rust/tests/run-pass/track-caller-attribute.rs

#![feature(core_intrinsics)]

use std::panic::Location;

#[track_caller]
fn tracked() -> &'static Location<'static> {
    Location::caller() // most importantly, we never get line 7
}

fn nested_intrinsic() -> &'static Location<'static> {
    Location::caller()
}

fn nested_tracked() -> &'static Location<'static> {
    tracked()
}

macro_rules! caller_location_from_macro {
    () => (core::panic::Location::caller());
}

fn test_fn_ptr() {
    fn pass_to_ptr_call<T>(f: fn(T), x: T) {
        f(x);
    }

    #[track_caller]
    fn tracked_unit(_: ()) {
        let expected_line = line!() - 1;
        let location = std::panic::Location::caller();
        assert_eq!(location.file(), file!());
        assert_eq!(location.line(), expected_line, "call shims report location as fn definition");
    }

    pass_to_ptr_call(tracked_unit, ());
}

fn test_trait_obj() {
    trait Tracked {
        #[track_caller]
        fn handle(&self) { // `fn` here is what the `location` should point at.
            let location = std::panic::Location::caller();
            assert_eq!(location.file(), file!());
            // we only call this via trait object, so the def site should *always* be returned
            assert_eq!(location.line(), line!() - 4);
            assert_eq!(location.column(), 9);
        }
    }

    impl Tracked for () {}
    impl Tracked for u8 {}

    let tracked: &dyn Tracked = &5u8;
    tracked.handle();

    const TRACKED: &dyn Tracked = &();
    TRACKED.handle();
}

fn main() {
    let location = Location::caller();
    let expected_line = line!() - 1;
    assert_eq!(location.file(), file!());
    assert_eq!(location.line(), expected_line);
    assert_eq!(location.column(), 20);

    let tracked = tracked();
    let expected_line = line!() - 1;
    assert_eq!(tracked.file(), file!());
    assert_eq!(tracked.line(), expected_line);
    assert_eq!(tracked.column(), 19);

    let nested = nested_intrinsic();
    assert_eq!(nested.file(), file!());
    assert_eq!(nested.line(), 11);
    assert_eq!(nested.column(), 5);

    let contained = nested_tracked();
    assert_eq!(contained.file(), file!());
    assert_eq!(contained.line(), 15);
    assert_eq!(contained.column(), 5);

    // `Location::caller()` in a macro should behave similarly to `file!` and `line!`,
    // i.e. point to where the macro was invoked, instead of the macro itself.
    let inmacro = caller_location_from_macro!();
    let expected_line = line!() - 1;
    assert_eq!(inmacro.file(), file!());
    assert_eq!(inmacro.line(), expected_line);
    assert_eq!(inmacro.column(), 19);

    let intrinsic = core::intrinsics::caller_location();
    let expected_line = line!() - 1;
    assert_eq!(intrinsic.file(), file!());
    assert_eq!(intrinsic.line(), expected_line);
    assert_eq!(intrinsic.column(), 21);

    test_fn_ptr();
    test_trait_obj();
}