Comment parsing: refactor handling of command markers in AST

* Use the term 'command marker', because the semantics of 'backslash' and 'at'
  commands are the same.  (Talking about 'at commands' makes them look like a
  special entity.)

* Sink the flag down into bitfields, reducing the size of AST nodes.

* Change the flag into an enum for clarity.  Boolean function parameters are
  not very clear.

* Add unittests for new tok::at_command tokens.

llvm-svn: 176461

1 files changed, 6 insertions, 4 deletions

diff --git a/clang/lib/AST/CommentLexer.cpp b/clang/lib/AST/CommentLexer.cpp
index 20180994177..1194520bf36 100644
--- a/clang/lib/AST/CommentLexer.cpp
+++ b/clang/lib/AST/CommentLexer.cpp
@@ -298,7 +298,11 @@ void Lexer::lexCommentText(Token &T) {
     switch(*TokenPtr) {
       case '\\':
       case '@': {
-        bool AtCommand = (*TokenPtr == '@');
+        // Commands that start with a backslash and commands that start with
+        // 'at' have equivalent semantics.  But we keep information about the
+        // exact syntax in AST for comments.
+        tok::TokenKind CommandKind =
+            (*TokenPtr == '@') ? tok::at_command : tok::backslash_command;
         TokenPtr++;
         if (TokenPtr == CommentEnd) {
           formTextToken(T, TokenPtr);
@@ -359,9 +363,7 @@ void Lexer::lexCommentText(Token &T) {
           setupAndLexVerbatimLine(T, TokenPtr, Info);
           return;
         }
-        formTokenWithChars(T, TokenPtr, 
-                           (AtCommand ? tok::at_command 
-                                      : tok::backslash_command));
+        formTokenWithChars(T, TokenPtr, CommandKind);
         T.setCommandID(Info->getID());
         return;
       }