Implement Sebastian's idea for simplifying our handling of the greater-than operator/delimiter. Also, clean up after ourselves following a failed parse of a template-argument-list

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@64166 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/clang/Parse/Parser.h b/include/clang/Parse/Parser.h
index a197f2c..64b2f13 100644
--- a/include/clang/Parse/Parser.h
+++ b/include/clang/Parse/Parser.h
@@ -64,34 +64,18 @@
   /// argument list.
   bool GreaterThanIsOperator;
 
-  /// \brief RAII object that makes '>' behave like the closing angle
-  /// bracket for a template argument list.
-  struct MakeGreaterThanTemplateArgumentListTerminator {
+  /// \brief RAII object that makes '>' behave either as an operator
+  /// or as the closing angle bracket for a template argument list.
+  struct GreaterThanIsOperatorScope {
     bool &GreaterThanIsOperator;
     bool OldGreaterThanIsOperator;
    
-    MakeGreaterThanTemplateArgumentListTerminator(bool &GTIO)
+    GreaterThanIsOperatorScope(bool &GTIO, bool Val)
       : GreaterThanIsOperator(GTIO), OldGreaterThanIsOperator(GTIO) { 
-      GTIO = false;
+      GreaterThanIsOperator = Val;
     }
 
-    ~MakeGreaterThanTemplateArgumentListTerminator() {
-      GreaterThanIsOperator = OldGreaterThanIsOperator;
-    }
-  };
-
-  /// \brief RAII object that makes '>' behave like an
-  /// operator. Occurs, for example, inside parentheses.
-  struct MakeGreaterThanAnOperator {
-    bool &GreaterThanIsOperator;
-    bool OldGreaterThanIsOperator;
-   
-    MakeGreaterThanAnOperator(bool &GTIO)
-      : GreaterThanIsOperator(GTIO), OldGreaterThanIsOperator(GTIO) { 
-      GTIO = true;
-    }
-
-    ~MakeGreaterThanAnOperator() {
+    ~GreaterThanIsOperatorScope() {
       GreaterThanIsOperator = OldGreaterThanIsOperator;
     }
   };
diff --git a/lib/Parse/ParseExpr.cpp b/lib/Parse/ParseExpr.cpp
index 0f04d13..f7eeef7 100644
--- a/lib/Parse/ParseExpr.cpp
+++ b/lib/Parse/ParseExpr.cpp
@@ -1112,7 +1112,7 @@
 Parser::ParseParenExpression(ParenParseOption &ExprType,
                              TypeTy *&CastTy, SourceLocation &RParenLoc) {
   assert(Tok.is(tok::l_paren) && "Not a paren expr!");
-  MakeGreaterThanAnOperator G(GreaterThanIsOperator);
+  GreaterThanIsOperatorScope G(GreaterThanIsOperator, true);
   SourceLocation OpenLoc = ConsumeParen();
   OwningExprResult Result(Actions, true);
   CastTy = 0;
diff --git a/lib/Parse/ParseTemplate.cpp b/lib/Parse/ParseTemplate.cpp
index f083be5..fa76714 100644
--- a/lib/Parse/ParseTemplate.cpp
+++ b/lib/Parse/ParseTemplate.cpp
@@ -371,13 +371,17 @@
   TemplateArgList TemplateArgs;
   TemplateArgIsTypeList TemplateArgIsType;
   {
-    MakeGreaterThanTemplateArgumentListTerminator G(GreaterThanIsOperator);
+    GreaterThanIsOperatorScope G(GreaterThanIsOperator, false);
     if (Tok.isNot(tok::greater) && 
         ParseTemplateArgumentList(TemplateArgs, TemplateArgIsType)) {
       // Try to find the closing '>'.
       SkipUntil(tok::greater, true, true);
+
+      // Clean up any template arguments that we successfully parsed.
+      ASTTemplateArgsPtr TemplateArgsPtr(Actions, &TemplateArgs[0],
+                                         &TemplateArgIsType[0],
+                                         TemplateArgs.size());
       
-      // FIXME: What's our recovery strategy for failed template-argument-lists?
       return;
     }
   }