GNU C: record that C99 is available since at least 3.4

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:

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.

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}")

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()