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

struct TailCallCkVisitor<'a, 'tcx> {
    ... // existed fields
    def: DefId,
}

And create it like this

    let mut 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]

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.