fix(resolve): skip assertion judgment when NonModule is dummy

[bvanjoi]

Fixes #85992

Why #85992 panic

During resolve_imports, the path_res of the import issue_85992_extern_2::Outcome is pointing to external::issue_85992_extern_2 instead of crate::issue_85992_extern_2. As a result import.imported_module.set had been executed.

Attached 1: the state of early_resolve_ident_in_lexical_scope during the resolve_imports for use issue_85992_extern_2::Outcome is as follows:

iter in visit_scopes	scope	result.binding
init	-	-
0	CrateRoot	Err(Determined)
1	ExternPrelude	pointing to the issue_85992_extern_2(external)

However, during finalization for issue_85992_extern_2::Outcome, the innermost_result was pointed to crate::issue_85992_extern_2 and no ambiguity was generated, leading to a panic.

Attached 2: the state of early_resolve_ident_in_lexical_scope during the finalize_import for use issue_85992_extern_2::Outcome is as follows:

iter in visit_scopes	scope	result.binding	innermost_result
init	-	-	None
0	CrateRoot	pointing to use crate::issue_85992_extern_2 (introdcued by dummy)	same as result but with a Some wapper
1	ExternPrelude	pointing to the issue_85992_extern_2(external)	smae as above

Try to solve

Skip assertion judgment when NonModule is dummy

r? @petrochenkov

[petrochenkov]

That assert is too strict, IMO.

If a dummy binding can get in the way during finalize_import, then it can be relaxed to

            PathResult::NonModule(partial_res) => {
                if no_ambiguity && partial_res.full_res() != Some(Res::Err) {
                    assert!(import.imported_module.get().is_none());
                }

Changing the early_resolve_ident_in_lexical_scope infra can have more far reaching consequences, and I don't really want to think about them if the issue can be fixed in a more local way.
@rustbot author

[bvanjoi]

@rustbot ready

[petrochenkov]

Thanks!
@bors r+ rollup

[bors]

📌 Commit 549f48d has been approved by petrochenkov

It is now in the queue for this repository.