Add --suppress-system-warnings (on by default, use =0 to disable)

 - For investigating warnings in system headers / builtins.
 - Currently also enables the behavior that allows silent redefinition
   of types in system headers. Conceptually these are separate but I
   didn't feel it was worth two options (or changing LangOptions).

llvm-svn: 56163

1 files changed, 8 insertions, 0 deletions

diff --git a/clang/Driver/clang.cpp b/clang/Driver/clang.cpp
index ef12eaf2c26..0efe56a3507 100644
--- a/clang/Driver/clang.cpp
+++ b/clang/Driver/clang.cpp
@@ -520,6 +520,11 @@ ErrorOnExtensions("pedantic-errors",
                   llvm::cl::desc("Issue an error on uses of GCC extensions"));
 
 static llvm::cl::opt<bool>
+SuppressSystemWarnings("suppress-system-warnings",
+                     llvm::cl::desc("Issue an error on uses of GCC extensions"),
+                       llvm::cl::init(true));
+
+static llvm::cl::opt<bool>
 WarnUnusedMacros("Wunused_macros",
          llvm::cl::desc("Warn for unused macros in the main translation unit"));
 
@@ -547,6 +552,9 @@ static void InitializeDiagnostics(Diagnostic &Diags) {
   Diags.setWarnOnExtensions(WarnOnExtensions);
   Diags.setErrorOnExtensions(ErrorOnExtensions);
 
+  // Suppress warnings in system headers unless requested not to.
+  Diags.setSuppressSystemWarnings(SuppressSystemWarnings);
+
   // Silence the "macro is not used" warning unless requested.
   if (!WarnUnusedMacros)
     Diags.setDiagnosticMapping(diag::pp_macro_not_used, diag::MAP_IGNORE);