                    # architecture-specific optimizations cause problems
+                    # for some users who build binaries to be used on
+                    # multiple architectures.
+                    # arch="-march=i686"
+            ;;
+    esac
+
+    case "$host_os-$host_cpu" in
+        # cygwin needs the "-std=c99" flag removed, so make
+        # a specific case for Cygwin without the flag and a default
+        # case to add the flag everywhere else
+        cygwin-*)
+            ;;
+
+        *)
+            H5_CXXFLAGS="$H5_CXXFLAGS -std=c++11"
+            ;;
+    esac
+
+    H5_CXXFLAGS="$H5_CXXFLAGS $arch"
+
+    ##############
+    # Production #
+    ##############
+
+    # NDEBUG is handled explicitly by the configure script
+    PROD_CXXFLAGS=
+
+    #########
+    # Debug #
+    #########
+
+    # NDEBUG is handled explicitly by the configure script
+    # -g is handled by the symbols flags
+    DEBUG_CXXFLAGS="-ftrapv -fno-common"
+
+    ###########
+    # Symbols #
+    ###########
+
+    NO_SYMBOLS_CXXFLAGS=
+    SYMBOLS_CXXFLAGS="-g -fno-omit-frame-pointer"
+
+    #############
+    # Profiling #
+    #############
+
+    PROFILE_CXXFLAGS="-pg"
+
+    ################
+    # Optimization #
+    ################
+
+    HIGH_OPT_CXXFLAGS="-O3"
+    DEBUG_OPT_CXXFLAGS="-g"
+    NO_OPT_CXXFLAGS="-O0"
+
+    ############
+    # Warnings #
+    ############
+
+    ###########
+    # General #
+    ###########
+
+    H5_CXXFLAGS="$H5_CXXFLAGS $(load_clang_arguments general)"
+    H5_ECXXFLAGS="$H5_ECXXFLAGS $(load_clang_arguments error-general)"
+
+    ######################
+    # Developer warnings #
+    ######################
+
+    NO_DEVELOPER_WARNING_CXXFLAGS=$(load_clang_arguments no-developer-general)
+    DEVELOPER_WARNING_CXXFLAGS=$(load_clang_arguments developer-general)
+
+    #############################
+    # Version-specific warnings #
+    #############################
+
+
+    #################
+    # Flags are set #
+    #################
+    cxx_flags_set=yes
+fi
+
+# Clear cxx info if no flags set
+if test "X$cxx_flags_set" = "X"; then
+    cxx_vendor=
+    cxx_version=
+fi
+