[diagtool] Use `operator<<(Colors)` to print out colored output.

[ruiu]

Summary

r368131 introduced this new API to print out messages in colors.
If the colored output is disabled, operator<<(Colors) becomes nop.
No functionality change intended.

[MaskRay]

clang/tools/diagtool/TreeView.cpp

167

out.enable_colors(out.has_colors());

It looks the function hasColors is overengineered. out in these files can only be llvm::outs(). It doesn't have to check if llvm::errs() is connected to a terminal.

[JDevlieghere]

LGTM with Fangrui's comment addressed.

[ruiu]

clang/tools/diagtool/TreeView.cpp

167

Done. Thanks.

clang/tools/diagtool/TreeView.cpp

 
 static bool hasColors(const llvm::raw_ostream &out) {
   if (&out != &llvm::errs() && &out != &llvm::outs())
     return false;
   return llvm::errs().is_displayed() && llvm::outs().is_displayed();
 }
 
 class TreePrinter {
+  using Colors = llvm::raw_ostream::Colors;
+
 public:
   llvm::raw_ostream &out;
-  const bool ShowColors;
   bool Internal;
 
-  TreePrinter(llvm::raw_ostream &out)
-      : out(out), ShowColors(hasColors(out)), Internal(false) {}
-
-  void setColor(llvm::raw_ostream::Colors Color) {
-    if (ShowColors)
-      out << llvm::sys::Process::OutputColor(static_cast<char>(Color), false,
-                                             false);
-  }
-
-  void resetColor() {
-    if (ShowColors)
-      out << llvm::sys::Process::ResetColor();
-  }
+  TreePrinter(llvm::raw_ostream &out) : out(out), Internal(false) {}
 
   static bool isIgnored(unsigned DiagID) {
     // FIXME: This feels like a hack.
     static clang::DiagnosticsEngine Diags(new DiagnosticIDs,
                                           new DiagnosticOptions);
     return Diags.isIgnored(DiagID, SourceLocation());
   }
 
static bool enabledByDefault(const GroupRecord &Group) {
 
     return true;
   }
 
   void printGroup(const GroupRecord &Group, unsigned Indent = 0) {
     out.indent(Indent * 2);
 
     if (enabledByDefault(Group))
-      setColor(llvm::raw_ostream::GREEN);
+      out << Colors::GREEN;
     else
-      setColor(llvm::raw_ostream::YELLOW);
+      out << Colors::YELLOW;
 
-    out << "-W" << Group.getName() << "\n";
-    resetColor();
+    out << "-W" << Group.getName() << "\n" << Colors::RESET;
 
     ++Indent;
     for (const GroupRecord &GR : Group.subgroups()) {
       printGroup(GR, Indent);
     }
 
     if (Internal) {
       for (const DiagnosticRecord &DR : Group.diagnostics()) {
-        if (ShowColors && !isIgnored(DR.DiagID))
-          setColor(llvm::raw_ostream::GREEN);
+        if (!isIgnored(DR.DiagID))
+          out << Colors::GREEN;
         out.indent(Indent * 2);
-        out << DR.getName();
-        resetColor();
-        out << "\n";
+        out << DR.getName() << Colors::RESET << "\n";
       }
     }
   }
 
   int showGroup(StringRef RootGroup) {
     ArrayRef<GroupRecord> AllGroups = getDiagnosticGroups();
 
     if (RootGroup.size() > UINT16_MAX) {
for (unsigned i = 0, e = AllGroups.size(); i != e; ++i) {
       if (!NonRootGroupIDs.count(i))
         printGroup(AllGroups[i]);
     }
 
     return 0;
   }
 
   void showKey() {
-    if (ShowColors) {
-      out << '\n';
-      setColor(llvm::raw_ostream::GREEN);
-      out << "GREEN";
-      resetColor();
-      out << " = enabled by default\n\n";
-    }
+    out << '\n' << Colors::GREEN << "GREEN" << Colors::RESET
+        << " = enabled by default\n\n";
   }
 };
 
 static void printUsage() {
   llvm::errs() << "Usage: diagtool tree [--internal] [<diagnostic-group>]\n";
 }
 
 int TreeView::run(unsigned int argc, char **argv, llvm::raw_ostream &out) {
if (RootGroup == "everything")
       ShowAll = true;
     // FIXME: Handle other special warning flags, like -pedantic.
     break;
   default:
     printUsage();
     return -1;
   }
 
+  if (!hasColors(out))
+    out.enable_colors(false);
+
   TreePrinter TP(out);
   TP.Internal = Internal;
   TP.showKey();
   return ShowAll ? TP.showAll() : TP.showGroup(RootGroup);
 }