Tail call diagnostics to include lifetime info

[Kivooeo]

Fixes#144957

r? @WaffleLapkin@compiler-errors

[rustbot]

WaffleLapkin is not on the review rotation at the moment.
They may take a while to respond.

[compiler-errors]

This doesn't fix the issue in the other direction, like:

fn foo(_: fn(&())) {
become bar(dummy);
}
fn bar<'a>(_: fn(&'a ())) {}
fn dummy(_: &()) {}

[compiler-errors]

Suggested change

	self.caller_ty.fn_sig(self.tcx).skip_binder(),
	self.caller_ty.fn_sig(self.tcx).instantiate_identity(),

[Kivooeo]

It does not work for me

error[E0599]: no method named `instantiate_identity` found for struct `Binder` in the current scope
--> compiler/rustc_mir_build/src/check_tail_calls.rs:137:53
|
137 | self.caller_ty.fn_sig(self.tcx).instantiate_identity(),
| ^^^^^^^^^^^^^^^^^^^^ method not found in `Binder<TyCtxt<'_>,FnSig<TyCtxt<'_>>>`

[compiler-errors]

oh, it's a binder, not an early binder. that should be liberated then probably, use tcx.liberate_late_bound_regions instead.

[Kivooeo]

I'd love to hear why current approach is not best just to learn things

Also about 'static yes it shows, should I include this in test?

4 | become bar(dummy);
| ^^^^^^^^^^^^^^^^^
|
= note: -Ztrack-diagnostics: created at compiler/rustc_mir_build/src/check_tail_calls.rs:368:14
= note: `become` requires caller and callee to have matching signatures
= note: caller signature: `fn(for<'a> fn(&'a ()))`
= note: callee signature: `fn(fn(&'static ()))`

[Kivooeo]

I did tcx.liberate_late_bound_regions it works but I did not found a better way to obtain DefId rather than do this

Update TailCallCkVisitor with adding a field that will contain def id

structTailCallCkVisitor<'a,'tcx>{
... // existed fieldsdef:DefId,}

And create it like this

letmut visitor = TailCallCkVisitor{
...// eixsted fields
def: def.to_def_id(),};

This might be a bad solution to pass DefId like this?

self.report_arguments_mismatch(
expr.span,self.tcx.liberate_late_bound_regions(self.def,self.caller_ty.fn_sig(self.tcx)),self.tcx.liberate_late_bound_regions(self.def, ty.fn_sig(self.tcx)),);

[Kivooeo]

Hey @compiler-errors, when you have a moment, could you take another look and let me know which approach you think works better?

[compiler-errors]

It doesn't actually matter what def id you pass. Can you just pass CRATE_DEF_ID for now?

[Kivooeo]

yeah, CRATE_DEF_ID works, didn't knew about this one

[Kivooeo]

I fixed other direction, and make test description lesser (not want to shrink it to one liner tho)

If we have a better way to do so, I'm open for suggestions because it's literally first time me opening anything related to tail call

[compiler-errors]

You should probably check if this also mentions regions like 'static since those may show up in the signature.

[WaffleLapkin]

r? compiler-errors

[rustbot]

compiler-errors is not on the review rotation at the moment.
They may take a while to respond.

[compiler-errors]

@rustbot author

[Kivooeo]

Added 'static test and used liberate_late_bound_regions, it looks more verbose but works too, so should be fine @rustbot ready

[compiler-errors]

@bors r+ rollup

[bors]

📌 Commit 51df1da has been approved by compiler-errors

It is now in the queue for this repository.