[clang] Question about devirtualization

[vient]

Here is the test case

struct A {
    virtual int f() {
        return 1;
    }

    int call_f() {
        return f();
    }
};

struct C final: public A {
    int f() override {
        return 3;
    }
};

int test1(C& c) {
    return c.f();
}

int test2(C& c) {
    return c.call_f();
}

Both Clang and GCC devirtualize f call in test1 but not in test2 - why is that so? C is final, what is the scenario when call to C::call_f does not lead to C::f?
https://godbolt.org/z/6Kv38jeYo

[efriedma-quic]

At least in clang, it's a layering issue; the clang frontend is aware that we have a "C" object, so if it sees a call, it can devirtualize. But that fact isn't recorded into LLVM IR, so we can't devirtualize after inlining.

I think this is a duplicate of #61950.