r305561 - Fix a bug that warnings generated with -M or -MM flags

[Yuka Takahashi via cfe-commits]

Author: yamaguchi
Date: Fri Jun 16 11:01:13 2017
New Revision: 305561

URL: http://llvm.org/viewvc/llvm-project?rev=305561&view=rev
Log:
Fix a bug that warnings generated with -M or -MM flags

This is a patch for bug: https://bugs.llvm.org/show_bug.cgi?id=6817

Warnings should not be emitted with -M and -MM flags, because this mode
is only used for generate MakeFiles.

Modified:
    cfe/trunk/lib/Driver/ToolChains/Clang.cpp
    cfe/trunk/test/Driver/m_and_mm.c

Modified: cfe/trunk/lib/Driver/ToolChains/Clang.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Driver/ToolChains/Clang.cpp?rev=305561&r1=305560&r2=305561&view=diff
==============================================================================
--- cfe/trunk/lib/Driver/ToolChains/Clang.cpp (original)
+++ cfe/trunk/lib/Driver/ToolChains/Clang.cpp Fri Jun 16 11:01:13 2017
@@ -980,6 +980,9 @@ void Clang::AddPreprocessingOptions(Comp
         DepTarget = Args.MakeArgString(llvm::sys::path::filename(P));
       }
 
+      if (!A->getOption().matches(options::OPT_MD) && !A->getOption().matches(options::OPT_MMD)) {
+        CmdArgs.push_back("-w");
+      }
       CmdArgs.push_back("-MT");
       SmallString<128> Quoted;
       QuoteTarget(DepTarget, Quoted);

Modified: cfe/trunk/test/Driver/m_and_mm.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Driver/m_and_mm.c?rev=305561&r1=305560&r2=305561&view=diff
==============================================================================
--- cfe/trunk/test/Driver/m_and_mm.c (original)
+++ cfe/trunk/test/Driver/m_and_mm.c Fri Jun 16 11:01:13 2017
@@ -1,3 +1,15 @@
 // RUN: %clang -### \
 // RUN:   -M -MM %s 2> %t
 // RUN: not grep '"-sys-header-deps"' %t
+
+// RUN: %clang -M -MM %s 2> %t
+// RUN: not grep "warning" %t
+
+// RUN: %clang -MMD -MD %s 2> %t
+// RUN: grep "warning" %t
+
+#warning "This warning shouldn't show up with -M and -MM"
+int main (void)
+{
+    return 0;
+}