Add -ffreestanding to suppress the implicit declaration of library builtins like printf and malloc. Fixes PR3586

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@64566 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 11 insertions, 0 deletions

diff --git a/Driver/clang.cpp b/Driver/clang.cpp
index 1452a61a21..2f7ce69ee3 100644
--- a/Driver/clang.cpp
+++ b/Driver/clang.cpp
@@ -209,6 +209,14 @@ InheritanceViewCls("cxx-inheritance-view",
                   llvm::cl::desc("View C++ inheritance for a specified class"));
 
 //===----------------------------------------------------------------------===//
+// Builtin Options
+//===----------------------------------------------------------------------===//
+static llvm::cl::opt<bool>
+Freestanding("ffreestanding",
+             llvm::cl::desc("Assert that the compiler takes place in a "
+                            "freestanding environment"));
+
+//===----------------------------------------------------------------------===//
 // Analyzer Options.
 //===----------------------------------------------------------------------===//
 
@@ -636,6 +644,9 @@ static void InitializeLanguageStandard(LangOptions &Options, LangKind LK,
   if (EnableBlocks.getPosition())
     Options.Blocks = EnableBlocks;
 
+  if (Freestanding)
+    Options.Freestanding = 1;
+
   // Override the default runtime if the user requested it.
   if (NeXTRuntime)
     Options.NeXTRuntime = 1;