r231559 - Much like we silence warnings about -flto in many cases to facilitate

[Chandler Carruth]

Author: chandlerc
Date: Sat Mar  7 04:01:29 2015
New Revision: 231559

URL: http://llvm.org/viewvc/llvm-project?rev=231559&view=rev
Log:
Much like we silence warnings about -flto in many cases to facilitate
simplicity in build systems, silence '-stdlib=libc++' when linking. Even
if we're not linking C++ code per-se, we may be passing this flag so
that when we are linking C++ code we pick up the desired standard
library. While most build systems already provide separate C and C++
compile flags, many conflate link flags. Sadly, CMake is among them
causing this warning in a libc++ selfhost.

Modified:
    cfe/trunk/lib/Driver/Tools.cpp
    cfe/trunk/test/Driver/linux-ld.c

Modified: cfe/trunk/lib/Driver/Tools.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Driver/Tools.cpp?rev=231559&r1=231558&r2=231559&view=diff
==============================================================================
--- cfe/trunk/lib/Driver/Tools.cpp (original)
+++ cfe/trunk/lib/Driver/Tools.cpp Sat Mar  7 04:01:29 2015
@@ -7704,6 +7704,8 @@ void gnutools::Link::ConstructJob(Compil
       CmdArgs.push_back("-Bdynamic");
     CmdArgs.push_back("-lm");
   }
+  // Silence warnings when linking C code with a C++ '-stdlib' argument.
+  Args.ClaimAllArgs(options::OPT_stdlib_EQ);
 
   if (!Args.hasArg(options::OPT_nostdlib)) {
     if (!Args.hasArg(options::OPT_nodefaultlibs)) {

Modified: cfe/trunk/test/Driver/linux-ld.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Driver/linux-ld.c?rev=231559&r1=231558&r2=231559&view=diff
==============================================================================
--- cfe/trunk/test/Driver/linux-ld.c (original)
+++ cfe/trunk/test/Driver/linux-ld.c Sat Mar  7 04:01:29 2015
@@ -417,6 +417,23 @@
 // CHECK-BASIC-LIBCXX-INSTALL: "--sysroot=[[SYSROOT]]"
 // CHECK-BASIC-LIBCXX-INSTALL: "-L[[SYSROOT]]/usr/bin/../lib"
 //
+// Test that we can use -stdlib=libc++ in a build system even when it
+// occasionally links C code instead of C++ code.
+// RUN: %clang -no-canonical-prefixes -x c %s -### -o %t.o 2>&1 \
+// RUN:     -target x86_64-unknown-linux-gnu \
+// RUN:     -stdlib=libc++ \
+// RUN:     -ccc-install-dir %S/Inputs/basic_linux_libcxx_tree/usr/bin \
+// RUN:     --gcc-toolchain="" \
+// RUN:     --sysroot=%S/Inputs/basic_linux_libcxx_tree \
+// RUN:   | FileCheck --check-prefix=CHECK-BASIC-LIBCXX-C-LINK %s
+// CHECK-BASIC-LIBCXX-C-LINK-NOT: warning:
+// CHECK-BASIC-LIBCXX-C-LINK: "{{[^"]*}}clang{{[^"]*}}" "-cc1"
+// CHECK-BASIC-LIBCXX-C-LINK: "-isysroot" "[[SYSROOT:[^"]+]]"
+// CHECK-BASIC-LIBCXX-C-LINK-NOT: "-internal-isystem" "[[SYSROOT]]/usr/bin/../include/c++/v1"
+// CHECK-BASIC-LIBCXX-C-LINK: "-internal-isystem" "[[SYSROOT]]/usr/local/include"
+// CHECK-BASIC-LIBCXX-C-LINK: "--sysroot=[[SYSROOT]]"
+// CHECK-BASIC-LIBCXX-C-LINK: "-L[[SYSROOT]]/usr/bin/../lib"
+//
 // Test a very broken version of multiarch that shipped in Ubuntu 11.04.
 // RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
 // RUN:     --target=i386-unknown-linux \