Separate functions from comptime functions in the type system

[jfecher]

Problem

It is possible for comptime functions to not be found and evaluated at compile-time, e.g:

let bad = my_comptime_only_function;
bad(); // Call is not registered as comptime

Happy Case

comptime functions are assigned a different type from regular functions: comptime fn(). This can then be checked for when calling functions to determine whether to do so at compile-time or not, and can also be used to issue an error if it cannot be evaluated at compile-time do to being mixed in runtime code, e.g:

fn main(x: bool) {
    if x {
        my_comptime_fn1
    } else {
        my_comptime_fn2
    }();
}

Project Impact

None

Impact Context

No response

Workaround

None

Workaround Description

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Additional Context

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