Introduce -nostdlib++ flag to disable linking the C++ standard library.

Projects that want to statically link their own C++ standard library currently
need to pass -nostdlib or -nodefaultlibs, which also disables linking of the
builtins library, -lm, and so on. Alternatively, they could use `clang` instead
of `clang++`, but that already disables implicit addition of -lm on some
toolchains.

Add a dedicated flag -nostdlib++ that disables just linking of libc++ /
libstdc++. This is analogous to -nostdinc++.

https://reviews.llvm.org/D35780

llvm-svn: 308997

1 files changed, 2 insertions, 3 deletions

diff --git a/clang/lib/Driver/ToolChains/BareMetal.cpp b/clang/lib/Driver/ToolChains/BareMetal.cpp
index 5dc6dfad927..529a2093cf7 100644
--- a/clang/lib/Driver/ToolChains/BareMetal.cpp
+++ b/clang/lib/Driver/ToolChains/BareMetal.cpp
@@ -192,10 +192,9 @@ void baremetal::Linker::ConstructJob(Compilation &C, const JobAction &JA,
                             options::OPT_e, options::OPT_s, options::OPT_t,
                             options::OPT_Z_Flag, options::OPT_r});
 
+  if (TC.ShouldLinkCXXStdlib(Args))
+    TC.AddCXXStdlibLibArgs(Args, CmdArgs);
   if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nodefaultlibs)) {
-    if (C.getDriver().CCCIsCXX())
-      TC.AddCXXStdlibLibArgs(Args, CmdArgs);
-
     CmdArgs.push_back("-lc");
     CmdArgs.push_back("-lm");