Rationalize the last bit of "arbitrary" state that is carried between

diagnostics to control suppression of redundant information. It now
follows the same model as all the other state, and has a bit more clear
semantics.

This is making the duality of the state a bit annoying, and I've added
a FIXME to resolve it. The problem is that I need to lift the
TextDiagnostic up into an externally visible layer before that can
happen.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@142083 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/Frontend/TextDiagnosticPrinter.h

@@ -29,7 +29,7 @@ class TextDiagnosticPrinter : public DiagnosticConsumer {
 
   FullSourceLoc LastLoc;
   FullSourceLoc LastIncludeLoc;
-  unsigned LastCaretDiagnosticWasNote : 1;
+  DiagnosticsEngine::Level LastLevel;
   unsigned OwnsOutputStream : 1;
 
   /// A string to prefix to error messages.

lib/Frontend/TextDiagnosticPrinter.cpp

@@ -43,8 +43,7 @@ const unsigned WordWrapIndentation = 6;
 TextDiagnosticPrinter::TextDiagnosticPrinter(raw_ostream &os,
                                              const DiagnosticOptions &diags,
                                              bool _OwnsOutputStream)
-  : OS(os), LangOpts(0), DiagOpts(&diags),
-    LastCaretDiagnosticWasNote(0),
+  : OS(os), LangOpts(0), DiagOpts(&diags), LastLevel(),
     OwnsOutputStream(_OwnsOutputStream) {
 }
 
@@ -498,15 +497,23 @@ class TextDiagnostic {
   /// root locations rather than diagnostic locations.
   SourceLocation LastIncludeLoc;
 
+  /// \brief The level of the last diagnostic emitted.
+  ///
+  /// The level of the last diagnostic emitted. Used to detect level changes
+  /// which change the amount of information displayed.
+  DiagnosticsEngine::Level LastLevel;
+
 public:
   TextDiagnostic(raw_ostream &OS,
                  const SourceManager &SM,
                  const LangOptions &LangOpts,
                  const DiagnosticOptions &DiagOpts,
                  FullSourceLoc LastLoc = FullSourceLoc(),
-                 FullSourceLoc LastIncludeLoc = FullSourceLoc())
+                 FullSourceLoc LastIncludeLoc = FullSourceLoc(),
+                 DiagnosticsEngine::Level LastLevel
+                   = DiagnosticsEngine::Level())
     : OS(OS), SM(SM), LangOpts(LangOpts), DiagOpts(DiagOpts),
-      LastLoc(LastLoc), LastIncludeLoc(LastIncludeLoc) {
+      LastLoc(LastLoc), LastIncludeLoc(LastIncludeLoc), LastLevel(LastLevel) {
     if (LastLoc.isValid() && &SM != &LastLoc.getManager())
       this->LastLoc = SourceLocation();
     if (LastIncludeLoc.isValid() && &SM != &LastIncludeLoc.getManager())
@@ -519,6 +526,9 @@ public:
   /// \brief Get the last emitted include stack location.
   SourceLocation getLastIncludeLoc() const { return LastIncludeLoc; }
 
+  /// \brief Get the last diagnostic level.
+  DiagnosticsEngine::Level getLastLevel() const { return LastLevel; }
+
   void Emit(SourceLocation Loc, DiagnosticsEngine::Level Level,
             StringRef Message, ArrayRef<CharSourceRange> Ranges,
             ArrayRef<FixItHint> FixItHints,
@@ -550,7 +560,7 @@ public:
     // multiple times if one loc has multiple diagnostics.
     if (DiagOpts.ShowCarets &&
         (Loc != LastLoc || !Ranges.empty() || !FixItHints.empty() ||
-         (LastCaretDiagnosticWasNote && Level != DiagnosticsEngine::Note))) {
+         (LastLevel == DiagnosticsEngine::Note && Level != LastLevel))) {
       // Get the ranges into a local array we can hack on.
       SmallVector<CharSourceRange, 20> MutableRanges(Ranges.begin(),
                                                      Ranges.end());
@@ -566,6 +576,7 @@ public:
     }
 
     LastLoc = Loc;
+    LastLevel = Level;
   }
 
   /// \brief Emit the caret and underlining text.
@@ -1279,18 +1290,21 @@ void TextDiagnosticPrinter::HandleDiagnostic(DiagnosticsEngine::Level Level,
          "Unexpected diagnostic with no source manager");
   const SourceManager &SM = Info.getSourceManager();
   TextDiagnostic TextDiag(OS, SM, *LangOpts, *DiagOpts,
-                          LastLoc, LastIncludeLoc);
+                          LastLoc, LastIncludeLoc, LastLevel);
 
   TextDiag.Emit(Info.getLocation(), Level, DiagMessageStream.str(),
                 Info.getRanges(),
                 llvm::makeArrayRef(Info.getFixItHints(),
-                                   Info.getNumFixItHints()),
-                LastCaretDiagnosticWasNote);
+                                   Info.getNumFixItHints()));
 
   // Cache the LastLoc from the TextDiagnostic printing.
+  // FIXME: Rather than this, we should persist a TextDiagnostic object across
+  // diagnostics until the SourceManager changes. That will allow the
+  // TextDiagnostic object to form a 'session' of output where we can
+  // reasonably collapse redundant information.
   LastLoc = FullSourceLoc(TextDiag.getLastLoc(), SM);
   LastIncludeLoc = FullSourceLoc(TextDiag.getLastIncludeLoc(), SM);
-  LastCaretDiagnosticWasNote = (Level == DiagnosticsEngine::Note);
+  LastLevel = TextDiag.getLastLevel();
 
   OS.flush();
 }