Fix CXX11ABI builds with clang++

The intention of the `WITH_CXX11ABI` option is to allow the user to control toggle whether to compile against the CXX11ABI in libstdc++  (and whether to download a few specific CXX11ABI compatible mason packages as well).

This option is important if you are building binaries (like the node binaries) and you want to support a platform that is older and does not have a recent enough libstdc++ to support the CXX11ABI (like ubuntu:precise, centos6, etc).

But this was broken for clang++ builds due to the use of `MAKE_COMPILER_IS_GNUCXX`. That was preventing the correct flags from being set when using clang++ effectively making the option useless and resulting in the build defaulting to whatever the libstdc++-dev headers default is on the system (which varies per linux distribution based on how libstdc++-dev is packaged).

This fixes the problem by ensuring that clang++ builds still support toggling control over this option.

Note: clang++ > 3.9 supports targeting both the new CXX11ABI in libstdc++ (with `-D_GLIBCXX_USE_CXX11_ABI=1`) and targeting the old one (with `-D_GLIBCXX_USE_CXX11_ABI=0`).

1 files changed, 2 insertions, 6 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8307191a3f..46aea73356 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -15,13 +15,9 @@ include(cmake/xcode.cmake)
 
 if(WITH_CXX11ABI)
     set(MASON_CXXABI_SUFFIX -cxx11abi)
-    if(CMAKE_COMPILER_IS_GNUCXX)
-        add_definitions(-D_GLIBCXX_USE_CXX11_ABI=1)
-    endif()
+    add_definitions(-D_GLIBCXX_USE_CXX11_ABI=1)
 else()
-    if(CMAKE_COMPILER_IS_GNUCXX)
-        add_definitions(-D_GLIBCXX_USE_CXX11_ABI=0)
-    endif()
+    add_definitions(-D_GLIBCXX_USE_CXX11_ABI=0)
 endif()
 
 if(WITH_OSMESA AND WITH_EGL)