PR37680: fix faulty assertion condition.

When looking up a template name, we can find an overload set containing a
function template and an unresolved non-type using declaration.

llvm-svn: 334106

clang/lib/AST/ASTContext.cpp

@@ -7292,6 +7292,7 @@ ASTContext::getOverloadedTemplateName(UnresolvedSetIterator Begin,
   for (UnresolvedSetIterator I = Begin; I != End; ++I) {
     NamedDecl *D = *I;
     assert(isa<FunctionTemplateDecl>(D) ||
+           isa<UnresolvedUsingValueDecl>(D) ||
            (isa<UsingShadowDecl>(D) &&
             isa<FunctionTemplateDecl>(D->getUnderlyingDecl())));
     *Storage++ = D;

clang/test/SemaTemplate/dependent-names.cpp

@@ -447,3 +447,15 @@ namespace DependentUnresolvedUsingTemplate {
     xb.h(); // expected-note {{instantiation of}}
   }
 }
+
+namespace PR37680 {
+  template <class a> struct b : a {
+    using a::add;
+    template<int> int add() { return this->template add(0); }
+  };
+  struct a {
+    template<typename T = void> int add(...);
+    void add(int);
+  };
+  int f(b<a> ba) { return ba.add<0>(); }
+}