Fix #13929 FP internalAstError with using declaration and template aliased type

Author: web-flow

lib/templatesimplifier.cpp

@@ -2099,7 +2099,7 @@ void TemplateSimplifier::expandTemplate(
                     Token * const beforeTypeToken = mTokenList.back();
                     bool pointerType = false;
                     const bool isVariadicTemplateArg = templateDeclaration.isVariadic() && itype + 1 == typeParametersInDeclaration.size();
-                    if (isVariadicTemplateArg && mTypesUsedInTemplateInstantiation.size() > 1 && !Token::simpleMatch(tok3->next(), "..."))
+                    if (isVariadicTemplateArg && mTypesUsedInTemplateInstantiation.size() > 1 && !Token::Match(tok3->next(), "...|<"))
                         continue;
                     if (isVariadicTemplateArg && Token::Match(tok3, "%name% ... %name%"))
                         tok3 = tok3->tokAt(2);

test/testsimplifytemplate.cpp

@@ -6334,6 +6334,20 @@ class TestSimplifyTemplate : public TestFixture {
                                 "} "
                                 "} ;";
         ASSERT_EQUALS(expected, tok(code));
+        
+        const char code2[] = "template <typename T>\n" // #13929
+                             "struct S {};\n"
+                             "template <typename T, template<typename...> typename C = S>\n"
+                             "struct A {\n"
+                             "    using x = C<T>;\n"
+                             "};\n"
+                             "A<int> a;\n";
+        const char expected2[] = "template < typename T > "
+                                 "struct S { } ; "
+                                 "struct A<int,S> ; "
+                                 "A<int,S> a ; "
+                                 "struct A<int,S> { } ;";
+        ASSERT_EQUALS(expected2, tok(code2));
     }
 
     void template_variable_1() {