Sema: Provide a valid source location when instantiating templates based on a CXXDefaultArgExpr.

Fixes PR13758.

llvm-svn: 168521

clang/include/clang/AST/ExprCXX.h

@@ -795,6 +795,8 @@ public:
     return SourceRange();
   }
 
+  SourceLocation getExprLoc() const LLVM_READONLY { return Loc; }
+
   static bool classof(const Stmt *T) {
     return T->getStmtClass() == CXXDefaultArgExprClass;
   }

clang/lib/Sema/SemaOverload.cpp

@@ -2980,7 +2980,7 @@ IsUserDefinedConversion(Sema &S, Expr *From, QualType ToType,
          S.IsDerivedFrom(From->getType(), ToType)))
       ConstructorsOnly = true;
 
-    S.RequireCompleteType(From->getLocStart(), ToType, 0);
+    S.RequireCompleteType(From->getExprLoc(), ToType, 0);
     // RequireCompleteType may have returned true due to some invalid decl
     // during template instantiation, but ToType may be complete enough now
     // to try to recover.

clang/test/SemaTemplate/default-expr-arguments.cpp

@@ -303,3 +303,21 @@ namespace PR12581 {
   {
   }
 }
+
+namespace PR13758 {
+  template <typename T> struct move_from {
+    T invalid; // expected-error {{field has incomplete type 'void'}}
+  };
+  template <class K>
+  struct unordered_map {
+    explicit unordered_map(int n = 42);
+    unordered_map(move_from<K> other);
+  };
+  template<typename T>
+  void StripedHashTable() {
+    new unordered_map<void>(); // expected-note {{in instantiation of template class 'PR13758::move_from<void>' requested here}}
+  }
+  void tt() {
+    StripedHashTable<int>(); // expected-note {{in instantiation of function template specialization 'PR13758::StripedHashTable<int>' requested here}}
+  }
+}