Update testfunctions.cpp

Author: chrchr-github

test/testfunctions.cpp

@@ -2220,6 +2220,12 @@ class TestFunctions : public TestFixture {
               "    return b;\n"
               "}\n", s);
         TODO_ASSERT_EQUALS("", "[test.cpp:6:5]: (debug) auto token with no type. [autoNoType]\n", errout_str());
+
+        check("template <typename T>\n" // #13509
+              "void f(const T& t) {\n"
+              "    t.g();\n"
+              "}\n", s);
+        ASSERT_EQUALS("", errout_str());
     }
 
     void checkUseStandardLibrary1() {