Fix a crash-on-valid where a block capture copy expression was
picking up cleanups from earlier in the statement.  Also fix a
crash-on-invalid where a reference to an invalid decl from an
enclosing scope was causing an expression to fail to build, but
only *after* a cleanup was registered from that statement,
causing an assertion downstream.

The crash-on-valid is rdar://13459289.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177692 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index dd8dad3..52ed28a 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -10288,6 +10288,9 @@
 
   if (!Invalid && !ExDeclType->isDependentType()) {
     if (const RecordType *recordType = ExDeclType->getAs<RecordType>()) {
+      // Insulate this from anything else we might currently be parsing.
+      EnterExpressionEvaluationContext scope(*this, PotentiallyEvaluated);
+
       // C++ [except.handle]p16:
       //   The object declared in an exception-declaration or, if the 
       //   exception-declaration does not specify a name, a temporary (12.2) is