Merge topic 'gcc-features'

37ed860a GNU C++: record that -fvisibility-inlines-hidden is available since 4.0
94a8ee6f GNU C: record that C99 is available since at least 3.4
940bf6a4 Tests/Module/WCDH: only use -Werror=undef compiler flag if actually supported
f26ca5a1 Tests/Module/WCDH: write multi_file_compiler_detection.h before using it

6 files changed, 39 insertions, 23 deletions

diff --git a/Help/manual/cmake-compile-features.7.rst b/Help/manual/cmake-compile-features.7.rst
index 4f48ad9..448fe9a 100644
--- a/Help/manual/cmake-compile-features.7.rst
+++ b/Help/manual/cmake-compile-features.7.rst
@@ -338,6 +338,14 @@ versions specified for each:
 * ``SunPro``: Oracle SolarisStudio version 12.4.
 * ``Intel``: Intel compiler versions 12.1 through 17.0.
 
+CMake is currently aware of the :prop_tgt:`C standards <C_STANDARD>`
+and :prop_gbl:`compile features <CMAKE_C_KNOWN_FEATURES>` available from
+the following :variable:`compiler ids <CMAKE_<LANG>_COMPILER_ID>` as of the
+versions specified for each:
+
+* all compilers and versions listed above for C++
+* ``GNU``: GNU compiler versions 3.4 through 5.0.
+
 CMake is currently aware of the :prop_tgt:`CUDA standards <CUDA_STANDARD>`
 from the following :variable:`compiler ids <CMAKE_<LANG>_COMPILER_ID>` as of the
 versions specified for each:
diff --git a/Help/release/dev/gcc-features.rst b/Help/release/dev/gcc-features.rst
new file mode 100644
index 0000000..c6959ab
--- /dev/null
+++ b/Help/release/dev/gcc-features.rst
@@ -0,0 +1,5 @@
+gcc-features
+------------
+
+* The :manual:`Compile Features <cmake-compile-features(7)>` functionality
+  is now aware of the availability of C99 in gcc since version 3.4.
diff --git a/Modules/Compiler/GNU-C-FeatureTests.cmake b/Modules/Compiler/GNU-C-FeatureTests.cmake
index b3fe33f..0ab5265 100644
--- a/Modules/Compiler/GNU-C-FeatureTests.cmake
+++ b/Modules/Compiler/GNU-C-FeatureTests.cmake
@@ -1,5 +1,5 @@
 
-set(_cmake_oldestSupported "(__GNUC__ * 100 + __GNUC_MINOR__) >= 404")
+set(_cmake_oldestSupported "(__GNUC__ * 100 + __GNUC_MINOR__) >= 304")
 
 # GNU 4.7 correctly sets __STDC_VERSION__ to 201112L, but GNU 4.6 sets it
 # to 201000L.  As the former is strictly greater than the latter, test only
@@ -8,10 +8,10 @@ set(_cmake_oldestSupported "(__GNUC__ * 100 + __GNUC_MINOR__) >= 404")
 # to the distinction between __cplusplus and __GXX_EXPERIMENTAL_CXX0X__ tests.
 set(GNU46_C11 "(__GNUC__ * 100 + __GNUC_MINOR__) >= 406 && defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201000L")
 set(_cmake_feature_test_c_static_assert "${GNU46_C11}")
-# Since 4.4 at least:
-set(GNU44_C99 "(__GNUC__ * 100 + __GNUC_MINOR__) >= 404 && defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L")
-set(_cmake_feature_test_c_restrict "${GNU44_C99}")
-set(_cmake_feature_test_c_variadic_macros "${GNU44_C99}")
+# Since 3.4 at least:
+set(GNU34_C99 "(__GNUC__ * 100 + __GNUC_MINOR__) >= 304 && defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L")
+set(_cmake_feature_test_c_restrict "${GNU34_C99}")
+set(_cmake_feature_test_c_variadic_macros "${GNU34_C99}")
 
 set(GNU_C90 "${_cmake_oldestSupported}")
 set(_cmake_feature_test_c_function_prototypes "${GNU_C90}")
diff --git a/Modules/Compiler/GNU-C.cmake b/Modules/Compiler/GNU-C.cmake
index 05c3bb2..3f02618 100644
--- a/Modules/Compiler/GNU-C.cmake
+++ b/Modules/Compiler/GNU-C.cmake
@@ -4,12 +4,12 @@ __compiler_gnu(C)
 if (NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 4.5)
   set(CMAKE_C90_STANDARD_COMPILE_OPTION "-std=c90")
   set(CMAKE_C90_EXTENSION_COMPILE_OPTION "-std=gnu90")
-elseif (NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 4.4)
+elseif (NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 3.4)
   set(CMAKE_C90_STANDARD_COMPILE_OPTION "-std=c89")
   set(CMAKE_C90_EXTENSION_COMPILE_OPTION "-std=gnu89")
 endif()
 
-if (NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 4.4)
+if (NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 3.4)
   set(CMAKE_C99_STANDARD_COMPILE_OPTION "-std=c99")
   set(CMAKE_C99_EXTENSION_COMPILE_OPTION "-std=gnu99")
 endif()
@@ -22,7 +22,7 @@ elseif (NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 4.6)
   set(CMAKE_C11_EXTENSION_COMPILE_OPTION "-std=gnu1x")
 endif()
 
-if(NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 4.4)
+if(NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 3.4)
   if (NOT CMAKE_C_COMPILER_FORCED)
     if (NOT CMAKE_C_STANDARD_COMPUTED_DEFAULT)
       message(FATAL_ERROR "CMAKE_C_STANDARD_COMPUTED_DEFAULT should be set for ${CMAKE_C_COMPILER_ID} (${CMAKE_C_COMPILER}) version ${CMAKE_C_COMPILER_VERSION}")
@@ -38,10 +38,9 @@ if(NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 4.4)
   endif()
 endif()
 
-
 macro(cmake_record_c_compile_features)
   set(_result 0)
-  if (NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 4.4)
+  if (NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 3.4)
     if(_result EQUAL 0 AND CMAKE_C11_STANDARD_COMPILE_OPTION)
       _record_compiler_features_c(11)
     endif()
diff --git a/Modules/Compiler/GNU-CXX.cmake b/Modules/Compiler/GNU-CXX.cmake
index b04ea11..c007c98 100644
--- a/Modules/Compiler/GNU-CXX.cmake
+++ b/Modules/Compiler/GNU-CXX.cmake
@@ -6,7 +6,7 @@ if (WIN32)
     set(CMAKE_CXX_COMPILE_OPTIONS_VISIBILITY_INLINES_HIDDEN "-fno-keep-inline-dllexport")
   endif()
 else()
-  if(NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.2)
+  if(NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.0)
     set(CMAKE_CXX_COMPILE_OPTIONS_VISIBILITY_INLINES_HIDDEN "-fvisibility-inlines-hidden")
   endif()
 endif()
diff --git a/Tests/Module/WriteCompilerDetectionHeader/CMakeLists.txt b/Tests/Module/WriteCompilerDetectionHeader/CMakeLists.txt
index 7957ab8..2657aeb 100644
--- a/Tests/Module/WriteCompilerDetectionHeader/CMakeLists.txt
+++ b/Tests/Module/WriteCompilerDetectionHeader/CMakeLists.txt
@@ -20,6 +20,17 @@ write_compiler_detection_header(
     ${cxx_known_features} ${c_known_features}
 )
 
+write_compiler_detection_header(
+  FILE "${CMAKE_CURRENT_BINARY_DIR}/compiler_multi_files/multi_file_compiler_detection.h"
+  PREFIX MULTI
+  OUTPUT_FILES_VAR multi_files
+  OUTPUT_DIR "${CMAKE_CURRENT_BINARY_DIR}/compiler_multi_files/compiler_support"
+  COMPILERS GNU Clang AppleClang MSVC SunPro Intel
+  VERSION 3.1
+  FEATURES
+    ${cxx_known_features} ${c_known_features}
+)
+
 macro(set_defines target true_defs false_defs)
   set(defines)
   foreach(def ${true_defs})
@@ -57,7 +68,11 @@ if (CMAKE_C_COMPILE_FEATURES)
 
     add_executable(C_undefined c_undefined.c)
     set_property(TARGET C_undefined PROPERTY C_STANDARD 90)
-    target_compile_options(C_undefined PRIVATE -Werror=undef)
+    include(CheckCCompilerFlag)
+    check_c_compiler_flag(-Werror=undef use_error_undef)
+    if (use_error_undef)
+        target_compile_options(C_undefined PRIVATE -Werror=undef)
+    endif()
 
     add_executable(WriteCompilerDetectionHeader_C main.c)
     set_property(TARGET WriteCompilerDetectionHeader_C PROPERTY C_STANDARD 90)
@@ -116,17 +131,6 @@ add_executable(WriteCompilerDetectionHeader main.cpp)
 set_property(TARGET WriteCompilerDetectionHeader PROPERTY CXX_STANDARD 98)
 set_defines(WriteCompilerDetectionHeader "${true_defs}" "${false_defs}")
 
-write_compiler_detection_header(
-  FILE "${CMAKE_CURRENT_BINARY_DIR}/compiler_multi_files/multi_file_compiler_detection.h"
-  PREFIX MULTI
-  OUTPUT_FILES_VAR multi_files
-  OUTPUT_DIR "${CMAKE_CURRENT_BINARY_DIR}/compiler_multi_files/compiler_support"
-  COMPILERS GNU Clang AppleClang MSVC SunPro Intel
-  VERSION 3.1
-  FEATURES
-    ${cxx_known_features} ${c_known_features}
-)
-
 add_executable(multi_files multi_files.cpp)
 set_property(TARGET multi_files PROPERTY CXX_STANDARD 98)
 target_include_directories(multi_files PRIVATE ${CMAKE_CURRENT_BINARY_DIR}/compiler_multi_files)