PR33318: Add missing full-expression checking to static_assert expression.

This fixes missing lambda-captures for variables referenced only inside a
static_assert (!), among other things.

llvm-svn: 304760
diff --git a/clang/lib/Parse/ParseDeclCXX.cpp b/clang/lib/Parse/ParseDeclCXX.cpp
index 4c117f5..1a4607a 100644
--- a/clang/lib/Parse/ParseDeclCXX.cpp
+++ b/clang/lib/Parse/ParseDeclCXX.cpp
@@ -840,7 +840,9 @@
     return nullptr;
   }
 
-  ExprResult AssertExpr(ParseConstantExpression());
+  EnterExpressionEvaluationContext ConstantEvaluated(
+      Actions, Sema::ExpressionEvaluationContext::ConstantEvaluated);
+  ExprResult AssertExpr(ParseConstantExpressionInExprEvalContext());
   if (AssertExpr.isInvalid()) {
     SkipMalformedDecl();
     return nullptr;