Introduce basic ASTs for lambda expressions. This covers:
  - Capturing variables by-reference and by-copy within a lambda
  - The representation of lambda captures
  - The creation of the non-static data members in the lambda class
  that store the captured variables
  - The initialization of the non-static data members from the
  captured variables
  - Pretty-printing lambda expressions

There are a number of FIXMEs, both explicit and implied, including:
  - Creating a field for a capture of 'this'
  - Improved diagnostics for initialization failures when capturing
  variables by copy
  - Dealing with temporaries created during said initialization
  - Template instantiation
  - AST (de-)serialization
  - Binding and returning the lambda expression; turning it into a
  proper temporary
  - Lots and lots of semantic constraints
  - Parameter pack captures


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@149977 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/TreeTransform.h b/lib/Sema/TreeTransform.h
index f011b1b..ca72bc7 100644
--- a/lib/Sema/TreeTransform.h
+++ b/lib/Sema/TreeTransform.h
@@ -7620,6 +7620,13 @@
 
 template<typename Derived>
 ExprResult
+TreeTransform<Derived>::TransformLambdaExpr(LambdaExpr *E) {
+  assert(false && "Lambda expressions cannot be instantiated (yet)");
+  return ExprError();
+}
+
+template<typename Derived>
+ExprResult
 TreeTransform<Derived>::TransformCXXUnresolvedConstructExpr(
                                                   CXXUnresolvedConstructExpr *E) {
   TypeSourceInfo *T = getDerived().TransformType(E->getTypeSourceInfo());