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

3 files changed, 23 insertions, 8 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;
diff --git a/clang/lib/Frontend/TextDiagnostic.cpp b/clang/lib/Frontend/TextDiagnostic.cpp
index 691ca3493a0..a2dc9537bc0 100644
--- a/clang/lib/Frontend/TextDiagnostic.cpp
+++ b/clang/lib/Frontend/TextDiagnostic.cpp
@@ -693,7 +693,8 @@ TextDiagnostic::emitDiagnosticMessage(SourceLocation Loc,
   if (DiagOpts->ShowColors)
     OS.resetColor();
   
-  printDiagnosticLevel(OS, Level, DiagOpts->ShowColors);
+  printDiagnosticLevel(OS, Level, DiagOpts->ShowColors,
+                       DiagOpts->CLFallbackMode);
   printDiagnosticMessage(OS, Level, Message,
                          OS.tell() - StartOfLocationInfo,
                          DiagOpts->MessageLength, DiagOpts->ShowColors);
@@ -702,7 +703,8 @@ TextDiagnostic::emitDiagnosticMessage(SourceLocation Loc,
 /*static*/ void
 TextDiagnostic::printDiagnosticLevel(raw_ostream &OS,
                                      DiagnosticsEngine::Level Level,
-                                     bool ShowColors) {
+                                     bool ShowColors,
+                                     bool CLFallbackMode) {
   if (ShowColors) {
     // Print diagnostic category in bold and color
     switch (Level) {
@@ -718,12 +720,21 @@ TextDiagnostic::printDiagnosticLevel(raw_ostream &OS,
   switch (Level) {
   case DiagnosticsEngine::Ignored:
     llvm_unreachable("Invalid diagnostic type");
-  case DiagnosticsEngine::Note:    OS << "note: "; break;
-  case DiagnosticsEngine::Warning: OS << "warning: "; break;
-  case DiagnosticsEngine::Error:   OS << "error: "; break;
-  case DiagnosticsEngine::Fatal:   OS << "fatal error: "; break;
+  case DiagnosticsEngine::Note:    OS << "note"; break;
+  case DiagnosticsEngine::Warning: OS << "warning"; break;
+  case DiagnosticsEngine::Error:   OS << "error"; break;
+  case DiagnosticsEngine::Fatal:   OS << "fatal error"; break;
   }
 
+  // In clang-cl /fallback mode, print diagnostics as "error(clang):". This
+  // makes it more clear whether a message is coming from clang or cl.exe,
+  // and it prevents MSBuild from concluding that the build failed just because
+  // there is an "error:" in the output.
+  if (CLFallbackMode)
+    OS << "(clang)";
+
+  OS << ": ";
+
   if (ShowColors)
     OS.resetColor();
 }
diff --git a/clang/lib/Frontend/TextDiagnosticPrinter.cpp b/clang/lib/Frontend/TextDiagnosticPrinter.cpp
index c22798af60a..994a8f74ed4 100644
--- a/clang/lib/Frontend/TextDiagnosticPrinter.cpp
+++ b/clang/lib/Frontend/TextDiagnosticPrinter.cpp
@@ -132,7 +132,8 @@ void TextDiagnosticPrinter::HandleDiagnostic(DiagnosticsEngine::Level Level,
   // diagnostics in a context that lacks language options, a source manager, or
   // other infrastructure necessary when emitting more rich diagnostics.
   if (!Info.getLocation().isValid()) {
-    TextDiagnostic::printDiagnosticLevel(OS, Level, DiagOpts->ShowColors);
+    TextDiagnostic::printDiagnosticLevel(OS, Level, DiagOpts->ShowColors,
+                                         DiagOpts->CLFallbackMode);
     TextDiagnostic::printDiagnosticMessage(OS, Level, DiagMessageStream.str(),
                                            OS.tell() - StartOfLocationInfo,
                                            DiagOpts->MessageLength,