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.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@231559 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index a80214e1e663b61529c94b1dda72ca653f68f41d..3c6827af9d8aed794fdb72f3c9d914e2e1b3dd36 100644 (file)
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -7704,6 +7704,8 @@ void gnutools::Link::ConstructJob(Compilation &C, const JobAction &JA,
       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)) {

diff --git a/test/Driver/linux-ld.c b/test/Driver/linux-ld.c
index f2e6eda3ffb40a8a0cd70f8c2a44e0695cec83b4..a16c36ab3d517604c47bed1df1ac585fd0a699f9 100644 (file)
--- a/test/Driver/linux-ld.c
+++ b/test/Driver/linux-ld.c
@@ -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 \