Add regression test for #10475 (#3468)

test/testunusedfunctions.cpp

@@ -46,6 +46,7 @@ private:
         TEST_CASE(template3);
         TEST_CASE(template4); // #9805
         TEST_CASE(template5);
+        TEST_CASE(template6); // #10475 crash
         TEST_CASE(throwIsNotAFunction);
         TEST_CASE(unusedError);
         TEST_CASE(unusedMain);
@@ -261,6 +262,12 @@ private:
         ASSERT_EQUALS("", errout.str());
     }
 
+    void template6() { // #10475
+        check("template<template<typename...> class Ref, typename... Args>\n"
+              "struct Foo<Ref<Args...>, Ref> : std::true_type {};\n");
+        ASSERT_EQUALS("", errout.str());
+    }
+
     void throwIsNotAFunction() {
         check("struct A {void f() const throw () {}}; int main() {A a; a.f();}");
         ASSERT_EQUALS("", errout.str());