BROKEN: Attempt to support #[track_caller] #354
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Bizarre interaction between const-eval, macro span, #[track_caller], and Location::caller. Tried many different combinations of inline const, const-fn and const declaration.
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Attempt to fix issue #342
Due to the need to create
&'static RecordStaticat compile time, this is much more difficult than adding support in the log crate.I tried various combination of inline const and const declaration.
In each case, the
track_caller::track_callertest failed to respect the#[track_caller]attribute.It turns out that there is a bizarre interaction that meansLocation::callerdoes not respect#[track_caller]in a const-eval context.EDIT: This is not a "bizzare interaction", it is a fundamental limitation of const-eval.
See here for a demo: https://gist.github.com/Techcable/a80e3a4c4d928a2038dc45bd6d91f9e4
You can also run this in the playground.
A workaround would be adding a
&'static Locationto theslog::Recordstruct, but this would add another pointer to the record and possibly break backwards compatibility.