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From: "csaba_22 at yahoo dot co.uk" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/110330] New: GCC does not diagnose ambiguous function
 introduced from base class
Date: Tue, 20 Jun 2023 22:28:26 +0000
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X-Bugzilla-Product: gcc
X-Bugzilla-Component: c++
X-Bugzilla-Version: 13.1.0
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X-Bugzilla-Who: csaba_22 at yahoo dot co.uk
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D110330

            Bug ID: 110330
           Summary: GCC does not diagnose ambiguous function introduced
                    from base class
           Product: gcc
           Version: 13.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: csaba_22 at yahoo dot co.uk
  Target Milestone: ---

The following code

struct Foo{};
struct Bar{};

struct Base {
    Foo func1(const Foo , const Bar =3D Bar{}) const {
        return {};
    };
};

struct Derived : public Base {
    using Base::func1;
    Foo func1(const Foo ) const {
        return {};
    };
};

int main() {
    Foo foo;
    Derived der;
    der.func1(foo);
}

is rejected by ICX and clang, but accepted by GCC (up to 13.1).
https://godbolt.org/z/4M3rrs3r4

The consensus at
https://stackoverflow.com/questions/76517300/gcc-does-not-see-function-intr=
oduced-from-base-class-as-ambiguous
seems to be that this is a bug.

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D84832 was shown as a possible
duplicate, although the problem there wasn't ambiguity.=