Fix an ICE on #96738

[JohnTitor]

In the block we don't know if the method actually exists thus expect_local panics.
Fixes #96738
Fixes #96583

[rust-highfive]

r? @petrochenkov

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[SNCPlay42]

I don't think this code should need a local ID, it should be rewritten to be able to handle non-local definitions.

[JohnTitor]

Though it's more of an enhancement thing rather than bugfix, I guess.

[petrochenkov]

I also think it would be better to support this for extern ids.
Once we know that the def_id is DefKind::Ctor we can take a tcx.parent(def_id) from it and then use tcx.associated_item_def_ids(parent_def_id).len() to obtain the number of fields.

[JohnTitor]

Hmm, I may be misunderstanding your suggestion.
This:

let suggest = if let ty::FnDef(def_id, _) = rcvr_ty.kind()
                            && let DefKind::Ctor(of, _) = tcx.def_kind(def_id)
                        {
                            let parent_def_id = tcx.parent(*def_id);
                            Some((tcx.associated_item_def_ids(parent_def_id).len(), of))
                        } else {
                            None
                        };

causes panic on tcx.hir().expect_item(def_id.expect_local()) of associated_item_def_ids (we would assume def_id is local anyway?). Any idea?

[petrochenkov]

Sigh, looks like the local version of associated_item_def_ids doesn't work with fields as is.
Could you then use associated_item_def_ids for extern def-ids only, and use the old logic for local def-ids?

[JohnTitor]

Added the implementation.

[Badel2]

This also fixes #96583, which is the same issue

[petrochenkov]

@bors r+

[bors]

📌 Commit 35d77c1 has been approved by petrochenkov