[clangd] [Signature help] [C++23] Parameter hints do not appear for static operator (and some obscure interaction with templates)

[timon-ul]

In the following example code I do not get any parameter hints for the operator, but if I manually type in true clangd recognizes that I am calling the operator.

Details

struct Abc {
    static void operator()(bool a) {}
};

void test() {
    Abc abc;
    abc(^);
}

If I remove the static from the operator definition I do get the paramtere hints.

Details

struct Abc {
    void operator()(bool a) {}
};

void test() {
    Abc abc;
    abc(^);
}

As straight forward as this bug seems to be, I stumbled upon some more odd behaviour. Consider now me using 2 parameters, this still does not work with static as you can see here.

Details

struct Abc {
    static void operator()(bool a, bool b) {}
};

void test() {
    Abc abc;
    abc(^);
}

But if I now template my operator it does work.

Details

struct Abc {
    template <typename T>
    static void operator()(T a, bool b) {}
};

void test() {
    Abc abc;
    abc(^);
}

The odd part here is that I need 2 parameters for my operator, because the templated version with only 1 parameter does not work.

Details

struct Abc {
    template <typename T>
    static void operator()(T a) {}
};

void test() {
    Abc abc;
    abc(^);
}

Also it is important that the template type is used in the parameters, otherwise it does not work.

Details

struct Abc {
    template <typename T>
    static void operator()(bool a, bool b) { T c; }
};

void test() {
    Abc abc;
    abc(^);
}

[llvmorg-github-actions]

@llvm/issue-subscribers-clangd

Author: timon-ul

Details

In the following example code I do not get any parameter hints for the operator, but if I manually type in `true` clangd recognizes that I am calling the operator.

<img width="540" height="300" alt="Image" src="https://github.com/user-attachments/assets/6022fb65-6219-4d0b-949a-a8064f798d0f" />

If I remove the static from the operator definition I do get the paramtere hints.

<img width="527" height="315" alt="Image" src="https://github.com/user-attachments/assets/a437c6f4-3e60-4fbb-8b6f-70c7e687e39f" />

As straight forward as this bug seems to be, I stumbled upon some more odd behaviour. Consider now me using 2 parameters, this still does not work with static as you can see here.

<img width="652" height="301" alt="Image" src="https://github.com/user-attachments/assets/2df5c84a-2052-4885-a0bb-51a600b89631" />

But if I now template my operator it does work.

<img width="635" height="336" alt="Image" src="https://github.com/user-attachments/assets/b9bb201c-4c08-472e-91ee-db8aa49b590d" />

The odd part here is that I need 2 parameters for my operator, because the templated version with only 1 parameter does not work.

<img width="532" height="323" alt="Image" src="https://github.com/user-attachments/assets/ef628ad0-cab3-43a9-a4f5-8b33f07ff509" />

Also it is important that the template type is used in the parameters, otherwise it does not work.

<img width="736" height="346" alt="Image" src="https://github.com/user-attachments/assets/3f0c45ff-de85-4a3d-bdcd-d27ec5c258c3" />

[Ippo47]

Hi I would like to work on this issue

[timon-ul]

Hi @Ippo47, feel free to work on this issue, I will gladly be your reviewer! I have not yet had the time to do any kind of investigation so far, so I cannot provide you any hints as to where this is going wrong, but otherwise I will happily help you out where I can :) .