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

clang/include/clang/Basic/DiagnosticOptions.def

@@ -72,6 +72,7 @@ DIAGOPT(VerifyDiagnostics, 1, 0) /// Check that diagnostics match the expected
 
 DIAGOPT(ElideType, 1, 0)         /// Elide identical types in template diffing
 DIAGOPT(ShowTemplateTree, 1, 0)  /// Print a template tree when diffing
+DIAGOPT(CLFallbackMode, 1, 0)    /// Format for clang-cl fallback mode
 
 VALUE_DIAGOPT(ErrorLimit, 32, 0)           /// Limit # errors emitted.
 /// Limit depth of macro expansion backtrace.

clang/include/clang/Frontend/TextDiagnostic.h

@@ -51,7 +51,8 @@ public:
   /// TextDiagnostic logic requires.
   static void printDiagnosticLevel(raw_ostream &OS,
                                    DiagnosticsEngine::Level Level,
-                                   bool ShowColors);
+                                   bool ShowColors,
+                                   bool CLFallbackMode = false);
 
   /// \brief Pretty-print a diagnostic message to a raw_ostream.
   ///

clang/lib/Driver/Tools.cpp

@@ -3783,6 +3783,9 @@ void Clang::AddClangCLArgs(const ArgList &Args, ArgStringList &CmdArgs) const {
 
   if (!Args.hasArg(options::OPT_fdiagnostics_format_EQ)) {
     CmdArgs.push_back("-fdiagnostics-format");
+    if (Args.hasArg(options::OPT__SLASH_fallback))
+      CmdArgs.push_back("msvc-fallback");
+    else
       CmdArgs.push_back("msvc");
   }
 }

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;

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();
 }

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,

clang/test/Driver/cl-fallback.c

@@ -6,6 +6,7 @@
 
 // RUN: %clang_cl /fallback /Dfoo=bar /Ubaz /Ifoo /O0 /Ox /GR /GR- /LD /LDd \
 // RUN:     /MD /MDd /MTd /MT -### -- %s 2>&1 | FileCheck %s
+// CHECK: "-fdiagnostics-format" "msvc-fallback"
 // CHECK: ||
 // CHECK: cl.exe
 // CHECK: "/c"

clang/test/Misc/diag-format.c

@@ -12,7 +12,7 @@
 //
 // RUN: %clang -fsyntax-only -fno-show-column %s 2>&1 | FileCheck %s -check-prefix=NO_COLUMN
 //
-
+// RUN: not %clang -fsyntax-only -Werror -fdiagnostics-format=msvc-fallback %s 2>&1 | FileCheck %s -check-prefix=MSVC-FALLBACK
 
 
 
@@ -31,4 +31,5 @@
 // VI: {{.*}} +28:8: warning: extra tokens at end of #endif directive [-Wextra-tokens]
 // MSVC_ORIG: {{.*}}(28) : warning: extra tokens at end of #endif directive [-Wextra-tokens]
 // NO_COLUMN: {{.*}}:28: warning: extra tokens at end of #endif directive [-Wextra-tokens]
+// MSVC-FALLBACK: {{.*}}(28,7) : error(clang): extra tokens at end of #endif directive
 int x;