[PATCH] clang-cl: print errors as "err" when in /fallback mode

[Hans Wennborg]

Hi rnk,

This works around the problem that MSBuild determines that a compilation is unsuccessful if it finds error messages in the output, regardless of exit code.

With the fallback mechanism, we want the build to succeed in the case where clang errors out, but the fallback succeeds. By printing the error messages slightly differently in this mode, we trick MSBuild into not thinking the build failed.

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

Files:
  include/clang/Basic/DiagnosticOptions.def
  include/clang/Frontend/TextDiagnostic.h
  lib/Driver/Tools.cpp
  lib/Frontend/CompilerInvocation.cpp
  lib/Frontend/TextDiagnostic.cpp
  lib/Frontend/TextDiagnosticPrinter.cpp
  test/Driver/cl-fallback.c
  test/Misc/diag-format.c

Index: include/clang/Basic/DiagnosticOptions.def
===================================================================
--- include/clang/Basic/DiagnosticOptions.def
+++ include/clang/Basic/DiagnosticOptions.def
@@ -72,6 +72,7 @@
 
 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.
Index: include/clang/Frontend/TextDiagnostic.h
===================================================================
--- include/clang/Frontend/TextDiagnostic.h
+++ include/clang/Frontend/TextDiagnostic.h
@@ -51,7 +51,8 @@
   /// 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.
   ///
Index: lib/Driver/Tools.cpp
===================================================================
--- lib/Driver/Tools.cpp
+++ lib/Driver/Tools.cpp
@@ -3783,7 +3783,10 @@
 
   if (!Args.hasArg(options::OPT_fdiagnostics_format_EQ)) {
     CmdArgs.push_back("-fdiagnostics-format");
-    CmdArgs.push_back("msvc");
+    if (Args.hasArg(options::OPT__SLASH_fallback))
+      CmdArgs.push_back("msvc-fallback");
+    else
+      CmdArgs.push_back("msvc");
   }
 }
 
Index: lib/Frontend/CompilerInvocation.cpp
===================================================================
--- lib/Frontend/CompilerInvocation.cpp
+++ lib/Frontend/CompilerInvocation.cpp
@@ -589,7 +589,10 @@
     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;
Index: lib/Frontend/TextDiagnostic.cpp
===================================================================
--- lib/Frontend/TextDiagnostic.cpp
+++ lib/Frontend/TextDiagnostic.cpp
@@ -693,16 +693,18 @@
   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);
 }
 
 /*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) {
@@ -715,12 +717,20 @@
     }
   }
 
+  const char *ErrMsg = "error: ";
+
+  // In clang-cl /fallback mode, print errors as "err", to prevent MSBuild
+  // from concluding that the build failed by detecting error messages in
+  // the output.
+  if (CLFallbackMode)
+    ErrMsg = "err: ";
+
   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::Error:   OS << ErrMsg; break;
   case DiagnosticsEngine::Fatal:   OS << "fatal error: "; break;
   }
 
Index: lib/Frontend/TextDiagnosticPrinter.cpp
===================================================================
--- lib/Frontend/TextDiagnosticPrinter.cpp
+++ lib/Frontend/TextDiagnosticPrinter.cpp
@@ -132,7 +132,8 @@
   // 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,
Index: test/Driver/cl-fallback.c
===================================================================
--- test/Driver/cl-fallback.c
+++ 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"
Index: test/Misc/diag-format.c
===================================================================
--- test/Misc/diag-format.c
+++ 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) : err: extra tokens at end of #endif directive
 int x;
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