Add support in CMake to statically link the C++ standard library.

It is sometimes useful to have the C++ standard library linked into the
assembly when compiling clang, particularly when distributing a compiler
onto systems that don't have a copy of stdlibc++ or libc++ installed.

This functionality should work with either GCC or Clang as the host
compiler, though statically linking libc++ (as may be required for
licensing purposes) is only possible if the host compiler is Clang with
a copy of libc++ available.

Differential Revision: https://reviews.llvm.org/D65603

llvm-svn: 368907

1 files changed, 20 insertions, 0 deletions

diff --git a/llvm/cmake/modules/HandleLLVMStdlib.cmake b/llvm/cmake/modules/HandleLLVMStdlib.cmake
index f0e22d1a5b3..b67d87d4300 100644
--- a/llvm/cmake/modules/HandleLLVMStdlib.cmake
+++ b/llvm/cmake/modules/HandleLLVMStdlib.cmake
@@ -31,4 +31,24 @@ if(NOT DEFINED LLVM_STDLIB_HANDLED)
       message(WARNING "Not sure how to specify libc++ for this compiler")
     endif()
   endif()
+
+  if(LLVM_STATIC_LINK_CXX_STDLIB)
+    if(LLVM_COMPILER_IS_GCC_COMPATIBLE)
+      check_cxx_compiler_flag("-static-libstdc++"
+                              CXX_COMPILER_SUPPORTS_STATIC_STDLIB)
+      check_linker_flag("-static-libstdc++" CXX_LINKER_SUPPORTS_STATIC_STDLIB)
+      if(CXX_COMPILER_SUPPORTS_STATIC_STDLIB AND
+        CXX_LINKER_SUPPORTS_STATIC_STDLIB)
+        append("-static-libstdc++"
+          CMAKE_EXE_LINKER_FLAGS CMAKE_SHARED_LINKER_FLAGS
+          CMAKE_MODULE_LINKER_FLAGS)
+      else()
+        message(WARNING
+          "Can't specify static linking for the C++ standard library")
+      endif()
+    else()
+      message(WARNING "Not sure how to specify static linking of C++ standard "
+        "library for this compiler")
+    endif()
+  endif()
 endif()