Immediate functions returning void in Clang

Question

Clang++ produces linker error if one calls immediate function returning void not from a context of another immediate function as in the example:

consteval void f(int * x) { 
    if(x) *x = 1; 
}

consteval int g() {
    int y = 0;
    f(&y);
    return y;
}

int main() {
    (void)g(); //ok everywhere
    f(nullptr); //linker error in Clang
}

The error is:

undefined reference to `f(int*)'

Demo: https://gcc.godbolt.org/z/PT8ezfnrW

The error disappears if the immediate function returns anything but void, for example:

consteval int f(int * x) { 
    if(x) *x = 1; 
    return 1;
}

Demo: https://gcc.godbolt.org/z/hfzrM688E

Is it just a bug in Clang?

Roble

#63365418 – Rumble

@KamilCuk, thanks for the reference. It is said there that the bug is fixed, but it does not look so. At least it is manifested differently now. – Roble

LLVM bugzilla and stackoverflow are 2 distinctly different websites. And this here is an obvious bug. :-) – Smalto

Add these to the top of the file: #ifndef __cpp_consteval and #error consteval not supported and #endif – Merv

Hmm, this must be a bug. There shouldn't be anything to link if it's consteval. – Unshakable

I reported this bug to llvm: bugs.llvm.org/show_bug.cgi?id=52183 – Roble