[clang-tidy] Add --use-color command line option and UseColor option to control colors in diagnostics

This patch adds `--use-color` command line option and `UseColor` option to clang-tidy to control colors in diagnostics. With these options, users can force colorful output. This is useful when using clang-tidy with parallelization command line tools (like ninja and GNU parallel), as they often pipe clang-tidy's standard output and make the colors disappear.

Reviewed By: njames93

Differential Revision: https://reviews.llvm.org/D79477

clang-tools-extra/clang-tidy/ClangTidy.cpp

@@ -106,7 +106,8 @@ public:
               DiagPrinter),
         SourceMgr(Diags, Files), Context(Context), ApplyFixes(ApplyFixes),
         TotalFixes(0), AppliedFixes(0), WarningsAsErrors(0) {
-    DiagOpts->ShowColors = llvm::sys::Process::StandardOutHasColors();
+    DiagOpts->ShowColors = Context.getOptions().UseColor.getValueOr(
+        llvm::sys::Process::StandardOutHasColors());
     DiagPrinter->BeginSourceFile(LangOpts);
   }
 

clang-tools-extra/clang-tidy/ClangTidyOptions.cpp

@@ -96,6 +96,7 @@ template <> struct MappingTraits<ClangTidyOptions> {
     IO.mapOptional("ExtraArgs", Options.ExtraArgs);
     IO.mapOptional("ExtraArgsBefore", Options.ExtraArgsBefore);
     IO.mapOptional("InheritParentConfig", Options.InheritParentConfig);
+    IO.mapOptional("UseColor", Options.UseColor);
   }
 };
 
@@ -154,6 +155,7 @@ ClangTidyOptions ClangTidyOptions::mergeWith(const ClangTidyOptions &Other,
   overrideValue(Result.SystemHeaders, Other.SystemHeaders);
   overrideValue(Result.FormatStyle, Other.FormatStyle);
   overrideValue(Result.User, Other.User);
+  overrideValue(Result.UseColor, Other.UseColor);
   mergeVectors(Result.ExtraArgs, Other.ExtraArgs);
   mergeVectors(Result.ExtraArgsBefore, Other.ExtraArgsBefore);
 

clang-tools-extra/clang-tidy/ClangTidyOptions.h

@@ -126,6 +126,9 @@ struct ClangTidyOptions {
   /// apply this config file on top of the parent one. If false or missing,
   /// only this configuration file will be used.
   llvm::Optional<bool> InheritParentConfig;
+
+  /// Use colors in diagnostics. If missing, it will be auto detected.
+  llvm::Optional<bool> UseColor;
 };
 
 /// Abstract interface for retrieving various ClangTidy options.

clang-tools-extra/clang-tidy/tool/ClangTidyMain.cpp

@@ -230,6 +230,15 @@ over the real file system.
                                        cl::value_desc("filename"),
                                        cl::cat(ClangTidyCategory));
 
+static cl::opt<bool> UseColor("use-color", cl::desc(R"(
+Use colors in diagnostics. If not set, colors
+will be used if the terminal connected to
+standard output supports colors.
+This option overrides the 'UseColor' option in
+.clang-tidy file, if any.
+)"),
+                              cl::init(false), cl::cat(ClangTidyCategory));
+
 namespace clang {
 namespace tidy {
 
@@ -292,6 +301,8 @@ static std::unique_ptr<ClangTidyOptionsProvider> createOptionsProvider(
     OverrideOptions.SystemHeaders = SystemHeaders;
   if (FormatStyle.getNumOccurrences() > 0)
     OverrideOptions.FormatStyle = FormatStyle;
+  if (UseColor.getNumOccurrences() > 0)
+    OverrideOptions.UseColor = UseColor;
 
   if (!Config.empty()) {
     if (llvm::ErrorOr<ClangTidyOptions> ParsedConfig =

clang-tools-extra/test/clang-tidy/infrastructure/use-color.cpp

@@ -0,0 +1,28 @@
+// RUN: clang-tidy -dump-config | FileCheck %s
+// RUN: clang-tidy -dump-config -use-color | FileCheck -check-prefix=CHECK-CONFIG-COLOR %s
+// RUN: clang-tidy -dump-config -use-color=false | FileCheck -check-prefix=CHECK-CONFIG-NO-COLOR %s
+// RUN: clang-tidy -config='UseColor: true' -dump-config | FileCheck -check-prefix=CHECK-CONFIG-COLOR %s
+// RUN: clang-tidy -config='UseColor: false' -dump-config | FileCheck -check-prefix=CHECK-CONFIG-NO-COLOR %s
+// RUN: clang-tidy -help | FileCheck -check-prefix=CHECK-OPT-PRESENT %s
+
+// REQUIRES: ansi-escape-sequences
+// RUN: clang-tidy -checks='-*, modernize-use-override' -extra-arg=-std=c++11 -use-color=false %s | FileCheck -check-prefix=CHECK-NO-COLOR %s
+// RUN: clang-tidy -checks='-*, modernize-use-override' -extra-arg=-std=c++11 %s | FileCheck -check-prefix=CHECK-NO-COLOR %s
+// RUN: clang-tidy -checks='-*, modernize-use-override' -extra-arg=-std=c++11 -use-color %s | FileCheck -check-prefix=CHECK-COLOR %s
+
+// CHECK-NOT: UseColor
+// CHECK-CONFIG-NO-COLOR: UseColor: false
+// CHECK-CONFIG-COLOR: UseColor: true
+// CHECK-OPT-PRESENT: --use-color
+
+class Base {
+public:
+  virtual ~Base() = 0;
+};
+
+class Delivered : public Base {
+public:
+  virtual ~Delivered() = default;
+  // CHECK-NO-COLOR: warning: prefer using 'override' or (rarely) 'final' instead of 'virtual' [modernize-use-override]
+  // CHECK-COLOR: {{.\[0;1;35m}}warning: {{.\[0m}}{{.\[1m}}prefer using 'override' or (rarely) 'final' instead of 'virtual' [modernize-use-override]
+};

clang-tools-extra/unittests/clang-tidy/ClangTidyOptionsTest.cpp

@@ -76,6 +76,7 @@ TEST(ParseConfiguration, MergeConfigurations) {
       User: user1
       ExtraArgs: ['arg1', 'arg2']
       ExtraArgsBefore: ['arg-before1', 'arg-before2']
+      UseColor: false
   )");
   ASSERT_TRUE(!!Options1);
   llvm::ErrorOr<ClangTidyOptions> Options2 = parseConfiguration(R"(
@@ -85,6 +86,7 @@ TEST(ParseConfiguration, MergeConfigurations) {
       User: user2
       ExtraArgs: ['arg3', 'arg4']
       ExtraArgsBefore: ['arg-before3', 'arg-before4']
+      UseColor: true
   )");
   ASSERT_TRUE(!!Options2);
   ClangTidyOptions Options = Options1->mergeWith(*Options2, 0);
@@ -98,6 +100,8 @@ TEST(ParseConfiguration, MergeConfigurations) {
   EXPECT_EQ("arg-before1,arg-before2,arg-before3,arg-before4",
             llvm::join(Options.ExtraArgsBefore->begin(),
                        Options.ExtraArgsBefore->end(), ","));
+  ASSERT_TRUE(Options.UseColor.hasValue());
+  EXPECT_TRUE(*Options.UseColor);
 }
 
 class TestCheck : public ClangTidyCheck {