[Bug c++/67621] New: Syntax error for template function of template class

[physik3 at gmx dot net]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67621

            Bug ID: 67621
           Summary: Syntax error for template function of template class
           Product: gcc
           Version: 5.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: physik3 at gmx dot net
  Target Milestone: ---

Hey guys,

I think I have found a bug in the GCC C++ frontend.

I have a template class which provides a function with additional template
parameters. This works fine if the class is parameterized with a non-template
type or a template type whose arguments are fixed, but the compiler throws a
syntax error if the class is parameterized with a template class itself whose
argument is open.

I could downsize the problem to the following minimal example:
============
template<typename F>
struct Foo {

        template<typename T> void foo(void) {}

};

template<typename B>
struct Bar {

};

int main(void) {
        Foo<double> foo1;
        foo1.foo<int>(); // this line works
        Foo<Bar<double>> foo2;
        foo2.foo<int>(); // this line works
        return 0;
}

template<typename B>
void baz(void) {
        Foo<Bar<B>> foo;
        foo.foo<int>(); // this line gives a compiler error
}
============

GCC quits with "error: expected ‘;’ before ‘int’". Because I cannot see any
syntactical error, I guess it is a bug in GCC. Moreover, the Visual Studio
compiler accepts this code.

I detected this working with version 4.8.3, but I verified that it also affects
the newer 5.2.1 release.

Best