improve Wx GCC ABI check #142

Start checking the ABI version at -fabi-version=0, which is the default,
and if that succeeds don't set the flag at all.

This will allow the code to work properly if and when Wx removes the ABI
check alltogether.

src/wx/CMakeLists.txt

@@ -111,7 +111,7 @@ IF(CMAKE_COMPILER_IS_GNUCXX)
     INCLUDE(CheckCXXSourceRuns)
 
     UNSET(WX_ABI_MATCHES)
-    SET(WX_ABI_VERSION 1)
+    SET(WX_ABI_VERSION 0)
 
     SET(CURRENT_DEFS ${CMAKE_REQUIRED_DEFINITIONS})
     SET(CURRENT_LIBS ${CMAKE_REQUIRED_LIBRARIES})
@@ -149,7 +149,7 @@ wxIMPLEMENT_APP(MyApp);
     SET(CMAKE_REQUIRED_DEFINITIONS ${CURRENT_DEFS})
     SET(CMAKE_REQUIRED_LIBRARIES   ${CURRENT_LIBS})
 
-    IF(${${WX_ABI_VAR}})
+    IF(${${WX_ABI_VAR}} AND (NOT WX_ABI_VERSION EQUAL 0))
         # add C++ flags
         STRING(REGEX REPLACE "<FLAGS>" "<FLAGS> -fabi-version=${WX_ABI_VERSION} " CMAKE_CXX_COMPILE_OBJECT ${CMAKE_CXX_COMPILE_OBJECT})
         SET(CMAKE_CXX_LINK_EXECUTABLE "${CMAKE_CXX_LINK_EXECUTABLE} -fabi-version=${WX_ABI_VERSION}")