Merge pull request #593 in HDFFV/hdf5 from hdf5_1_8_19 to 1.8/masterhdf5-1_8_19

* commit 'c15238a38fdb3692466bc1218de4c5aeb420fdcc': (153 commits)
  Commit changes to release version strings in README.txt and RELEASE.txt from release.
  Put back link targets for dynamically loaded libraries in Makefile.ams that avoid linking with libhdf5 dependencies.  Some configurations failed unnecessarily to find and link with lz and lsz when these targets were removed.
  Update URL for obtaining source inINSTALL file.
  Disable building of libdynlib* dynamically loaded plugin test libraries on CYGWIN. Added known problem entry to RELEASE.txt. Set version for 1.8.19 release. Barbara updated contents of README.txt file.
  Moved libdynlib* plugin test libraries to noist_LT_LIBRARIES with added flag '-rpath /nowhere' to stop them being installed while keeping them from linking with libhdf5, etc. Incremented version to 1.8.19-pre1 and ran bin/release to create tar and zip files for testing.
  HDF5 1.8.19-pre1 released.
  Add RELEASE.txt entry for H5Dget_chunk_size.
  Remove test entries
  Ran bin/reconfigure after so number change.
  Update hl lib .so numbers:  new function was added. Update RELEASE.txt:  move H5DOread_chunks entry to new features, clarify entry for HDFFV-10051.
  Updated notes for test fixes and added bug fix for h5diff help text.
  Update h5vers and release scripts for 1.8.19 branch, set version to 1.8.19-pre1.
  Make script name consistent across product versions
  Update version to 1.8.19-pre1.
  Propagate .so number changes to Makefile.ins with bin/reconfigure.
  Add toolset option
  Update so version numbers according to the interface compatibility report.
  Update supported Platforms section. Remove empty sub-sections of New Features and Bugs Fixed sections.
  Add entries for HDFFV-10051 and HDFFV-9934 to RELEASE.txt.
  Correct spelling
  ...

1 files changed, 126 insertions, 89 deletions

diff --git a/config/cmake/HDFCompilerFlags.cmake b/config/cmake/HDFCompilerFlags.cmake
index c637c73..4ea8702 100644
--- a/config/cmake/HDFCompilerFlags.cmake
+++ b/config/cmake/HDFCompilerFlags.cmake
@@ -1,3 +1,14 @@
+#
+# 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://support.hdfgroup.org/ftp/HDF5/releases.
+# If you do not have access to either file, you may request a copy from
+# help@hdfgroup.org.
+
 #-----------------------------------------------------------------------------
 # Compiler specific flags : Shouldn't there be compiler tests for these
 #-----------------------------------------------------------------------------
@@ -12,21 +23,21 @@ if (CMAKE_COMPILER_IS_GNUCC)
     if (NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 5.0)
       set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fstdarg-opt")
     endif ()
-  endif (CMAKE_BUILD_TYPE MATCHES Debug)
-endif (CMAKE_COMPILER_IS_GNUCC)
-if (CMAKE_COMPILER_IS_GNUCXX)
+  endif ()
+endif ()
+if (CMAKE_COMPILER_IS_GNUCXX AND CMAKE_CXX_COMPILER_LOADED)
   if (CMAKE_BUILD_TYPE MATCHES Debug)
-    set (CMAKE_CXX_FLAGS "${CMAKE_ANSI_CFLAGS} ${CMAKE_CXX_FLAGS} -std=c99")
+    set (CMAKE_CXX_FLAGS "${CMAKE_ANSI_CFLAGS} ${CMAKE_CXX_FLAGS}")
     if (NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 5.0)
       set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Og -ftrapv -fno-common")
     endif ()
-  else (CMAKE_BUILD_TYPE MATCHES Debug)
-    set (CMAKE_CXX_FLAGS "${CMAKE_ANSI_CFLAGS} ${CMAKE_CXX_FLAGS} -std=c99")
+  else ()
+    set (CMAKE_CXX_FLAGS "${CMAKE_ANSI_CFLAGS} ${CMAKE_CXX_FLAGS}")
     if (NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 5.0)
       set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fstdarg-opt")
     endif ()
-  endif (CMAKE_BUILD_TYPE MATCHES Debug)
-endif (CMAKE_COMPILER_IS_GNUCXX)
+  endif ()
+endif ()
 
 #-----------------------------------------------------------------------------
 # Option to allow the user to disable compiler warnings
@@ -41,22 +52,22 @@ if (HDF5_DISABLE_COMPILER_WARNINGS)
     set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /w")
     string (REGEX REPLACE "(^| )([/-])W[0-9]( |$)" " " CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
     set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /w")
-  endif (MSVC)
+  endif ()
   if (WIN32)
     add_definitions (-D_CRT_SECURE_NO_WARNINGS)
-  endif (WIN32)
+  endif ()
   # Borland uses -w- to suppress warnings.
   if (BORLAND)
     set (HDF5_WARNINGS_BLOCKED 1)
     set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -w-")
-  endif (BORLAND)
+  endif ()
 
   # Most compilers use -w to suppress warnings.
   if (NOT HDF5_WARNINGS_BLOCKED)
     set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -w")
     set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -w")
-  endif (NOT HDF5_WARNINGS_BLOCKED)
-endif (HDF5_DISABLE_COMPILER_WARNINGS)
+  endif ()
+endif ()
 
 #-----------------------------------------------------------------------------
 # CDash is configured to only allow 3000 warnings, so
@@ -64,10 +75,22 @@ endif (HDF5_DISABLE_COMPILER_WARNINGS)
 #-----------------------------------------------------------------------------
 if (NOT MSVC AND CMAKE_COMPILER_IS_GNUCC)
   if (NOT ${CMAKE_SYSTEM_NAME} MATCHES "SunOS")
-    set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wundef -Wshadow -Wpointer-arith -Wbad-function-cast -Wcast-qual -Wcast-align -Wwrite-strings -Wconversion -Waggregate-return -Wstrict-prototypes -Wmissing-prototypes -Wmissing-declarations -Wredundant-decls -Wnested-externs -Winline")
-  else (NOT ${CMAKE_SYSTEM_NAME} MATCHES "SunOS")
+    set (CMAKE_C_FLAGS_5 "${CMAKE_C_FLAGS_5} -Wcast-qual")
+    set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wundef -Wshadow -Wpointer-arith -Wbad-function-cast -Wcast-align -Wwrite-strings -Wconversion -Waggregate-return -Wstrict-prototypes -Wmissing-prototypes -Wmissing-declarations -Wredundant-decls -Wnested-externs")
+  else ()
     set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -erroff=%none -DBSD_COMP")
-  endif (NOT ${CMAKE_SYSTEM_NAME} MATCHES "SunOS")
+  endif ()
+
+    #-----------------------------------------------------------------------------
+    # Option to allow the user to enable developer warnings
+    #-----------------------------------------------------------------------------
+    option (HDF5_ENABLE_DEV_WARNINGS "Enable HDF5 developer group warnings" OFF)
+    if (HDF5_ENABLE_DEV_WARNINGS)
+      set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Winline -Waggregate-return")
+    else ()
+      set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wno-unused-parameter -Wno-inline -Wno-aggregate-return")
+    endif ()
+
     # Append warning flags
     # Don't use the '-Wtraditional' flag, we're way past having K&R C code
     # set (H5_CFLAGS "${H5_CFLAGS} -Wtraditional")
@@ -83,75 +106,102 @@ if (NOT MSVC AND CMAKE_COMPILER_IS_GNUCC)
     set (H5_CFLAGS1 "${H5_CFLAGS1} -Wfloat-equal -Wmissing-format-attribute")
 
     # Append warning flags from gcc-3.2* case
-    set (H5_CFLAGS1 "${H5_CFLAGS1} -Wmissing-noreturn -Wpacked -Wdisabled-optimization")
+    set (H5_CFLAGS1 "${H5_CFLAGS1} -Wpacked -Wdisabled-optimization")
+    if (HDF5_ENABLE_DEV_WARNINGS)
+      set (H5_CFLAGS1 "${H5_CFLAGS1} -Wmissing-noreturn")
+    else ()
+      set (H5_CFLAGS1 "${H5_CFLAGS1} -Wno-missing-noreturn")
+    endif ()
 
     # Enable more format checking flags, beyond the basic -Wformat included
     # in -Wall
-    set (H5_CFLAGS1 "${H5_CFLAGS1} -Wformat=2")
-
-    # The "unreachable code" warning appears to be reliable now...
-    # (this warning was removed in gcc 4.5+)
-    if (NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 4.7)
-      set (H5_CFLAGS1 "${H5_CFLAGS1} -Wunreachable-code")
-    endif()
+    set (H5_CFLAGS1_5 "${H5_CFLAGS1_5} -Wformat=2")
 
     # Append warning flags from gcc-3.3* case
     set (H5_CFLAGS1 "${H5_CFLAGS1} -Wendif-labels")
 
     # Append warning flags from gcc-3.4* case
-    set (H5_CFLAGS2 "${H5_CFLAGS2} -Wdeclaration-after-statement -Wold-style-definition -Winvalid-pch")
+    set (H5_CFLAGS1 "${H5_CFLAGS1} -Wdeclaration-after-statement -Wold-style-definition -Winvalid-pch")
 
     # Append more extra warning flags that only gcc4.0+ know about
     set (H5_CFLAGS2 "${H5_CFLAGS2} -Wvariadic-macros -Winit-self -Wmissing-include-dirs -Wswitch-default -Wswitch-enum -Wunused-macros")
 
     # Append more extra warning flags that only gcc 4.1+ know about
-    set (H5_CFLAGS3 "${H5_CFLAGS3} -Wunsafe-loop-optimizations -Wc++-compat")
+    set (H5_CFLAGS2_5 "${H5_CFLAGS2_5} -Wunsafe-loop-optimizations")
+    set (H5_CFLAGS2 "${H5_CFLAGS2} -Wc++-compat")
 
     # Append more extra warning flags that only gcc 4.2+ know about
-    set (H5_CFLAGS3 "${H5_CFLAGS3} -Wstrict-overflow")
+    set (H5_CFLAGS2_5 "${H5_CFLAGS2_5} -Wstrict-overflow")
+    set (H5_CFLAGS2 "${H5_CFLAGS2} -Wno-strict-overflow")
 
     # Append more extra warning flags that only gcc 4.3+ know about
     #
     # Technically, variable-length arrays are part of the C99 standard, but
     #   we should approach them a bit cautiously... -QAK
-    set (H5_CFLAGS3 "${H5_CFLAGS3} -Wlogical-op -Wlarger-than=2048 -Wvla")
+    set (H5_CFLAGS2 "${H5_CFLAGS2} -Wlogical-op -Wlarger-than=2048 -Wvla")
 
     # Append more extra warning flags that only gcc 4.4+ know about
-    set (H5_CFLAGS4 "${H5_CFLAGS4} -Wsync-nand -Wframe-larger-than=16384 -Wpacked-bitfield-compat")
+    set (H5_CFLAGS2 "${H5_CFLAGS2} -Wsync-nand -Wframe-larger-than=16384 -Wpacked-bitfield-compat")
 
     # Append more extra warning flags that only gcc 4.5+ know about
     if (NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 4.5)
-      set (H5_CFLAGS4 "${H5_CFLAGS4} -Wstrict-overflow=5 -Wjump-misses-init -Wunsuffixed-float-constants")
-    endif()
+      set (H5_CFLAGS2_5 "${H5_CFLAGS2_5} -Wstrict-overflow=5 -Wjump-misses-init -Wunsuffixed-float-constants")
+      set (H5_CFLAGS2 "${H5_CFLAGS2} -Wjump-misses-init -Wunsuffixed-float-constants")
+    endif ()
 
     # Append more extra warning flags that only gcc 4.6+ know about
     if (NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 4.6)
-      set (H5_CFLAGS5 "${H5_CFLAGS5} -Wdouble-promotion -Wsuggest-attribute=const -Wtrampolines")
-    endif()
+      set (H5_CFLAGS2 "${H5_CFLAGS2} -Wdouble-promotion -Wtrampolines")
+      if (HDF5_ENABLE_DEV_WARNINGS)
+        set (H5_CFLAGS2 "${H5_CFLAGS2} -Wsuggest-attribute=const")
+      else ()
+        set (H5_CFLAGS2 "${H5_CFLAGS2} -Wno-suggest-attribute=const")
+      endif ()
+    endif ()
+
+    # The "unreachable code" warning appears to be reliable now...
+    # (this warning was removed in gcc 4.5+)
+    if (NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 4.7)
+      set (H5_CFLAGS2 "${H5_CFLAGS2} -Wunreachable-code")
+    endif ()
 
     # Append more extra warning flags that only gcc 4.7+ know about
     if (NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 4.7)
-      set (H5_CFLAGS5 "${H5_CFLAGS5} -Wstack-usage=8192 -Wvector-operation-performance -Wsuggest-attribute=pure -Wsuggest-attribute=noreturn")
-    endif()
+      set (H5_CFLAGS2 "${H5_CFLAGS2} -Wstack-usage=8192 -Wvector-operation-performance")
+      if (HDF5_ENABLE_DEV_WARNINGS)
+        set (H5_CFLAGS2 "${H5_CFLAGS2} -Wsuggest-attribute=pure -Wsuggest-attribute=noreturn")
+      else ()
+        set (H5_CFLAGS2 "${H5_CFLAGS2} -Wno-suggest-attribute=pure -Wno-suggest-attribute=noreturn")
+      endif ()
+    endif ()
 
     # Append more extra warning flags that only gcc 4.8+ know about
     if (NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 4.8)
-      set (H5_CFLAGS5 "${H5_CFLAGS5} -Wsuggest-attribute=format")
-    endif()
+      if (HDF5_ENABLE_DEV_WARNINGS)
+        set (H5_CFLAGS2 "${H5_CFLAGS2} -Wsuggest-attribute=format")
+      else ()
+        set (H5_CFLAGS2 "${H5_CFLAGS2} -Wno-suggest-attribute=format")
+      endif ()
+    endif ()
 
     # Append more extra warning flags that only gcc 4.9+ know about
     if (NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 4.9)
-      set (H5_CFLAGS5 "${H5_CFLAGS5} -Wdate-time -Wopenmp-simd")
-    endif()
+      set (H5_CFLAGS2 "${H5_CFLAGS2} -Wdate-time -Wopenmp-simd")
+    endif ()
 
     # (There was no release of gcc 5.0)
 
     # Append more extra warning flags that only gcc 5.1+ know about
     if (NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 5.1)
-      set (H5_CFLAGS6 "${H5_CFLAGS6} -Warray-bounds=2 -Wc99-c11-compat")
-    endif()
+      set (H5_CFLAGS3 "${H5_CFLAGS3} -Warray-bounds=2 -Wc99-c11-compat")
+    endif ()
 
-endif (NOT MSVC AND CMAKE_COMPILER_IS_GNUCC)
+    # Append more extra warning flags that only gcc 6.x+ know about
+    if (NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 6.0)
+      set (H5_CFLAGS4 "${H5_CFLAGS4} -Wnull-dereference -Wunused-const-variable -Wduplicated-cond -Whsa")
+    endif ()
+
+endif ()
 
 #-----------------------------------------------------------------------------
 # Option to allow the user to enable all warnings
@@ -159,16 +209,23 @@ endif (NOT MSVC AND CMAKE_COMPILER_IS_GNUCC)
 option (HDF5_ENABLE_ALL_WARNINGS "Enable all warnings" OFF)
 if (HDF5_ENABLE_ALL_WARNINGS)
   if (MSVC)
-    string (REGEX REPLACE "(^| )([/-])W[0-9]( |$)" " " CMAKE_C_FLAGS "${CMAKE_C_FLAGS}")
-    set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /Wall")
-    string (REGEX REPLACE "(^| )([/-])W[0-9]( |$)" " " CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
-    set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /Wall")
-  else (MSVC)
+    if (HDF5_ENABLE_DEV_WARNINGS)
+      string (REGEX REPLACE "(^| )([/-])W[0-9]( |$)" " " CMAKE_C_FLAGS "${CMAKE_C_FLAGS}")
+      set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /Wall /wd4668")
+      string (REGEX REPLACE "(^| )([/-])W[0-9]( |$)" " " CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
+      set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /Wall /wd4668")
+    else ()
+      string (REGEX REPLACE "(^| )([/-])W[0-9]( |$)" " " CMAKE_C_FLAGS "${CMAKE_C_FLAGS}")
+      set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /W3")
+      string (REGEX REPLACE "(^| )([/-])W[0-9]( |$)" " " CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
+      set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /W3")
+    endif ()
+  else ()
     if (CMAKE_COMPILER_IS_GNUCC)
-      set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -Wextra -pedantic ${H5_CFLAGS1} ${H5_CFLAGS2} ${H5_CFLAGS3} ${H5_CFLAGS4}")
-    endif (CMAKE_COMPILER_IS_GNUCC)
-  endif (MSVC)
-endif (HDF5_ENABLE_ALL_WARNINGS)
+      set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -Wextra -pedantic ${H5_CFLAGS1} ${H5_CFLAGS2}")
+    endif ()
+  endif ()
+endif ()
 
 #-----------------------------------------------------------------------------
 # Option to allow the user to enable warnings by groups
@@ -180,12 +237,12 @@ if (HDF5_ENABLE_GROUPZERO_WARNINGS)
     set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /W1")
     string (REGEX REPLACE "(^| )([/-])W[0-9]( |$)" " " CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
     set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /W1")
-  else (MSVC)
+  else ()
     if (CMAKE_COMPILER_IS_GNUCC)
       set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -Wextra -pedantic")
-    endif (CMAKE_COMPILER_IS_GNUCC)
-  endif (MSVC)
-endif (HDF5_ENABLE_GROUPZERO_WARNINGS)
+    endif ()
+  endif ()
+endif ()
 
 #-----------------------------------------------------------------------------
 # Option to allow the user to enable warnings by groups
@@ -197,10 +254,10 @@ if (HDF5_ENABLE_GROUPONE_WARNINGS)
     set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /W2")
     string (REGEX REPLACE "(^| )([/-])W[0-9]( |$)" " " CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
     set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /W2")
-  else (MSVC)
+  else ()
     set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${H5_CFLAGS1}")
-  endif (MSVC)
-endif (HDF5_ENABLE_GROUPONE_WARNINGS)
+  endif ()
+endif ()
 
 #-----------------------------------------------------------------------------
 # Option to allow the user to enable warnings by groups
@@ -212,10 +269,10 @@ if (HDF5_ENABLE_GROUPTWO_WARNINGS)
     set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /W3")
     string (REGEX REPLACE "(^| )([/-])W[0-9]( |$)" " " CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
     set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /W3")
-  else (MSVC)
+  else ()
     set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${H5_CFLAGS2}")
-  endif (MSVC)
-endif (HDF5_ENABLE_GROUPTWO_WARNINGS)
+  endif ()
+endif ()
 
 #-----------------------------------------------------------------------------
 # Option to allow the user to enable warnings by groups
@@ -227,10 +284,10 @@ if (HDF5_ENABLE_GROUPTHREE_WARNINGS)
     set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /W4")
     string (REGEX REPLACE "(^| )([/-])W[0-9]( |$)" " " CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
     set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /W4")
-  else (MSVC)
+  else ()
     set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${H5_CFLAGS3}")
-  endif (MSVC)
-endif (HDF5_ENABLE_GROUPTHREE_WARNINGS)
+  endif ()
+endif ()
 
 #-----------------------------------------------------------------------------
 # Option to allow the user to enable warnings by groups
@@ -239,28 +296,8 @@ option (HDF5_ENABLE_GROUPFOUR_WARNINGS "Enable group four warnings" OFF)
 if (HDF5_ENABLE_GROUPFOUR_WARNINGS)
   if (NOT MSVC)
     set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${H5_CFLAGS4}")
-  endif (NOT MSVC)
-endif (HDF5_ENABLE_GROUPFOUR_WARNINGS)
-
-#-----------------------------------------------------------------------------
-# Option to allow the user to enable warnings by groups
-#-----------------------------------------------------------------------------
-option (HDF5_ENABLE_GROUPFIVE_WARNINGS "Enable group five warnings" OFF)
-if (HDF5_ENABLE_GROUPFIVE_WARNINGS)
-  if (NOT MSVC)
-    set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${H5_CFLAGS5}")
-  endif (NOT MSVC)
-endif (HDF5_ENABLE_GROUPFIVE_WARNINGS)
-
-#-----------------------------------------------------------------------------
-# Option to allow the user to enable warnings by groups
-#-----------------------------------------------------------------------------
-option (HDF5_ENABLE_GROUPSIX_WARNINGS "Enable group six warnings" OFF)
-if (HDF5_ENABLE_GROUPSIX_WARNINGS)
-  if (NOT MSVC)
-    set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${H5_CFLAGS6}")
-  endif (NOT MSVC)
-endif (HDF5_ENABLE_GROUPSIX_WARNINGS)
+  endif ()
+endif ()
 
 #-----------------------------------------------------------------------------
 # This is in here to help some of the GCC based IDES like Eclipse
@@ -268,7 +305,7 @@ endif (HDF5_ENABLE_GROUPSIX_WARNINGS)
 #-----------------------------------------------------------------------------
 if (CMAKE_COMPILER_IS_GNUCC)
   set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fmessage-length=0")
-endif (CMAKE_COMPILER_IS_GNUCC)
-if (CMAKE_COMPILER_IS_GNUCXX)
+endif ()
+if (CMAKE_COMPILER_IS_GNUCXX AND CMAKE_CXX_COMPILER_LOADED)
   set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fmessage-length=0")
-endif (CMAKE_COMPILER_IS_GNUCXX)
+endif ()