bjoernager/rust
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Auto merge of #113201 - oli-obk:recursive_type_alias, r=estebank,compiler-errors

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Permit recursive weak type aliases

I saw #63097 and thought "we can do ~~better~~ funnier". So here it is. It's not useful, but it's certainly something. This may actually become feasible with lazy norm (so in 5 years (constant, not reducing over time)).

r? `@estebank`

cc `@GuillaumeGomez`
This commit is contained in:
bors 2023-09-01 07:10:21 +00:00
commit 96f62fce00
9 changed files with 104 additions and 22 deletions
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21
compiler/rustc_trait_selection/src/traits/project.rs
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@ -659,6 +659,18 @@ impl<'a, 'b, 'tcx> TypeFolder<TyCtxt<'tcx>> for AssocTypeNormalizer<'a, 'b, 'tcx
normalized_ty
}
ty::Weak => {
let recursion_limit = self.interner().recursion_limit();
if !recursion_limit.value_within_limit(self.depth) {
self.selcx.infcx.err_ctxt().report_overflow_error(
&ty,
self.cause.span,
false,
|diag| {
diag.note(crate::fluent_generated::trait_selection_ty_alias_overflow);
},
);
}
let infcx = self.selcx.infcx;
self.obligations.extend(
infcx.tcx.predicates_of(data.def_id).instantiate_own(infcx.tcx, data.args).map(
@ -678,7 +690,14 @@ impl<'a, 'b, 'tcx> TypeFolder<TyCtxt<'tcx>> for AssocTypeNormalizer<'a, 'b, 'tcx
},
),
);
infcx.tcx.type_of(data.def_id).instantiate(infcx.tcx, data.args).fold_with(self)
self.depth += 1;
let res = infcx
.tcx
.type_of(data.def_id)
.instantiate(infcx.tcx, data.args)
.fold_with(self);
self.depth -= 1;
res
}
ty::Inherent if !data.has_escaping_bound_vars() => {