project: Add infrastructure for recording CXX compiler features

Add a feature test using the compiler macros and the preprocessor to
determine available features.

Add a CMAKE_CXX_COMPILE_FEATURES variable which contains all features
known to the loaded compiler, and a CMAKE_CXX_KNOWN_FEATURES variable
containing all features known to CMake.  Add language standard specific
variables for internal use to determine the standard-specific compile
flags to use.

This will be extended to other languages in the future.  Follow-up
commits will add features which will be recorded by the feature test.

1 files changed, 3 insertions, 0 deletions

diff --git a/Modules/CMakeCXXCompiler.cmake.in b/Modules/CMakeCXXCompiler.cmake.in
index c75611a..fdee336 100644
--- a/Modules/CMakeCXXCompiler.cmake.in
+++ b/Modules/CMakeCXXCompiler.cmake.in
@@ -2,6 +2,9 @@ set(CMAKE_CXX_COMPILER "@CMAKE_CXX_COMPILER@")
 set(CMAKE_CXX_COMPILER_ARG1 "@CMAKE_CXX_COMPILER_ARG1@")
 set(CMAKE_CXX_COMPILER_ID "@CMAKE_CXX_COMPILER_ID@")
 set(CMAKE_CXX_COMPILER_VERSION "@CMAKE_CXX_COMPILER_VERSION@")
+set(CMAKE_CXX_COMPILE_FEATURES "@CMAKE_CXX_COMPILE_FEATURES@")
+set(CMAKE_CXX11_COMPILE_FEATURES "@CMAKE_CXX11_COMPILE_FEATURES@")
+
 set(CMAKE_CXX_PLATFORM_ID "@CMAKE_CXX_PLATFORM_ID@")
 set(CMAKE_CXX_SIMULATE_ID "@CMAKE_CXX_SIMULATE_ID@")
 set(CMAKE_CXX_SIMULATE_VERSION "@CMAKE_CXX_SIMULATE_VERSION@")