// run-pass trait Tracked { #[track_caller] fn track_caller_trait_method(&self, line: u32, col: u32) { let location = std::panic::Location::caller(); assert_eq!(location.file(), file!()); // The trait method definition is annotated with `#[track_caller]`, // so caller location information will work through a method // call on a trait object assert_eq!(location.line(), line, "Bad line"); assert_eq!(location.column(), col, "Bad col"); } fn track_caller_not_on_trait_method(&self); #[track_caller] fn track_caller_through_self(self: Box, line: u32, col: u32); } impl Tracked for () { // We have `#[track_caller]` on the implementation of the method, // but not on the definition of the method in the trait. Therefore, // caller location information will *not* work through a method call // on a trait object. Instead, we will get the location of this method #[track_caller] fn track_caller_not_on_trait_method(&self) { let location = std::panic::Location::caller(); assert_eq!(location.file(), file!()); assert_eq!(location.line(), line!() - 3); assert_eq!(location.column(), 5); } // We don't have a `#[track_caller]` attribute, but // `#[track_caller]` is present on the trait definition, // so we'll still get location information fn track_caller_through_self(self: Box, line: u32, col: u32) { let location = std::panic::Location::caller(); assert_eq!(location.file(), file!()); // The trait method definition is annotated with `#[track_caller]`, // so caller location information will work through a method // call on a trait object assert_eq!(location.line(), line, "Bad line"); assert_eq!(location.column(), col, "Bad col"); } } fn main() { let tracked: &dyn Tracked = &(); // The column is the start of 'track_caller_trait_method' tracked.track_caller_trait_method(line!(), 13); const TRACKED: &dyn Tracked = &(); // The column is the start of 'track_caller_trait_method' TRACKED.track_caller_trait_method(line!(), 13); TRACKED.track_caller_not_on_trait_method(); // The column is the start of `track_caller_through_self` let boxed: Box = Box::new(()); boxed.track_caller_through_self(line!(), 11); }