Fix compile failure with GCC 6 and 7baserock/5.6

Patch from https://trac.webkit.org/changeset/205672/webkit

Issue in WebKit: https://bugs.webkit.org/show_bug.cgi?id=161697

1 files changed, 27 insertions, 0 deletions

diff --git a/Source/cmake/OptionsCommon.cmake b/Source/cmake/OptionsCommon.cmake
index ee3ce7a49..4eab90de7 100644
--- a/Source/cmake/OptionsCommon.cmake
+++ b/Source/cmake/OptionsCommon.cmake
@@ -35,6 +35,33 @@ if (UNIX AND NOT APPLE)
     set(CMAKE_SHARED_LINKER_FLAGS "-Wl,--no-undefined ${CMAKE_SHARED_LINKER_FLAGS}")
 endif ()
 
+endif ()
+
+# Ensure that the default include system directories are added to the list of CMake implicit includes.
+# This workarounds an issue that happens when using GCC 6 and using system includes (-isystem).
+# For more details check: https://bugs.webkit.org/show_bug.cgi?id=161697
+macro(DETERMINE_GCC_SYSTEM_INCLUDE_DIRS _lang _compiler _flags _result)
+    file(WRITE "${CMAKE_BINARY_DIR}/CMakeFiles/dummy" "\n")
+    separate_arguments(_buildFlags UNIX_COMMAND "${_flags}")
+    execute_process(COMMAND ${_compiler} ${_buildFlags} -v -E -x ${_lang} -dD dummy
+                    WORKING_DIRECTORY ${CMAKE_BINARY_DIR}/CMakeFiles OUTPUT_QUIET
+                    ERROR_VARIABLE _gccOutput)
+    file(REMOVE "${CMAKE_BINARY_DIR}/CMakeFiles/dummy")
+    if ("${_gccOutput}" MATCHES "> search starts here[^\n]+\n *(.+) *\n *End of (search) list")
+        set(${_result} ${CMAKE_MATCH_1})
+        string(REPLACE "\n" " " ${_result} "${${_result}}")
+        separate_arguments(${_result})
+    endif ()
+endmacro()
+
+if (CMAKE_COMPILER_IS_GNUCC)
+   DETERMINE_GCC_SYSTEM_INCLUDE_DIRS("c" "${CMAKE_C_COMPILER}" "${CMAKE_C_FLAGS}" SYSTEM_INCLUDE_DIRS)
+   set(CMAKE_C_IMPLICIT_INCLUDE_DIRECTORIES ${CMAKE_C_IMPLICIT_INCLUDE_DIRECTORIES} ${SYSTEM_INCLUDE_DIRS})
+endif ()
+
+if (CMAKE_COMPILER_IS_GNUCXX)
+   DETERMINE_GCC_SYSTEM_INCLUDE_DIRS("c++" "${CMAKE_CXX_COMPILER}" "${CMAKE_CXX_FLAGS}" SYSTEM_INCLUDE_DIRS)
+   set(CMAKE_CXX_IMPLICIT_INCLUDE_DIRECTORIES ${CMAKE_CXX_IMPLICIT_INCLUDE_DIRECTORIES} ${SYSTEM_INCLUDE_DIRS})
 set(LIB_SUFFIX "" CACHE STRING "Define suffix of directory name (32/64)")
 
 set(LIB_INSTALL_DIR "lib${LIB_SUFFIX}" CACHE PATH "Where to install libraries (lib${LIB_SUFFIX})")