Features: Record for GNU 4.7.

Update the CompileFeatures test to verify that unsupported features
do not work.

Modules/Compiler/GNU-CXX-FeatureTests.cmake

@@ -1,7 +1,7 @@
 
 # Reference: http://gcc.gnu.org/projects/cxx0x.html
 
-set(_oldestSupported "(__GNUC__ * 100 + __GNUC_MINOR__) >= 408")
+set(_oldestSupported "(__GNUC__ * 100 + __GNUC_MINOR__) >= 407")
 # Introduced in GCC 4.8.1
 set(GNU481_CXX11 "((__GNUC__ * 100 + __GNUC_MINOR__) > 408 || __GNUC_PATCHLEVEL__ >= 1) && __cplusplus >= 201103L")
 set(_cmake_feature_test_cxx_decltype_incomplete_return_types "${GNU481_CXX11}")
@@ -12,8 +12,7 @@ set(_cmake_feature_test_cxx_alignof "${GNU48_CXX11}")
 set(_cmake_feature_test_cxx_attributes "${GNU48_CXX11}")
 set(_cmake_feature_test_cxx_inheriting_constructors "${GNU48_CXX11}")
 set(_cmake_feature_test_cxx_thread_local "${GNU48_CXX11}")
-# TODO: Should be supported by GNU 4.7
-set(GNU47_CXX11 "${_oldestSupported} && __cplusplus >= 201103L")
+set(GNU47_CXX11 "(__GNUC__ * 100 + __GNUC_MINOR__) >= 407 && __cplusplus >= 201103L")
 set(_cmake_feature_test_cxx_alias_templates "${GNU47_CXX11}")
 set(_cmake_feature_test_cxx_delegating_constructors "${GNU47_CXX11}")
 set(_cmake_feature_test_cxx_extended_friend_declarations "${GNU47_CXX11}")

Modules/Compiler/GNU-CXX.cmake

@@ -32,7 +32,7 @@ macro(cmake_record_cxx_compile_features)
     endif()
   endmacro()
 
-  if (UNIX AND NOT APPLE AND NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.8)
+  if (UNIX AND NOT APPLE AND NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.7)
     _get_gcc_features(c++11 CMAKE_CXX11_COMPILE_FEATURES)
     _get_gcc_features(c++98 CMAKE_CXX98_COMPILE_FEATURES)
   else()

Tests/CompileFeatures/CMakeLists.txt

@@ -11,22 +11,33 @@ if (NOT CMAKE_CXX_COMPILE_FEATURES)
   return()
 endif()
 
-macro(run_test feature)
-  if (";${CMAKE_CXX_COMPILE_FEATURES};" MATCHES ${feature})
-    add_library(test_${feature} OBJECT ${feature}.cpp)
+macro(run_test feature lang)
+  if (";${CMAKE_${lang}_COMPILE_FEATURES};" MATCHES ${feature})
+    add_library(test_${feature} OBJECT ${feature})
     set_property(TARGET test_${feature}
       PROPERTY COMPILE_FEATURES "${feature}"
     )
   else()
-    message("Not supported: ${feature}")
+    list(APPEND ${lang}_non_features ${feature})
   endif()
 endmacro()
 
-get_property(features GLOBAL PROPERTY CMAKE_CXX_KNOWN_FEATURES)
-foreach(feature ${features})
-  run_test(${feature})
+get_property(cxx_features GLOBAL PROPERTY CMAKE_CXX_KNOWN_FEATURES)
+foreach(feature ${cxx_features})
+  run_test(${feature} CXX)
 endforeach()
 
+if (CMAKE_CXX_COMPILE_FEATURES)
+  include(CheckCXXSourceCompiles)
+  foreach(feature ${CXX_non_features})
+    check_cxx_source_compiles("#include \"${CMAKE_CURRENT_SOURCE_DIR}/${feature}.cpp\"\nint main() { return 0; }\n" ${feature}_works)
+    if (${feature}_works)
+      message(SEND_ERROR
+        "Feature ${feature} expected not to work for ${CMAKE_CXX_COMPILER_ID}-${CMAKE_CXX_COMPILER_VERSION}.  Update the supported features or blacklist it.")
+    endif()
+  endforeach()
+endif()
+
 add_executable(CompileFeatures main.cpp)
 set_property(TARGET CompileFeatures
   PROPERTY COMPILE_FEATURES "cxx_auto_type"