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Replace if/elseif chain with match

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This commit is contained in:
Oli Scherer
2025-04-28 08:55:11 +00:00
parent 1b8ab72680
commit 19fc3a1a6e
1 changed files with 79 additions and 60 deletions
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139
compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
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@@ -66,71 +66,90 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
let def_id = obligation.predicate.def_id();
let tcx = self.tcx();
if tcx.is_lang_item(def_id, LangItem::Copy) {
debug!(obligation_self_ty = ?obligation.predicate.skip_binder().self_ty());
let lang_item = tcx.as_lang_item(def_id);
match lang_item {
Some(LangItem::Copy | LangItem::Clone) => {
debug!(obligation_self_ty = ?obligation.predicate.skip_binder().self_ty());
// User-defined copy impls are permitted, but only for
// structs and enums.
self.assemble_candidates_from_impls(obligation, &mut candidates);
// User-defined copy impls are permitted, but only for
// structs and enums.
self.assemble_candidates_from_impls(obligation, &mut candidates);
// For other types, we'll use the builtin rules.
let copy_conditions = self.copy_clone_conditions(obligation);
self.assemble_builtin_bound_candidates(copy_conditions, &mut candidates);
} else if tcx.is_lang_item(def_id, LangItem::DiscriminantKind) {
// `DiscriminantKind` is automatically implemented for every type.
candidates.vec.push(BuiltinCandidate { has_nested: false });
} else if tcx.is_lang_item(def_id, LangItem::PointeeTrait) {
// `Pointee` is automatically implemented for every type.
candidates.vec.push(BuiltinCandidate { has_nested: false });
} else if tcx.is_lang_item(def_id, LangItem::Sized) {
self.assemble_builtin_sized_candidate(obligation, &mut candidates);
} else if tcx.is_lang_item(def_id, LangItem::Unsize) {
self.assemble_candidates_for_unsizing(obligation, &mut candidates);
} else if tcx.is_lang_item(def_id, LangItem::Destruct) {
self.assemble_const_destruct_candidates(obligation, &mut candidates);
} else if tcx.is_lang_item(def_id, LangItem::TransmuteTrait) {
// User-defined transmutability impls are permitted.
self.assemble_candidates_from_impls(obligation, &mut candidates);
self.assemble_candidates_for_transmutability(obligation, &mut candidates);
} else if tcx.is_lang_item(def_id, LangItem::Tuple) {
self.assemble_candidate_for_tuple(obligation, &mut candidates);
} else if tcx.is_lang_item(def_id, LangItem::FnPtrTrait) {
self.assemble_candidates_for_fn_ptr_trait(obligation, &mut candidates);
} else if tcx.is_lang_item(def_id, LangItem::BikeshedGuaranteedNoDrop) {
self.assemble_candidates_for_bikeshed_guaranteed_no_drop_trait(
obligation,
&mut candidates,
);
} else {
if tcx.is_lang_item(def_id, LangItem::Clone) {
// Same builtin conditions as `Copy`, i.e., every type which has builtin support
// for `Copy` also has builtin support for `Clone`, and tuples/arrays of `Clone`
// types have builtin support for `Clone`.
let clone_conditions = self.copy_clone_conditions(obligation);
self.assemble_builtin_bound_candidates(clone_conditions, &mut candidates);
// For other types, we'll use the builtin rules.
let copy_conditions = self.copy_clone_conditions(obligation);
self.assemble_builtin_bound_candidates(copy_conditions, &mut candidates);
}
if tcx.is_lang_item(def_id, LangItem::Coroutine) {
self.assemble_coroutine_candidates(obligation, &mut candidates);
} else if tcx.is_lang_item(def_id, LangItem::Future) {
self.assemble_future_candidates(obligation, &mut candidates);
} else if tcx.is_lang_item(def_id, LangItem::Iterator) {
self.assemble_iterator_candidates(obligation, &mut candidates);
} else if tcx.is_lang_item(def_id, LangItem::FusedIterator) {
self.assemble_fused_iterator_candidates(obligation, &mut candidates);
} else if tcx.is_lang_item(def_id, LangItem::AsyncIterator) {
self.assemble_async_iterator_candidates(obligation, &mut candidates);
} else if tcx.is_lang_item(def_id, LangItem::AsyncFnKindHelper) {
self.assemble_async_fn_kind_helper_candidates(obligation, &mut candidates);
Some(LangItem::DiscriminantKind) => {
// `DiscriminantKind` is automatically implemented for every type.
candidates.vec.push(BuiltinCandidate { has_nested: false });
}
Some(LangItem::PointeeTrait) => {
// `Pointee` is automatically implemented for every type.
candidates.vec.push(BuiltinCandidate { has_nested: false });
}
Some(LangItem::Sized) => {
self.assemble_builtin_sized_candidate(obligation, &mut candidates);
}
Some(LangItem::Unsize) => {
self.assemble_candidates_for_unsizing(obligation, &mut candidates);
}
Some(LangItem::Destruct) => {
self.assemble_const_destruct_candidates(obligation, &mut candidates);
}
Some(LangItem::TransmuteTrait) => {
// User-defined transmutability impls are permitted.
self.assemble_candidates_from_impls(obligation, &mut candidates);
self.assemble_candidates_for_transmutability(obligation, &mut candidates);
}
Some(LangItem::Tuple) => {
self.assemble_candidate_for_tuple(obligation, &mut candidates);
}
Some(LangItem::FnPtrTrait) => {
self.assemble_candidates_for_fn_ptr_trait(obligation, &mut candidates);
}
Some(LangItem::BikeshedGuaranteedNoDrop) => {
self.assemble_candidates_for_bikeshed_guaranteed_no_drop_trait(
obligation,
&mut candidates,
);
}
_ => {
// We re-match here for traits that can have both builtin impls and user written impls.
// After the builtin impls we need to also add user written impls, which we do not want to
// do in general because just checking if there are any is expensive.
match lang_item {
Some(LangItem::Coroutine) => {
self.assemble_coroutine_candidates(obligation, &mut candidates);
}
Some(LangItem::Future) => {
self.assemble_future_candidates(obligation, &mut candidates);
}
Some(LangItem::Iterator) => {
self.assemble_iterator_candidates(obligation, &mut candidates);
}
Some(LangItem::FusedIterator) => {
self.assemble_fused_iterator_candidates(obligation, &mut candidates);
}
Some(LangItem::AsyncIterator) => {
self.assemble_async_iterator_candidates(obligation, &mut candidates);
}
Some(LangItem::AsyncFnKindHelper) => {
self.assemble_async_fn_kind_helper_candidates(
obligation,
&mut candidates,
);
}
_ => {
// FIXME: Put these into match arms above, since they're built-in.
self.assemble_closure_candidates(obligation, &mut candidates);
self.assemble_async_closure_candidates(obligation, &mut candidates);
self.assemble_fn_pointer_candidates(obligation, &mut candidates);
}
}
// FIXME: Put these into `else if` blocks above, since they're built-in.
self.assemble_closure_candidates(obligation, &mut candidates);
self.assemble_async_closure_candidates(obligation, &mut candidates);
self.assemble_fn_pointer_candidates(obligation, &mut candidates);
self.assemble_candidates_from_impls(obligation, &mut candidates);
self.assemble_candidates_from_object_ty(obligation, &mut candidates);
self.assemble_candidates_from_impls(obligation, &mut candidates);
self.assemble_candidates_from_object_ty(obligation, &mut candidates);
}
}
self.assemble_candidates_from_projected_tys(obligation, &mut candidates);