Hdf5 1 10 merge warnings changes (#756)

* HDFFV-10865 - merge from dev, HDFArray perf fix.

* Remove duplicate setting

* Whitespace changes after clang format

* Undo version 11 clang format changes

* Merge CMake changes from develop

* test testing script merge from develop

* Update supported platforms

* PR#3 merge from develop

* Merge gcc 10 diagnostics option from develop

* Merge #318 OSX changes from develop

* Merge small changes from develop

* Minor non-space formatting changes

* #386 copyright corrections for java folder

* Merges from develop

#358 patches from vtk
#361 fix header guard spelling

* Merge updates

#358 patches from vtk
#361 fix header guard spelling

* format fix

* Fix missing underscore and make H5public.h closer to dev

* Merges from develop

#340 clang -Wformat-security warnings
#360 Fixed uninitialized warnings
header guard underscore cleanup
JNI cleanup

* format alignment

* Add missing test ref file

* Merge #380 from develop

* Finish java merges from develop

* Fix java issues with tests and javadoc

* Correct use of attribute access plist

* Remove debug code

* Remove unused variable

* Change file access to read only for java tests

* Split clang format operations.

* More javadoc comments

* Remove pre-split setting

* format source

* Change windows TS to use older VS.

* Mostly all javadoc fixes, one argument rename.

* synch file

* Merge of long double fix and compiler flags

* HDFFV-11229 merge changes from develop

* HDFFV-11229 correct test script

* HDFFV-11229 update autotools test script for two ref files

* HDFFV-11229 merge dev changes for long double display in tools

* Committing clang-format changes

* minor whitespace

* remove unneeded macro

* Committing clang-format changes

* Add "option" command for clang options

* Rework CMake add_custom to use the BYPRODUCTS argument

Update pkgconfig scripts for parallel builds.
Fix install COPYING file reference.
Remove unused round defines.
Change CMake default setting of BUILD_CPP to off.

* Fortran target depends

* Remove incorrect source attribute

* Revert define removal

* printf specifiers and VS2015 min changes

* Committing clang-format changes

* Add time struct

* TRILAB-227 and tools debug merges from develop

* Merge various changes from dev

* Issue #669 remove version from pkgcfg filename

* remove version from h5cc script

* doxygen changes merged from develop

* Committing clang-format changes

* Merge CMake fortran ninja changes from dev

* Enable fortran to gcc yaml

* Refactor Fortran CMake config tests and CMake test args

* Merge warnings files fixes from develop

Co-authored-by: github-actions <41898282+github-actions[bot]@users.noreply.github.com>

23 files changed, 608 insertions, 171 deletions

diff --git a/MANIFEST b/MANIFEST
index 258f340..fbbe7a6 100644
--- a/MANIFEST
+++ b/MANIFEST
@@ -136,6 +136,7 @@
 ./config/cygwin
 ./config/ibm-aix
 ./config/ibm-flags
+./config/intel-cxxflags
 ./config/intel-fflags
 ./config/intel-flags
 ./config/libhdf5.pc.in
@@ -147,6 +148,7 @@
 ./config/lt_vers.am
 ./config/Makefile.am.blank
 ./config/netbsd
+./config/pgi-cxxflags
 ./config/pgi-fflags
 ./config/pgi-flags
 ./config/solaris
@@ -172,6 +174,7 @@
 ./config/gnu-warnings/cxx-4.8
 ./config/gnu-warnings/cxx-4.9
 ./config/gnu-warnings/cxx-5
+./config/gnu-warnings/cxx-9
 ./config/gnu-warnings/cxx-error-5
 ./config/gnu-warnings/cxx-error-general
 ./config/gnu-warnings/cxx-noerror-5
@@ -196,8 +199,12 @@
 ./config/gnu-warnings/noerror-5
 ./config/gnu-warnings/noerror-8
 ./config/gnu-warnings/noerror-general
-./config/intel-warnings/ifort-general
+./config/intel-warnings/15
+./config/intel-warnings/18
+./config/intel-warnings/developer-general
 ./config/intel-warnings/general
+./config/intel-warnings/general-19
+./config/intel-warnings/ifort-general
 
 ./config/site-specific/BlankForm
 
diff --git a/config/clang-cxxflags b/config/clang-cxxflags
index e7ab6d8..23ba6a3 100644
--- a/config/clang-cxxflags
+++ b/config/clang-cxxflags
@@ -113,18 +113,6 @@ if test "X-clang" = "X-$cxx_vendor" -o "X-Apple LLVM" = "X-$cxx_vendor"; then
             ;;
     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"
 
     ##############
diff --git a/config/clang-warnings/noerror-general b/config/clang-warnings/noerror-general
index b570b23..f90c812 100644
--- a/config/clang-warnings/noerror-general
+++ b/config/clang-warnings/noerror-general
@@ -1,6 +1,8 @@
 #
-# HDF5 code should not trigger the following warnings under any
-# circumstances, so ask the compiler to treat them as errors:
+# These warnings will be treated as errors, using the error-general file,
+# when HDF5_ENABLE_WARNINGS_AS_ERRORS is set to true for CMake or
+# the --enable-warnings-as-errors option is specified for configure.
+#   Otherwise this file will be used to treat them as warnings.
 #
 -Wbad-function-cast
 -Wimplicit-function-declaration
diff --git a/config/cmake/HDFCXXCompilerFlags.cmake b/config/cmake/HDFCXXCompilerFlags.cmake
index 8bcfb14..64ec010 100644
--- a/config/cmake/HDFCXXCompilerFlags.cmake
+++ b/config/cmake/HDFCXXCompilerFlags.cmake
@@ -86,9 +86,11 @@ if (NOT MSVC AND NOT MINGW)
     # warnings that are emitted. If you need it, add it at configure time.
     if (CMAKE_CXX_COMPILER_ID STREQUAL "Intel")
       ADD_H5_FLAGS (HDF5_CMAKE_CXX_FLAGS "${HDF5_SOURCE_DIR}/config/intel-warnings/general")
+      if(NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 15.0)
+        ADD_H5_FLAGS (H5_CXXFLAGS "${HDF5_SOURCE_DIR}/config/intel-warnings/15")
+      endif()
       if(NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 18.0)
-        list (APPEND H5_CXXFLAGS "-Wextra-tokens -Wformat -Wformat-security -Wic-pointer -Wshadow")
-        list (APPEND H5_CXXFLAGS "-Wsign-compare -Wtrigraphs -Wwrite-strings")
+        ADD_H5_FLAGS (H5_CXXFLAGS "${HDF5_SOURCE_DIR}/config/intel-warnings/18")
       endif()
     elseif (CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
       if (CMAKE_COMPILER_IS_GNUCXX AND CMAKE_CXX_COMPILER_LOADED
@@ -117,21 +119,20 @@ if (NOT MSVC AND NOT MINGW)
   #-----------------------------------------------------------------------------
   if (HDF5_ENABLE_DEV_WARNINGS)
     message (STATUS "....HDF5 developer group warnings are enabled")
-  #  if (CMAKE_CXX_COMPILER_ID STREQUAL "Intel")
-  #    list (APPEND H5_CXXFLAGS "-Winline -Wreorder -Wport -Wstrict-aliasing")
-  #  elseif (CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
-    if (CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
-      # autotools always add the C flags with the CXX flags
+    if (CMAKE_CXX_COMPILER_ID STREQUAL "Intel")
+      ADD_H5_FLAGS (H5_CXXFLAGS "${HDF5_SOURCE_DIR}/config/intel-warnings/developer-general")
+    elseif (CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
+      # Use the C warnings as CXX warnings are the same
       ADD_H5_FLAGS (H5_CXXFLAGS "${HDF5_SOURCE_DIR}/config/gnu-warnings/developer-general")
-  #  elseif (CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
-  #    ADD_H5_FLAGS (H5_CXXFLAGS "${HDF5_SOURCE_DIR}/config/clang-warnings/developer-general")
+    elseif (CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
+      ADD_H5_FLAGS (H5_CXXFLAGS "${HDF5_SOURCE_DIR}/config/clang-warnings/developer-general")
     endif ()
   else ()
     if (CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
-      # autotools always add the C flags with the CXX flags
+      # Use the C warnings as CXX warnings are the same
       ADD_H5_FLAGS (H5_CXXFLAGS "${HDF5_SOURCE_DIR}/config/gnu-warnings/no-developer-general")
-  #  elseif (CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
-  #    ADD_H5_FLAGS (H5_CXXFLAGS "${HDF5_SOURCE_DIR}/config/clang-warnings/no-developer-general")
+    elseif (CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
+      ADD_H5_FLAGS (H5_CXXFLAGS "${HDF5_SOURCE_DIR}/config/clang-warnings/no-developer-general")
     endif ()
   endif ()
 
@@ -139,14 +140,15 @@ if (NOT MSVC AND NOT MINGW)
     # Technically, variable-length arrays are part of the C99 standard, but
     #   we should approach them a bit cautiously... Only needed for gcc 4.X
     if (CMAKE_CXX_COMPILER_VERSION VERSION_LESS 5.0 AND CMAKE_C_COMPILER_VERSION VERSION_GREATER_EQUAL 4.8)
-      # autotools always add the C flags with the CXX flags
+      # Use the C warnings as CXX warnings are the same
       ADD_H5_FLAGS (H5_CXXFLAGS "${HDF5_SOURCE_DIR}/config/gnu-warnings/4.8-4.last")
     endif ()
 
     # Append more extra warning flags that only gcc 4.8+ knows about
     if (NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.8)
-      ADD_H5_FLAGS (H5_CXXFLAGS "${HDF5_SOURCE_DIR}/config/gnu-warnings/4.8")
+      ADD_H5_FLAGS (H5_CXXFLAGS "${HDF5_SOURCE_DIR}/config/gnu-warnings/cxx-4.8")
       if (HDF5_ENABLE_DEV_WARNINGS)
+        # Use the C warnings as CXX warnings are the same
         ADD_H5_FLAGS (H5_CXXFLAGS "${HDF5_SOURCE_DIR}/config/gnu-warnings/developer-4.8")
       else ()
         ADD_H5_FLAGS (H5_CXXFLAGS "${HDF5_SOURCE_DIR}/config/gnu-warnings/no-developer-4.8")
@@ -155,8 +157,7 @@ if (NOT MSVC AND NOT MINGW)
 
     # Append more extra warning flags that only gcc 4.9+ knows about
     if (NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.9)
-      # autotools always add the C flags with the CXX flags
-      ADD_H5_FLAGS (H5_CXXFLAGS "${HDF5_SOURCE_DIR}/config/gnu-warnings/4.9")
+      # Use the C warnings as CXX warnings are the same
       ADD_H5_FLAGS (H5_CXXFLAGS "${HDF5_SOURCE_DIR}/config/gnu-warnings/cxx-4.9")
     endif ()
 
@@ -173,16 +174,16 @@ if (NOT MSVC AND NOT MINGW)
 
     # Append more extra warning flags that only gcc 6.x+ knows about
     if (NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 6.0)
-      # autotools always add the C flags with the CXX flags
+      # Use the C warnings as CXX warnings are the same
       ADD_H5_FLAGS (H5_CXXFLAGS "${HDF5_SOURCE_DIR}/config/gnu-warnings/6")
     endif ()
 
     # Append more extra warning flags that only gcc 7.x+ knows about
     if (NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 7.0)
-      # autotools always add the C flags with the CXX flags
+      # Use the C warnings as CXX warnings are the same
       ADD_H5_FLAGS (H5_CXxFLAGS2 "${HDF5_SOURCE_DIR}/config/gnu-warnings/7")
       if (HDF5_ENABLE_DEV_WARNINGS)
-        # autotools always add the C flags with the CXX flags
+      # Use the C warnings as CXX warnings are the same
         ADD_H5_FLAGS (H5_CXXFLAGS "${HDF5_SOURCE_DIR}/config/gnu-warnings/developer-7")
       #else ()
       #  ADD_H5_FLAGS (H5_CXXFLAGS "${HDF5_SOURCE_DIR}/config/gnu-warnings/no-developer-7")
@@ -191,15 +192,15 @@ if (NOT MSVC AND NOT MINGW)
 
     # Append more extra warning flags that only gcc 8.x+ knows about
     if (NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 8.0)
-      # autotools always add the C flags with the CXX flags
+      # Use the C warnings as CXX warnings are the same
       ADD_H5_FLAGS (H5_CXXFLAGS "${HDF5_SOURCE_DIR}/config/gnu-warnings/8")
-      #if (HDF5_ENABLE_WARNINGS_AS_ERRORS)
-      #  ADD_H5_FLAGS (H5_CXXFLAGS "${HDF5_SOURCE_DIR}/config/gnu-warnings/error-8")
-      #else ()
-      #  ADD_H5_FLAGS (H5_CXXFLAGS "${HDF5_SOURCE_DIR}/config/gnu-warnings/noerror-8")
-      #endif ()
+      if (HDF5_ENABLE_WARNINGS_AS_ERRORS)
+        ADD_H5_FLAGS (H5_CXXFLAGS "${HDF5_SOURCE_DIR}/config/gnu-warnings/error-8")
+      else ()
+        ADD_H5_FLAGS (H5_CXXFLAGS "${HDF5_SOURCE_DIR}/config/gnu-warnings/noerror-8")
+      endif ()
       if (HDF5_ENABLE_DEV_WARNINGS)
-        # autotools always add the C flags with the CXX flags
+        # Use the C warnings as CXX warnings are the same
         ADD_H5_FLAGS (H5_CXXFLAGS "${HDF5_SOURCE_DIR}/config/gnu-warnings/developer-8")
       else ()
         # autotools always add the C flags with the CXX flags
@@ -209,14 +210,26 @@ if (NOT MSVC AND NOT MINGW)
 
     # Append more extra warning flags that only gcc 9.x+ knows about
     if (NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 9.0)
-      # autotools always add the C flags with the CXX flags
-      ADD_H5_FLAGS (H5_CXXFLAGS "${HDF5_SOURCE_DIR}/config/gnu-warnings/9")
+      # Use the C warnings as CXX warnings are the same
+      ADD_H5_FLAGS (H5_CXXFLAGS "${HDF5_SOURCE_DIR}/config/gnu-warnings/cxx-9")
     endif ()
-  endif ()
-else ()
-  if (NOT MINGW)
-    list (APPEND HDF5_CMAKE_CXX_FLAGS "/EHsc")
+
+    # Append more extra warning flags that only gcc 9.3+ knows about
+    if (NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 9.3)
+      # do not use C warnings, gnu-warnings 9.3, no cxx warniings
+      # ADD_H5_FLAGS (H5_CXXFLAGS "${HDF5_SOURCE_DIR}/config/gnu-warnings/9.3")
     endif ()
+
+    # Append more extra warning flags that only gcc 10.x+ knows about
+    if (NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 10.0)
+      if (HDF5_ENABLE_DEV_WARNINGS)
+        # Use the C warnings as CXX warnings are the same
+        ADD_H5_FLAGS (H5_CXXFLAGS "${HDF5_SOURCE_DIR}/config/gnu-warnings/developer-10")
+      #else ()
+      #  ADD_H5_FLAGS (H5_CXXFLAGS "${HDF5_SOURCE_DIR}/config/gnu-warnings/no-developer-10")
+      endif ()
+    endif ()
+  endif ()
 endif ()
 
 #-----------------------------------------------------------------------------
diff --git a/config/cmake/HDFCompilerFlags.cmake b/config/cmake/HDFCompilerFlags.cmake
index 0775f59..e38a92b 100644
--- a/config/cmake/HDFCompilerFlags.cmake
+++ b/config/cmake/HDFCompilerFlags.cmake
@@ -108,14 +108,13 @@ if (NOT MSVC AND NOT MINGW)
     # warnings that are emitted. If you need it, add it at configure time.
     if (CMAKE_C_COMPILER_ID STREQUAL "Intel")
       ADD_H5_FLAGS (HDF5_CMAKE_C_FLAGS "${HDF5_SOURCE_DIR}/config/intel-warnings/general")
-      list (APPEND H5_CFLAGS "-Wcomment -Wdeprecated -Wmain -Wmissing-declarations -Wmissing-prototypes -Wp64 -Wpointer-arith")
-      list (APPEND H5_CFLAGS "-Wreturn-type -Wstrict-prototypes -Wuninitialized")
-      list (APPEND H5_CFLAGS "-Wunknown-pragmas -Wunused-function -Wunused-variable")
+      if(NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 15.0)
+        ADD_H5_FLAGS (H5_CFLAGS "${HDF5_SOURCE_DIR}/config/intel-warnings/15")
+      endif()
       # this is just a failsafe
       list (APPEND H5_CFLAGS "-finline-functions")
       if(NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 18.0)
-        list (APPEND H5_CFLAGS "-Wextra-tokens -Wformat -Wformat-security -Wic-pointer -Wshadow")
-        list (APPEND H5_CFLAGS "-Wsign-compare -Wtrigraphs -Wwrite-strings")
+        ADD_H5_FLAGS (H5_CFLAGS "${HDF5_SOURCE_DIR}/config/intel-warnings/18")
       endif()
     elseif (CMAKE_C_COMPILER_ID STREQUAL "GNU")
       # Add general CFlags for GCC versions 4.8 and above
@@ -153,7 +152,7 @@ if (NOT MSVC AND NOT MINGW)
   if (HDF5_ENABLE_DEV_WARNINGS)
     message (STATUS "....HDF5 developer group warnings are enabled")
     if (CMAKE_C_COMPILER_ID STREQUAL "Intel")
-      list (APPEND H5_CFLAGS "-Winline -Wreorder -Wport -Wstrict-aliasing")
+      ADD_H5_FLAGS (H5_CFLAGS "${HDF5_SOURCE_DIR}/config/intel-warnings/developer-general")
     elseif (CMAKE_C_COMPILER_ID STREQUAL "GNU" AND CMAKE_C_COMPILER_VERSION VERSION_GREATER_EQUAL 4.8)
       ADD_H5_FLAGS (H5_CFLAGS "${HDF5_SOURCE_DIR}/config/gnu-warnings/developer-general")
     elseif (CMAKE_C_COMPILER_ID MATCHES "[Cc]lang")
diff --git a/config/gnu-cxxflags b/config/gnu-cxxflags
index cba8298..b2ba08d 100644
--- a/config/gnu-cxxflags
+++ b/config/gnu-cxxflags
@@ -183,7 +183,6 @@ if test "X-g++" = "X-$cxx_vendor"; then
     # Warnings #
     ############
 
-# First load the C warnings then add CXX warnings (if needed)
 
     ###########
     # General #
@@ -199,6 +198,7 @@ if test "X-g++" = "X-$cxx_vendor"; then
         # Developer warnings #
         ######################
 
+        # Use the C warnings as CXX warnings are the same
         NO_DEVELOPER_WARNING_CXXFLAGS=$(load_gnu_arguments no-developer-general)
         DEVELOPER_WARNING_CXXFLAGS=$(load_gnu_arguments developer-general)
 
@@ -210,6 +210,7 @@ if test "X-g++" = "X-$cxx_vendor"; then
 
     # GCC 4.8 through the end of GCC 4 series
     if test $cxx_vers_major -eq 4 -a $cxx_vers_minor -ge 8; then
+        # Use the C warnings as CXX warnings are the same
         H5_CXXFLAGS="$H5_CXXFLAGS $(load_gnu_arguments 4.8-4.last)"
     fi
 
@@ -220,13 +221,13 @@ if test "X-g++" = "X-$cxx_vendor"; then
     # gcc >= 4.8
     if test $cxx_vers_major -ge 5 -o $cxx_vers_major -eq 4 -a $cxx_vers_minor -ge 8; then
         H5_CXXFLAGS="$H5_CXXFLAGS $(load_gnu_arguments cxx-4.8)"
+        # Use the C warnings as CXX warnings are the same
         DEVELOPER_WARNING_CXXFLAGS="$DEVELOPER_WARNING_CXXFLAGS $(load_gnu_arguments developer-4.8)"
         NO_DEVELOPER_WARNING_CXXFLAGS="$NO_DEVELOPER_WARNING_CXXFLAGS $(load_gnu_arguments no-developer-4.8)"
     fi
 
     # gcc >= 4.9
     if test $cxx_vers_major -ge 5 -o $cxx_vers_major -eq 4 -a $cxx_vers_minor -ge 9; then
-        H5_CXXFLAGS="$H5_CXXFLAGS $(load_gnu_arguments 4.9)"
         H5_CXXFLAGS="$H5_CXXFLAGS $(load_gnu_arguments cxx-4.9)"
     fi
 
@@ -239,27 +240,40 @@ if test "X-g++" = "X-$cxx_vendor"; then
 
     # gcc >= 6
     if test $cxx_vers_major -ge 6; then
+        # Use the C warnings as CXX warnings are the same
         H5_CXXFLAGS="$H5_CXXFLAGS $(load_gnu_arguments 6)"
     fi
 
     # gcc >= 7
     if test $cxx_vers_major -ge 7; then
+        # Use the C warnings as CXX warnings are the same
         H5_CXXFLAGS="$H5_CXXFLAGS $(load_gnu_arguments 7)"
         DEVELOPER_WARNING_CXXFLAGS="$DEVELOPER_WARNING_CXXFLAGS $(load_gnu_arguments developer-7)"
     fi
 
     # gcc 8
     if test $cxx_vers_major -ge 8; then
+        # Use the C warnings as CXX warnings are the same
         H5_CXXFLAGS="$H5_CXXFLAGS $(load_gnu_arguments 8)"
         #H5_ECXXFLAGS="$H5_ECXXFLAGS $(load_gnu_arguments error-8)"
         #H5_NECXXFLAGS="$H5_NECXXFLAGS $(load_gnu_arguments noerror-8)"
+        # Use the C warnings as CXX warnings are the same
         DEVELOPER_WARNING_CXXFLAGS="$DEVELOPER_WARNING_CXXFLAGS $(load_gnu_arguments developer-8)"
         NO_DEVELOPER_WARNING_CXXFLAGS="$NO_DEVELOPER_WARNING_CXXFLAGS $(load_gnu_arguments no-developer-8)"
     fi
 
     # gcc 9
     if test $cxx_vers_major -ge 9; then
-        H5_CXXFLAGS="$H5_CXXFLAGS $(load_gnu_arguments 9)"
+        H5_CXXFLAGS="$H5_CXXFLAGS $(load_gnu_arguments cxx-9)"
+    fi
+
+    # gcc >= 9.3
+        # no cxx warnings, do NOT use C warnings
+
+    # gcc >= 10
+    if test $cxx_vers_major -ge 10; then
+        # Use the C warnings as CXX warnings are the same
+        DEVELOPER_WARNING_CFLAGS="$DEVELOPER_WARNING_CFLAGS $(load_gnu_arguments developer-10)"
     fi
 
     #################
diff --git a/config/gnu-flags b/config/gnu-flags
index 01533de..3e4ceb2 100644
--- a/config/gnu-flags
+++ b/config/gnu-flags
@@ -207,9 +207,9 @@ if test "X-gcc" = "X-$cc_vendor"; then
         H5_ECFLAGS="$H5_ECFLAGS $(load_gnu_arguments error-general)"
         H5_NECFLAGS="$H5_NECFLAGS $(load_gnu_arguments noerror-general)"
 
-    ######################
-    # Developer warnings #
-    ######################
+        ######################
+        # Developer warnings #
+        ######################
 
         NO_DEVELOPER_WARNING_CFLAGS=$(load_gnu_arguments no-developer-general)
         DEVELOPER_WARNING_CFLAGS=$(load_gnu_arguments developer-general)
diff --git a/config/gnu-warnings/cxx-4.9 b/config/gnu-warnings/cxx-4.9
index 046d6db..30553bd 100644
--- a/config/gnu-warnings/cxx-4.9
+++ b/config/gnu-warnings/cxx-4.9
@@ -1 +1,2 @@
+-Wdate-time
 -Wopenmp-simd
diff --git a/config/gnu-warnings/cxx-9 b/config/gnu-warnings/cxx-9
new file mode 100644
index 0000000..8f843a4
--- /dev/null
+++ b/config/gnu-warnings/cxx-9
@@ -0,0 +1,4 @@
+-Wattribute-alias=2
+-Wmissing-profile
+# Turn this on when the C++ wrappers obey the Rule of Five
+-Wno-deprecated-copy
diff --git a/config/gnu-warnings/developer-10 b/config/gnu-warnings/developer-10
index fcd460d..022c97f 100644
--- a/config/gnu-warnings/developer-10
+++ b/config/gnu-warnings/developer-10
@@ -1,6 +1,2 @@
 # New warning
 -Warith-conversion
-
-# Enable static analysis of program flow
--fanalyzer
--fdiagnostics-path-format=none
diff --git a/config/gnu-warnings/noerror-general b/config/gnu-warnings/noerror-general
index f5b4afb..80c1975 100644
--- a/config/gnu-warnings/noerror-general
+++ b/config/gnu-warnings/noerror-general
@@ -1,6 +1,8 @@
 #
-# HDF5 code should not trigger the following warnings under any
-# circumstances, so ask the compiler to treat them as errors:
+# These warnings will be treated as errors, using the error-general file,
+# when HDF5_ENABLE_WARNINGS_AS_ERRORS is set to true for CMake or
+# the --enable-warnings-as-errors option is specified for configure.
+#   Otherwise this file will be used to treat them as warnings.
 #
 -Wbad-function-cast
 -Wimplicit-function-declaration
diff --git a/config/intel-cxxflags b/config/intel-cxxflags
new file mode 100644
index 0000000..484100f
--- /dev/null
+++ b/config/intel-cxxflags
@@ -0,0 +1,184 @@
+#                            -*- shell-script -*-
+#
+# Copyright by The HDF Group.
+# 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://www.hdfgroup.org/licenses.
+# 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
+# Intel icpc compiler or a derivative.  It is careful not to do anything
+# if the compiler is not Intel; otherwise `cxx_flags_set' is set to `yes'
+#
+
+#
+# Prepend `$srcdir/config/intel-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_intel_arguments()
+{
+    set -- $(for arg; do
+        sed 's,#.*$,,' $srcdir/config/intel-warnings/${arg}
+    done)
+    IFS=' ' echo "$*"
+}
+
+# Get the compiler version in a way that works for icpc
+# icpc unless a compiler version is already known
+#
+#   cxx_vendor:    The compiler name: icpc
+#   cxx_version:   Version number: 8.0
+#
+if test X = "X$cxx_flags_set"; then
+    cxx_version="`$CXX $CXXFLAGS $H5_CXXFLAGS -V 2>&1 |grep 'Version'`"
+    if test X != "X$cxx_version"; then
+        cxx_vendor=icpc
+        cxx_version=`echo $cxx_version |sed 's/.*Version \([-a-z0-9\.\-]*\).*/\1/'`
+        echo "compiler '$CXX' is Intel $cxx_vendor-$cxx_version"
+
+        # Some version numbers
+        # Intel version numbers are of the form: "major.minor"
+        cxx_vers_major=`echo $cxx_version | cut -f1 -d.`
+        cxx_vers_minor=`echo $cxx_version | cut -f2 -d.`
+        #cxx_vers_patch=`echo $cxx_version | cut -f2 -d.`
+        test -n "$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
+        cxx_vers_all=`expr $cxx_vers_major '*' 1000000 + $cxx_vers_minor '*' 1000 + $cxx_vers_patch`
+    fi
+fi
+
+# Common Intel flags for various situations
+if test "X-icpc" = "X-$cxx_vendor"; then
+    # Insert section about version specific problems from compiler flags here,
+    # if necessary.
+
+    arch=
+    # Architecture-specific flags
+    # Nothing currently. (Uncomment code below and modify to add any)
+    #case "$host_os-$host_cpu" in
+    #    *-i686)
+    #        arch="-march=i686"
+    #        ;;
+    #esac
+
+    # Host-specific flags
+    # Nothing currently. (Uncomment code below and modify to add any)
+    #case "`hostname`" in
+    #    sleipnir.ncsa.uiuc.edu)
+    #        arch="$arch -pipe"
+    #        ;;
+    #esac
+
+    ###########
+    # General #
+    ###########
+
+    H5_CXXFLAGS="$H5_CXXFLAGS $arch"
+
+    ##############
+    # Production #
+    ##############
+
+    PROD_CXXFLAGS=
+
+    #########
+    # Debug #
+    #########
+
+    # NDEBUG is handled explicitly in configure
+    # -g is handled by the symbols flags
+    DEBUG_CXXFLAGS=
+
+    ###########
+    # Symbols #
+    ###########
+
+    NO_SYMBOLS_CXXFLAGS="-Wl,-s"
+    SYMBOLS_CXXFLAGS="-g"
+
+    #############
+    # Profiling #
+    #############
+
+    PROFILE_CXXFLAGS="-p"
+
+    ################
+    # Optimization #
+    ################
+
+    HIGH_OPT_CXXFLAGS="-O3"
+    DEBUG_OPT_CXXFLAGS="-O0"
+    NO_OPT_CXXFLAGS="-O0"
+
+    ############
+    # Warnings #
+    ############
+
+    ###########
+    # General #
+    ###########
+
+    # Add various general warning flags in intel-warnings.
+    # Use the C warnings as CXX warnings are the same
+    H5_CXXFLAGS="$H5_CXXFLAGS $(load_intel_arguments general)"
+
+    ######################
+    # Developer warnings #
+    ######################
+
+    # Use the C warnings as CXX warnings are the same
+    #NO_DEVELOPER_WARNING_CXXFLAGS=$(load_intel_arguments no-developer-general)
+    #DEVELOPER_WARNING_CXXFLAGS=$(load_intel_arguments developer-general)
+
+    #############################
+    # Version-specific warnings #
+    #############################
+
+    # intel == 8.0
+    if test $cxx_vers_major -eq 8 -a $cxx_vers_minor -eq 0; then
+        # v8.0 -O3 infinite loops when compiling test/tselect.c. Use -O2.
+        HIGH_OPT_CFLAGS="-O2"
+    fi
+
+    # intel == 10
+    if test $cxx_vers_major -eq 10; then
+        HIGH_OPT_CFLAGS="-O1"
+    fi
+
+    # intel >= 15
+    if test $cxx_vers_major -ge 15; then
+        # Use the C warnings as CXX warnings are the same
+        H5_CXXFLAGS="$H5_CXXFLAGS $(load_intel_arguments 15)"
+    fi
+
+    # intel >= 18
+    if test $cxx_vers_major -ge 18; then
+        # Use the C warnings as CXX warnings are the same
+        H5_CXXFLAGS="$H5_CXXFLAGS $(load_intel_arguments 18)"
+    fi
+
+    # intel <= 19
+    if test $cxx_vers_major -le 19; then
+        # Use the C warnings as CXX warnings are the same
+        H5_CXXFLAGS="$H5_CXXFLAGS $(load_intel_arguments general-19)"
+    fi
+
+    #################
+    # Flags are set #
+    #################
+    cxx_flags_set=yes
+fi
+
+# Clear cxx info if no flags set
+if test "X-$cxx_flags_set" = "X-"; then
+    cxx_vendor=
+    cxx_version=
+fi
diff --git a/config/intel-fflags b/config/intel-fflags
index b759dfa..42c1781 100644
--- a/config/intel-fflags
+++ b/config/intel-fflags
@@ -56,13 +56,17 @@ if test X = "X$f9x_flags_set"; then
     fi
 fi
 
-# Common Intel flags for various situations
 if test "X-ifort" = "X-$f9x_vendor"; then
-    # Insert section about version specific problems from compiler flags here,
-    # if necessary.
+
+    FC_BASENAME=ifort
+    F9XSUFFIXFLAG=""
+    FSEARCH_DIRS=""
+
+    ###############################
+    # Architecture-specific flags #
+    ###############################
 
     arch=
-    # Architecture-specific flags
     # Nothing currently. (Uncomment code below and modify to add any)
     #case "$host_os-$host_cpu" in
     #    *-i686)
@@ -78,32 +82,55 @@ if test "X-ifort" = "X-$f9x_vendor"; then
     #        ;;
     #esac
 
-    # General
-    FC_BASENAME=ifort
-    F9XSUFFIXFLAG=""
-    FSEARCH_DIRS=""
-    H5_FCFLAGS="$H5_FCFLAGS -stand:f03 -free"
-    H5_FCFLAGS="$H5_FCFLAGS $(load_intel_arguments ifort-general)"
+    ##############
+    # Production #
+    ##############
 
-    # Production
     PROD_FCFLAGS=
 
-    # Debug
+    #########
+    # Debug #
+    #########
+
     DEBUG_FCFLAGS="-check all"
 
-    # Symbols
-    SYMBOLS_FCFLAGS="-g"
+    ###########
+    # Symbols #
+    ###########
+
     NO_SYMBOLS_FCFLAGS=
+    SYMBOLS_FCFLAGS="-g"
+
+    #############
+    # Profiling #
+    #############
 
-    # Profiling
-    # Use this for profiling with gprof
     PROFILE_FCFLAGS="-p"
 
-    # Optimization
+    ################
+    # Optimization #
+    ################
+
     HIGH_OPT_FCFLAGS="-O3"
     DEBUG_OPT_FCFLAGS=
     NO_OPT_FCFLAGS=
 
+    ############
+    # Warnings #
+    ############
+
+    ###########
+    # General #
+    ###########
+
+    H5_FCFLAGS="$H5_FCFLAGS -stand:f03 -free"
+    H5_FCFLAGS="$H5_FCFLAGS $(load_intel_arguments ifort-general)"
+
+    #############################
+    # Version-specific warnings #
+    #############################
+
+
     #################
     # Flags are set #
     #################
@@ -116,4 +143,3 @@ if test "X-$f9x_flags_set" = "X-"; then
   f9x_version=
 fi
 
-
diff --git a/config/intel-flags b/config/intel-flags
index 409ffe9..f46da0a 100644
--- a/config/intel-flags
+++ b/config/intel-flags
@@ -78,26 +78,43 @@ if test "X-icc" = "X-$cc_vendor"; then
     #        ;;
     #esac
 
-    # General
+    ###########
+    # General #
+    ###########
+
     # Default to C99 standard.
     H5_CFLAGS="$H5_CFLAGS $arch -std=c99"
 
-    # Production
+    ##############
+    # Production #
+    ##############
+
     PROD_CFLAGS=
 
-    # Debug
+    #########
+    # Debug #
+    #########
+
     # NDEBUG is handled explicitly in configure
     DEBUG_CFLAGS=
 
-    # Symbols
-    SYMBOLS_CFLAGS="-g"
+    ###########
+    # Symbols #
+    ###########
+
     NO_SYMBOLS_CFLAGS="-Wl,-s"
+    SYMBOLS_CFLAGS="-g"
+
+    #############
+    # Profiling #
+    #############
 
-    # Profiling
-    # Use this for profiling with gprof
     PROFILE_CFLAGS="-p"
 
-    # Optimization
+    ################
+    # Optimization #
+    ################
+
     HIGH_OPT_CFLAGS="-O3"
     DEBUG_OPT_CFLAGS="-O0"
     NO_OPT_CFLAGS="-O0"
@@ -110,32 +127,51 @@ if test "X-icc" = "X-$cc_vendor"; then
     # General #
     ###########
 
+    # Add various general warning flags in intel-warnings.
     H5_CFLAGS="$H5_CFLAGS $(load_intel_arguments general)"
 
+    ######################
+    # Developer warnings #
+    ######################
+
+    #NO_DEVELOPER_WARNING_CFLAGS=$(load_intel_arguments no-developer-general)
+    #DEVELOPER_WARNING_CFLAGS=$(load_intel_arguments developer-general)
+
     #############################
     # Version-specific warnings #
     #############################
 
-case "$cc_vendor-$cc_version" in
-    icc-1[5-6]*)
-        H5_CFLAGS="$H5_CFLAGS -Wcomment -Wdeprecated -Wextra-tokens -Wformat -Wformat-security -Wmain -Wmissing-declarations -Wmissing-prototypes -Wp64 -Wpointer-arith -Wreturn-type -Wshadow -Wstrict-prototypes -Wtrigraphs -Wuninitialized -Wunknown-pragmas -Wunused-function -Wunused-variable -Wwrite-strings"
-        ;;
-    icc-10*)
-        HIGH_OPT_CFLAGS="-O1"
-        ;;
-    icc-8.0*)
+    # intel == 8.0
+    if test $cc_vers_major -eq 8 -a $cc_vers_minor -eq 0; then
         # v8.0 -O3 infinite loops when compiling test/tselect.c. Use -O2.
         HIGH_OPT_CFLAGS="-O2"
-        ;;
-    icc-*)
-        ;;
-esac
+    fi
+
+    # intel == 10
+    if test $cc_vers_major -eq 10; then
+        HIGH_OPT_CFLAGS="-O1"
+    fi
+
+    # intel >= 15
+    if test $cc_vers_major -ge 15; then
+        H5_CFLAGS="$H5_CFLAGS $(load_intel_arguments 15)"
+    fi
+
+    # intel >= 18
+    if test $cc_vers_major -ge 18; then
+        H5_CFLAGS="$H5_CFLAGS $(load_intel_arguments 18)"
+    fi
+
+    # intel <= 19
+    # this file has warnings only available before oneapi versions
+    if test $cc_vers_major -le 19; then
+        H5_CFLAGS="$H5_CFLAGS $(load_intel_arguments general-19)"
+    fi
 
     #################
     # Flags are set #
     #################
     cc_flags_set=yes
-
 fi
 
 # Clear cc info if no flags set
diff --git a/config/intel-warnings/15 b/config/intel-warnings/15
new file mode 100644
index 0000000..6746f97
--- /dev/null
+++ b/config/intel-warnings/15
@@ -0,0 +1,19 @@
+-Wcomment
+-Wdeprecated
+-Wextra-tokens
+-Wformat
+-Wformat-security
+-Wmain
+-Wmissing-declarations
+-Wmissing-prototypes
+-Wp64
+-Wpointer-arith
+-Wreturn-type
+-Wshadow
+-Wstrict-prototypes
+-Wtrigraphs
+-Wuninitialized
+-Wunknown-pragmas
+-Wunused-function
+-Wunused-variable
+-Wwrite-strings
diff --git a/config/intel-warnings/18 b/config/intel-warnings/18
new file mode 100644
index 0000000..565b47a
--- /dev/null
+++ b/config/intel-warnings/18
@@ -0,0 +1,8 @@
+-Wextra-tokens
+-Wformat
+-Wformat-security
+-Wic-pointer
+-Wshadow
+-Wsign-compare
+-Wtrigraphs
+-Wwrite-strings
diff --git a/config/intel-warnings/developer-general b/config/intel-warnings/developer-general
new file mode 100644
index 0000000..fae56f0
--- /dev/null
+++ b/config/intel-warnings/developer-general
@@ -0,0 +1,4 @@
+-Winline
+-Wreorder
+-Wport
+-Wstrict-aliasing
diff --git a/config/intel-warnings/general b/config/intel-warnings/general
index d0b2e25..bd866b6 100644
--- a/config/intel-warnings/general
+++ b/config/intel-warnings/general
@@ -1,2 +1 @@
 -Wall
--Wcheck
\ No newline at end of file
diff --git a/config/intel-warnings/general-19 b/config/intel-warnings/general-19
new file mode 100644
index 0000000..e35af30
--- /dev/null
+++ b/config/intel-warnings/general-19
@@ -0,0 +1,2 @@
+# this is only available before oneapi versions
+-Wcheck
diff --git a/config/linux-gnulibc1 b/config/linux-gnulibc1
index 0fef161..d952c4e 100644
--- a/config/linux-gnulibc1
+++ b/config/linux-gnulibc1
@@ -199,9 +199,16 @@ if test -z "$CXX"; then
   CXX_BASENAME=g++
 fi
 
+# Figure out Intel CXX compiler flags
+# Do this ahead of GNU to avoid icpc being detected as g++
+. $srcdir/config/intel-cxxflags
+
 # Figure out GNU CXX compiler flags
 . $srcdir/config/gnu-cxxflags
 
+# Figure out PGI CXX compiler flags
+. $srcdir/config/pgi-cxxflags
+
 # Figure out Clang CXX compiler flags
 . $srcdir/config/clang-cxxflags
 
@@ -314,6 +321,9 @@ fi
 # check if the compiler_version_info is already set
 if test -z "$cxx_version_info"; then
 case $CXX in
+    *pgc++*)
+        cxx_version_info=`$CXX $CXXFLAGS $H5_CXXFLAGS -V 2>&1 | grep 'pgc++'`
+        ;;
     *g++*)
         cxx_version_info=`$CXX $CXXFLAGS $H5_CXXFLAGS --version 2>&1 |\
             grep 'GCC' | sed 's/\(.*(GCC) [-a-z0-9\. ]*\).*/\1/'`
@@ -322,10 +332,6 @@ case $CXX in
         cxx_version_info=`$CXX $CXXFLAGS $H5_CXXFLAGS -V 2>&1 | grep 'Version' |\
             sed 's/\(Intel.* Compiler\).*\( Version [a-z0-9\.]*\).*\( Build [0-9]*\)/\1\2\3/'`
         ;;
-    *pgCC*)
-        cxx_version_info=`$CXX $CXXFLAGS $H5_CXXFLAGS -V 2>&1 | grep 'pgCC'`
-        ;;
-
     *mpicxx*)
         cxx_version_info=`$CXX $CXXFLAGS $H5_CXXFLAGS -v 2>&1 | grep 'version' |\
             sed 's/^[a-z0-9]* for //' |\
diff --git a/config/pgi-cxxflags b/config/pgi-cxxflags
new file mode 100644
index 0000000..5fc74ae
--- /dev/null
+++ b/config/pgi-cxxflags
@@ -0,0 +1,100 @@
+#                            -*- shell-script -*-
+#
+# Copyright by The HDF Group.
+# All rights reserved.
+#
+# This file is part of HDF5.  The full HDF5 copyright notice, including
+# terms governing use, modification, and redistribution, is contained in
+# the COPYING file, which can be found at the root of the source code
+# distribution tree, or in https://www.hdfgroup.org/licenses.
+# If you do not have access to either file, you may request a copy from
+# help@hdfgroup.org.
+
+
+# This file should be sourced into configure if the compiler is the
+# PGI pgc++ compiler or a derivative.  It is careful not to do anything
+# if the compiler is not PGI; otherwise `cxx_flags_set' is set to `yes'
+#
+
+# Get the compiler version in a way that works for pgc++
+# pgc++ unless a compiler version is already known
+#
+#   cxx_vendor:    The compiler name: pgc++
+#   cxx_version:   Version number: 5.0-2, 5.2-2
+#
+if test X = "X$cxx_flags_set"; then
+    cxx_version="`$CXX $CXXFLAGS -V 2>&1 |grep '^pgc++ '`"
+    if test X != "X$cxx_version"; then
+        cxx_vendor=`echo $cxx_version |sed 's/\([a-z]*++\).*/\1/'`
+        cxx_version=`echo $cxx_version |sed 's/pgc++ \([-a-z0-9\.\-]*\).*/\1/'`
+        echo "compiler '$CXX' is PGI $cxx_vendor-$cxx_version"
+
+        # Some version numbers
+        # PGI version numbers are of the form: "major.minor-patch"
+        cxx_vers_major=`echo $cxx_version | cut -f1 -d.`
+        cxx_vers_minor=`echo $cxx_version | cut -f2 -d. | cut -f1 -d-`
+        cxx_vers_patch=`echo $cxx_version | cut -f2 -d. | cut -f2 -d-`
+        test -n "$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
+        cxx_vers_all=`expr $cxx_vers_major '*' 1000000 + $cxx_vers_minor '*' 1000 + $cxx_vers_patch`
+    fi
+fi
+
+# Common PGI flags for various situations
+if test "X-pgc++" = "X-$cxx_vendor"; then
+
+    ###########
+    # General #
+    ###########
+
+    H5_CXXFLAGS="$H5_CXXFLAGS -Minform=warn"
+
+    ##############
+    # Production #
+    ##############
+
+    PROD_CXXFLAGS=
+
+    #########
+    # Debug #
+    #########
+
+    # NDEBUG is handled explicitly in configure
+    # -g is handled by the symbols flags
+    DEBUG_CXXFLAGS="-Mbounds"
+
+    ###########
+    # Symbols #
+    ###########
+
+    NO_SYMBOLS_CXXFLAGS="-s"
+    SYMBOLS_CXXFLAGS="-g"
+
+    #############
+    # Profiling #
+    #############
+
+    PROFILE_CXXFLAGS="-Mprof=func,line"
+    # Use this for profiling with gprof
+    #PROFILE_CXXFLAGS="-pg"
+
+    ################
+    # Optimization #
+    ################
+
+    HIGH_OPT_CXXFLAGS="-O4"
+    DEBUG_OPT_CXXFLAGS="-gopt -O2"
+    NO_OPT_CXXFLAGS="-O0"
+
+    #################
+    # Flags are set #
+    #################
+    cxx_flags_set=yes
+fi
+
+# Clear cxx info if no flags set
+if test "X-$cxx_flags_set" = "X-"; then
+    cxx_vendor=
+    cxx_version=
+fi
diff --git a/config/pgi-fflags b/config/pgi-fflags
index 3171695..6401d8d 100644
--- a/config/pgi-fflags
+++ b/config/pgi-fflags
@@ -1,4 +1,4 @@
-#							-*- shell-script -*-
+#                            -*- shell-script -*-
 #
 # Copyright by The HDF Group.
 # Copyright by the Board of Trustees of the University of Illinois.
@@ -45,11 +45,12 @@ fi
 
 # Common PGI flags for various situations
 if test "X-pgf90" = "X-$f9x_vendor"; then
-    # Insert section about version specific problems from gnu-flags here, if
-    # necessary.
+
+    ###############################
+    # Architecture-specific flags #
+    ###############################
 
     arch=
-    # Architecture-specific flags
     # Nothing currently. (Uncomment code below and modify to add any)
     #case "$host_os-$host_cpu" in
     #    *-i686)
@@ -65,15 +66,10 @@ if test "X-pgf90" = "X-$f9x_vendor"; then
     #        ;;
     #esac
 
-    # General
-    FC_BASENAME=pgf90
-    Fortran_COMPILER_ID=PGI
-    F9XSUFFIXFLAG=""
-    FSEARCH_DIRS=""
-    # Uncomment the following to add something specific for FCFLAGS.
-    #FCFLAGS="$FCFLAGS"
+    ##############
+    # Production #
+    ##############
 
-    # Production
     # Check for MPI wrapper being used and tweak down compiler options
     # Comment out the Tweaking since it caused problems to mpich1.2.6.
     # Need to investigate the reasons to tweak.
@@ -84,24 +80,55 @@ if test "X-pgf90" = "X-$f9x_vendor"; then
     #fi
     PROD_FCFLAGS="-fast -Mnoframe"
 
-    # Debug
+    #########
+    # Debug #
+    #########
+
     DEBUG_FCFLAGS="-Mbounds -Mchkptr -Mdclchk"
 
-    # Symbols
-    SYMBOLS_FCFLAGS="-g"
+    ###########
+    # Symbols #
+    ###########
+
     NO_SYMBOLS_FCFLAGS="-s"
+    SYMBOLS_FCFLAGS="-g"
+
+    #############
+    # Profiling #
+    #############
 
-    # Profiling
     PROFILE_FCFLAGS="-Mprof=func,line"
     # Use this for profiling with gprof
     #PROFILE_FCFLAGS="-pg"
 
-    # Optimization
+    ################
+    # Optimization #
+    ################
+
     HIGH_OPT_FCFLAGS=
     DEBUG_OPT_FCFLAGS=
     NO_OPT_FCFLAGS=
 
-    # Flags are set
+    ############
+    # Warnings #
+    ############
+
+    ###########
+    # General #
+    ###########
+
+    FC_BASENAME=pgf90
+    Fortran_COMPILER_ID=PGI
+    F9XSUFFIXFLAG=""
+    FSEARCH_DIRS=""
+    # Uncomment the following to add something specific for FCFLAGS.
+    #FCFLAGS="$FCFLAGS"
+
+
+
+    #################
+    # Flags are set #
+    #################
     f9x_flags_set=yes
 fi
 
@@ -111,4 +138,3 @@ if test "X-$f9x_flags_set" = "X-"; then
   f9x_version=
 fi
 
-
diff --git a/config/pgi-flags b/config/pgi-flags
index e1bec00..b197a1c 100644
--- a/config/pgi-flags
+++ b/config/pgi-flags
@@ -1,4 +1,4 @@
-#							-*- shell-script -*-
+#                            -*- shell-script -*-
 #
 # Copyright by The HDF Group.
 # Copyright by the Board of Trustees of the University of Illinois.
@@ -45,8 +45,8 @@ fi
 
 # Common PGI flags for various situations
 if test "X-pgcc" = "X-$cc_vendor"; then
-    # Insert section about version specific problems from gnu-flags here, if
-    # necessary.
+    # Insert section about version specific problems from compiler flags here,
+    # if necessary.
 
     arch=
     # Architecture-specific flags
@@ -65,58 +65,59 @@ if test "X-pgcc" = "X-$cc_vendor"; then
     #        ;;
     #esac
 
-    # General
-    H5_CFLAGS="$H5_CFLAGS $arch -c99 -Minform=inform"
-
-    # Production
-    case "$cc_vendor-$cc_version" in
-      pgcc-10.6*)
-        PROD_CFLAGS=
-        ;;
-      pgcc-9.*)
-        PROD_CFLAGS=
-        ;;
-      *)
-        PROD_CFLAGS="-fast"
-        ;;
-    esac
-
-    # Debug
+    ###########
+    # General #
+    ###########
+
+    # Default to C99 standard.
+    H5_CFLAGS="$H5_CFLAGS $arch -c99 -Minform=warn"
+
+    ##############
+    # Production #
+    ##############
+
+    # NDEBUG is handled explicitly by the configure script
+    PROD_CFLAGS="-fast"
+
+    #########
+    # Debug #
+    #########
+
     # NDEBUG is handled explicitly by the configure script
+    # -g is handled by the symbols flags
     DEBUG_CFLAGS="-Mbounds"
 
-    # Symbols
-    SYMBOLS_CFLAGS="-g"
+    ###########
+    # Symbols #
+    ###########
+
     NO_SYMBOLS_CFLAGS="-s"
+    SYMBOLS_CFLAGS="-g"
+
+    #############
+    # Profiling #
+    #############
 
-    # Profiling
     PROFILE_CFLAGS="-Mprof=func,line"
     # Use this for profiling with gprof
     #PROFILE_CFLAGS="-pg"
 
-    # Optimization
-    case "$cc_vendor-$cc_version" in
-      # Tweak down compiler optimizations for v10.6, it has a bug
-      pgcc-10.6*)
-        HIGH_OPT_CFLAGS="-O1"
-        ;;
-      # Tweak down compiler optimizations for v9.x
-      pgcc-9.*)
-        HIGH_OPT_CFLAGS="-O1"
-        ;;
-      *)
-        HIGH_OPT_CFLAGS=
-        ;;
-    esac
-    DEBUG_OPT_CFLAGS=
-    NO_OPT_CFLAGS=
-
-    # Flags are set
+    ################
+    # Optimization #
+    ################
+
+    HIGH_OPT_CFLAGS="-O4"
+    DEBUG_OPT_CFLAGS="-gopt -O2"
+    NO_OPT_CFLAGS="-O0"
+
+    #################
+    # Flags are set #
+    #################
     cc_flags_set=yes
 fi
 
 # Clear cc info if no flags set
 if test "X-$cc_flags_set" = "X-"; then
-  cc_vendor=
-  cc_version=
+    cc_vendor=
+    cc_version=
 fi