Explicitly defaulted constructors cannot be used for default initialization.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@161088 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaInit.cpp b/lib/Sema/SemaInit.cpp
index cab7661..27d58b2 100644
--- a/lib/Sema/SemaInit.cpp
+++ b/lib/Sema/SemaInit.cpp
@@ -2906,7 +2906,7 @@
   //   user-provided default constructor.
   if (Kind.getKind() == InitializationKind::IK_Default &&
       Entity.getType().isConstQualified() &&
-      cast<CXXConstructorDecl>(Best->Function)->isImplicit()) {
+      !cast<CXXConstructorDecl>(Best->Function)->isUserProvided()) {
     Sequence.SetFailed(InitializationSequence::FK_DefaultInitOfConst);
     return;
   }