C++1y: Allow aggregates to have default initializers.

Add a CXXDefaultInitExpr, analogous to CXXDefaultArgExpr, and use it both in
CXXCtorInitializers and in InitListExprs to represent a default initializer.

There's an additional complication here: because the default initializer can
refer to the initialized object via its 'this' pointer, we need to make sure
that 'this' points to the right thing within the evaluation.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@179958 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/DeclCXX.cpp b/lib/AST/DeclCXX.cpp
index 2c7c4d3..ece8315 100644
--- a/lib/AST/DeclCXX.cpp
+++ b/lib/AST/DeclCXX.cpp
@@ -505,7 +505,7 @@
     // C++ [dcl.init.aggr]p1:
     //   An aggregate is an array or a class with no user-declared
     //   constructors [...].
-    // C++0x [dcl.init.aggr]p1:
+    // C++11 [dcl.init.aggr]p1:
     //   An aggregate is an array or a class with no user-provided
     //   constructors [...].
     if (getASTContext().getLangOpts().CPlusPlus11
@@ -690,7 +690,10 @@
       // C++11 [dcl.init.aggr]p1:
       //   An aggregate is a [...] class with [...] no
       //   brace-or-equal-initializers for non-static data members.
-      data().Aggregate = false;
+      //
+      // This rule was removed in C++1y.
+      if (!getASTContext().getLangOpts().CPlusPlus1y)
+        data().Aggregate = false;
 
       // C++11 [class]p10:
       //   A POD struct is [...] a trivial class.