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, 8 insertions, 0 deletions

diff --git a/clang/lib/Driver/ToolChain.cpp b/clang/lib/Driver/ToolChain.cpp
index 2be7f0f6900..b8dd37ca577 100644
--- a/clang/lib/Driver/ToolChain.cpp
+++ b/clang/lib/Driver/ToolChain.cpp
@@ -648,8 +648,16 @@ void ToolChain::AddClangCXXStdlibIncludeArgs(const ArgList &DriverArgs,
   DriverArgs.AddAllArgs(CC1Args, options::OPT_stdlib_EQ);
 }
 
+bool ToolChain::ShouldLinkCXXStdlib(const llvm::opt::ArgList &Args) const {
+  return getDriver().CCCIsCXX() &&
+         !Args.hasArg(options::OPT_nostdlib, options::OPT_nodefaultlibs,
+                      options::OPT_nostdlibxx);
+}
+
 void ToolChain::AddCXXStdlibLibArgs(const ArgList &Args,
                                     ArgStringList &CmdArgs) const {
+  assert(!Args.hasArg(options::OPT_nostdlibxx) &&
+         "should not have called this");
   CXXStdlibType Type = GetCXXStdlibType(Args);
 
   switch (Type) {