Introduce support for template instantiation of lambda
expressions. This is mostly a simple refact, splitting the main "start
a lambda expression" function into smaller chunks that are driven
either from the parser (Sema::ActOnLambdaExpr) or during AST
transformation (TreeTransform::TransformLambdaExpr). A few minor
interesting points:

  - Added new entry points for TreeTransform, so that we can
  explicitly establish the link between the lambda closure type in the
  template and the lambda closure type in the instantiation.
  - Added a bit into LambdaExpr specifying whether it had an explicit
  result type or not. We should have had this anyway.

This code is 'lightly' tested.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@150417 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaTemplate.cpp b/lib/Sema/SemaTemplate.cpp
index af2c6ef..17bdd69 100644
--- a/lib/Sema/SemaTemplate.cpp
+++ b/lib/Sema/SemaTemplate.cpp
@@ -6842,6 +6842,11 @@
       this->Loc = Loc;
       this->Entity = Entity;
     }
+      
+    ExprResult TransformLambdaExpr(LambdaExpr *E) {
+      // Lambdas never need to be transformed.
+      return E;
+    }
   };
 }