Implement bracket insertion for Objective-C instance message sends as

part of parser recovery. For example, given:

  a method1:arg];

we detect after parsing the expression "a" that we have the start of a
message send expression. We pretend we've seen a '[' prior to the a,
then parse the remainder as a message send. We'll then give a
diagnostic+fix-it such as:

fixit-objc-message.m:17:3: error: missing '[' at start of message
      send expression
  a method1:arg];
  ^
  [

The algorithm here is very simple, and always assumes that the open
bracket goes at the beginning of the message send. It also only works
for non-super instance message sends at this time.

llvm-svn: 113968

1 files changed, 16 insertions, 0 deletions

diff --git a/clang/lib/Parse/RAIIObjectsForParser.h b/clang/lib/Parse/RAIIObjectsForParser.h
index addc7950839..583f18428d6 100644
--- a/clang/lib/Parse/RAIIObjectsForParser.h
+++ b/clang/lib/Parse/RAIIObjectsForParser.h
@@ -80,6 +80,22 @@ namespace clang {
     }
   };
   
+  class InMessageExpressionRAIIObject {
+    bool &InMessageExpression;
+    bool OldValue;
+    
+  public:
+    InMessageExpressionRAIIObject(Parser &P, bool Value)
+      : InMessageExpression(P.InMessageExpression), 
+        OldValue(P.InMessageExpression) {
+      InMessageExpression = Value;
+    }
+    
+    ~InMessageExpressionRAIIObject() {
+      InMessageExpression = OldValue;
+    }
+  };
+  
   /// \brief RAII object that makes sure paren/bracket/brace count is correct
   /// after declaration/statement parsing, even when there's a parsing error.
   class ParenBraceBracketBalancer {