CMake: Set HOST_LINK_VERSION on Darwin (PR21268)

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.

http://reviews.llvm.org/D6239

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@221844 91177308-0d34-0410-b5e6-96231b3b80d8

CMakeLists.txt

@@ -253,6 +253,26 @@ if (LLVM_COMPILER_IS_GCC_COMPATIBLE)
   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/clang/Config/config.h.cmake

@@ -26,4 +26,7 @@
 /* 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

@@ -14,9 +14,6 @@
 /* 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
 
@@ -31,4 +28,7 @@
 /* The LLVM product name and version */
 #define BACKEND_PACKAGE_STRING PACKAGE_STRING
 
+/* Linker version detected at compile time. */
+#undef HOST_LINK_VERSION
+
 #endif

test/Driver/darwin-ld-demangle.c

+// REQUIRES: system-darwin
+
+// On Darwin, -demangle is passed to the linker of HOST_LINK_VERSION
+// is high enough. It is assumed to be high enough on systems where
+// this test gets run.
+
+// RUN: %clang -### %s 2>&1 | FileCheck %s
+// CHECK: -demangle