clang-cl: print diagnostics as "error(clang): foo" in /fallback mode

This solves two problems:

1) MSBuild will not flag the build as unsuccessful just because we print
   an error in the output, since "error(clang):" doesn't seem to match
   the regex it's using.

2) It becomes more clear that the diagnostic is coming from clang as
   supposed to cl.exe.

Differential Revision: http://llvm-reviews.chandlerc.com/D1735

llvm-svn: 191250

1 files changed, 4 insertions, 1 deletions

diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 1c3dd7da7c5..b13507a5ef1 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -589,7 +589,10 @@ bool clang::ParseDiagnosticArgs(DiagnosticOptions &Opts, ArgList &Args,
     Opts.setFormat(DiagnosticOptions::Clang);
   else if (Format == "msvc")
     Opts.setFormat(DiagnosticOptions::Msvc);
-  else if (Format == "vi")
+  else if (Format == "msvc-fallback") {
+    Opts.setFormat(DiagnosticOptions::Msvc);
+    Opts.CLFallbackMode = true;
+  } else if (Format == "vi")
     Opts.setFormat(DiagnosticOptions::Vi);
   else {
     Success = false;