cmake: Add doc comments in compiler_flags.cmake.
BUG=https://bugs.chromium.org/p/aomedia/issues/detail?id=76
Change-Id: Id4c31aeb4593c80cf6f0c40d2846ec52ba44c3bb
diff --git a/build/cmake/compiler_flags.cmake b/build/cmake/compiler_flags.cmake
index 55c8ce3..a3e9794 100644
--- a/build/cmake/compiler_flags.cmake
+++ b/build/cmake/compiler_flags.cmake
@@ -13,6 +13,13 @@
include(CheckCCompilerFlag)
include(CheckCXXCompilerFlag)
+# Strings used to cache failed C/CXX flags.
+set(AOM_FAILED_C_FLAGS)
+set(AOM_FAILED_CXX_FLAGS)
+
+# Checks C compiler for support of $c_flag. Adds $c_flag to $CMAKE_C_FLAGS when
+# the compile test passes. Caches $c_flag in $AOM_FAILED_C_FLAGS when the test
+# fails.
function (add_c_flag_if_supported c_flag)
unset(C_FLAG_FOUND CACHE)
string(FIND "${CMAKE_C_FLAGS}" "${c_flag}" C_FLAG_FOUND)
@@ -32,6 +39,9 @@
endif ()
endfunction ()
+# Checks C++ compiler for support of $cxx_flag. Adds $cxx_flag to
+# $CMAKE_CXX_FLAGS when the compile test passes. Caches $c_flag in
+# $AOM_FAILED_CXX_FLAGS when the test fails.
function (add_cxx_flag_if_supported cxx_flag)
unset(CXX_FLAG_FOUND CACHE)
string(FIND "${CMAKE_CXX_FLAGS}" "${cxx_flag}" CXX_FLAG_FOUND)
@@ -52,6 +62,8 @@
endif ()
endfunction ()
+# Convenience method for adding a flag to both the C and C++ compiler command
+# lines.
function (add_compiler_flag_if_supported flag)
add_c_flag_if_supported(${flag})
add_cxx_flag_if_supported(${flag})
