[clang] Use a formatted_raw_ostream in TextDiagnostic

clang/include/clang/Frontend/TextDiagnostic.h

@@ -16,10 +16,12 @@
 #define LLVM_CLANG_FRONTEND_TEXTDIAGNOSTIC_H
 
 #include "clang/Frontend/DiagnosticRenderer.h"
-#include "llvm/Support/raw_ostream.h"
+#include "llvm/Support/FormattedStream.h"
 
 namespace clang {
 
+using llvm::formatted_raw_ostream;
+
 /// Class to encapsulate the logic for formatting and printing a textual
 /// diagnostic message.
 ///
@@ -33,7 +35,7 @@ namespace clang {
 /// DiagnosticClient is implemented through this class as is diagnostic
 /// printing coming out of libclang.
 class TextDiagnostic : public DiagnosticRenderer {
-  raw_ostream &OS;
+  formatted_raw_ostream OS;
   const Preprocessor *PP;
 
 public:
@@ -47,7 +49,7 @@ class TextDiagnostic : public DiagnosticRenderer {
     unsigned End;
     enum llvm::raw_ostream::Colors Color;
     StyleRange(unsigned S, unsigned E, enum llvm::raw_ostream::Colors C)
-        : Start(S), End(E), Color(C){};
+        : Start(S), End(E), Color(C) {};
   };
 
   /// Print the diagonstic level to a raw_ostream.

clang/lib/Frontend/TextDiagnostic.cpp

@@ -17,7 +17,6 @@
 #include "llvm/Support/ConvertUTF.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/Locale.h"
-#include "llvm/Support/raw_ostream.h"
 #include <algorithm>
 #include <optional>
 
@@ -662,7 +661,7 @@ void TextDiagnostic::emitDiagnosticMessage(
     FullSourceLoc Loc, PresumedLoc PLoc, DiagnosticsEngine::Level Level,
     StringRef Message, ArrayRef<clang::CharSourceRange> Ranges,
     DiagOrStoredDiag D) {
-  uint64_t StartOfLocationInfo = OS.tell();
+  uint64_t StartOfLocationInfo = OS.getColumn();
 
   // Emit the location of this particular diagnostic.
   if (Loc.isValid())
@@ -675,8 +674,11 @@ void TextDiagnostic::emitDiagnosticMessage(
     printDiagnosticLevel(OS, Level, DiagOpts.ShowColors);
   printDiagnosticMessage(OS,
                          /*IsSupplemental*/ Level == DiagnosticsEngine::Note,
-                         Message, OS.tell() - StartOfLocationInfo,
+                         Message, OS.getColumn() - StartOfLocationInfo,
                          DiagOpts.MessageLength, DiagOpts.ShowColors);
+  // We use a formatted ostream, which does its own buffering. Flush here
+  // so we keep the proper order of output.
+  OS.flush();
 }
 
 /*static*/ void
@@ -1485,7 +1487,7 @@ void TextDiagnostic::emitSnippet(StringRef SourceLine,
       if (CharStyle != Styles.end()) {
         if (!CurrentColor ||
             (CurrentColor && *CurrentColor != CharStyle->Color)) {
-          OS.changeColor(CharStyle->Color, false);
+          OS.changeColor(CharStyle->Color);
           CurrentColor = CharStyle->Color;
         }
       } else if (CurrentColor) {

clang/test/Frontend/diag-wrap-colors.cpp

@@ -0,0 +1,6 @@
+// RUN: not %clang_cc1 %s -fmessage-length=50 -fcolor-diagnostics -fno-show-source-location -o - 2>&1 | FileCheck %s
+
+struct F {
+  float a : 10;
+};
+// CHECK: bit-field 'a' has non-integral type 'float'

llvm/include/llvm/Support/FormattedStream.h

@@ -180,7 +180,8 @@ class LLVM_ABI formatted_raw_ostream : public raw_ostream {
     return *this;
   }
 
-  raw_ostream &changeColor(enum Colors Color, bool Bold, bool BG) override {
+  raw_ostream &changeColor(enum Colors Color, bool Bold = false,
+                           bool BG = false) override {
     if (colors_enabled()) {
       DisableScanScope S(this);
       raw_ostream::changeColor(Color, Bold, BG);