CMake: Set HOST_LINK_VERSION on Darwin (PR21268)

[hans]

Summary

The Autoconf build already does this, but it was never ported to CMake. The host linker version affects the flags that Clang pass to the linker, notably whether it passes -demangle or not.

[thakis]

Looks good as far as I can tell, thanks.

(Should there be some OS X-only test that checks if the frontend passes -demangle to the linker?)

[thakis]

r221844

CMakeLists.txt

if (LLVM_COMPILER_IS_GCC_COMPATIBLE)
   endif ()
 
   check_cxx_compiler_flag("-Werror -Wnested-anon-types" CXX_SUPPORTS_NO_NESTED_ANON_TYPES_FLAG)
   if( CXX_SUPPORTS_NO_NESTED_ANON_TYPES_FLAG )
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-nested-anon-types" )
   endif()
 endif ()
 
+# Determine HOST_LINK_VERSION on Darwin.
+set(HOST_LINK_VERSION)
+if (APPLE)
+  set(LD_V_OUTPUT)
+  execute_process(
+    COMMAND sh -c "${CMAKE_LINKER} -v 2>&1 | head -1"
+    RESULT_VARIABLE HAD_ERROR
+    OUTPUT_VARIABLE LD_V_OUTPUT
+  )
+  if (NOT HAD_ERROR)
+    if ("${LD_V_OUTPUT}" MATCHES ".*ld64.*")
+      string(REGEX REPLACE ".*ld64-([0-9.]*).*" "\\1" HOST_LINK_VERSION ${LD_V_OUTPUT})
+    else()
+      string(REGEX REPLACE "[^0-9]*([0-9.]*).*" "\\1" HOST_LINK_VERSION ${LD_V_OUTPUT})
+    endif()
+  else()
+    message(FATAL_ERROR "${CMAKE_LINKER} failed with status ${HAD_ERROR}")
+  endif()
+endif()
+
 configure_file(
   ${CLANG_SOURCE_DIR}/include/clang/Config/config.h.cmake
   ${CLANG_BINARY_DIR}/include/clang/Config/config.h)
 
 include(CMakeParseArguments)
 
 function(clang_tablegen)
   # Syntax:

include/clang/Config/config.h.cmake

 #define GCC_INSTALL_PREFIX "${GCC_INSTALL_PREFIX}"
 
 /* Define if we have libxml2 */
 #cmakedefine CLANG_HAVE_LIBXML ${CLANG_HAVE_LIBXML}
 
 /* The LLVM product name and version */
 #define BACKEND_PACKAGE_STRING "${BACKEND_PACKAGE_STRING}"
 
+/* Linker version detected at compile time. */
+#cmakedefine HOST_LINK_VERSION "${HOST_LINK_VERSION}"
+
 #endif

include/clang/Config/config.h.in

 /* This generated file is for internal use. Do not include it from headers. */
 
 #ifdef CONFIG_H
 #error config.h can only be included once
 #else
 #define CONFIG_H
 
 /* Bug report URL. */
 #undef BUG_REPORT_URL
 
 /* Relative directory for resource files */
 #undef CLANG_RESOURCE_DIR
 
 /* Directories clang will search for headers */
 #undef C_INCLUDE_DIRS
 
-/* Linker version detected at compile time. */
-#undef HOST_LINK_VERSION
-
 /* Default <path> to all compiler invocations for --sysroot=<path>. */
 #undef DEFAULT_SYSROOT
 
 /* Directory where gcc is installed. */
 #undef GCC_INSTALL_PREFIX
 
 /* Define if we have libxml2 */
 #undef CLANG_HAVE_LIBXML
 
 #undef PACKAGE_STRING
 
 /* The LLVM product name and version */
 #define BACKEND_PACKAGE_STRING PACKAGE_STRING
 
+/* Linker version detected at compile time. */
+#undef HOST_LINK_VERSION
+
 #endif