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Rollup merge of #110555 - compiler-errors:subst-missing-trait-items, r=cjgillot

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Substitute missing trait items suggestion correctly

Properly substitute missing item suggestions, so that when they reference generics from their parent trait they actually have the right time for the impl.

Also, some other minor tweaks like using `/* Type */` to signify a GAT's type is actually missing, and fixing generic arg suggestions for GATs in general.
This commit is contained in:
Matthias Krüger 2023-04-21 06:44:29 +02:00 • committed by GitHub
commit 7d046551a7
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GPG key ID: 4AEE18F83AFDEB23
16 changed files with 100 additions and 62 deletions
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2
compiler/rustc_hir_analysis/src/check/check.rs
View file

@ -863,7 +863,7 @@ fn check_impl_items_against_trait<'tcx>(
if !missing_items.is_empty() {
let full_impl_span =
tcx.hir().span_with_body(tcx.hir().local_def_id_to_hir_id(impl_id));
missing_items_err(tcx, tcx.def_span(impl_id), &missing_items, full_impl_span);
missing_items_err(tcx, impl_id, &missing_items, full_impl_span);
}
if let Some(missing_items) = must_implement_one_of {

41
compiler/rustc_hir_analysis/src/check/mod.rs
View file

@ -198,7 +198,7 @@ fn report_forbidden_specialization(tcx: TyCtxt<'_>, impl_item: DefId, parent_imp
fn missing_items_err(
tcx: TyCtxt<'_>,
impl_span: Span,
impl_def_id: LocalDefId,
missing_items: &[ty::AssocItem],
full_impl_span: Span,
) {
@ -211,6 +211,7 @@ fn missing_items_err(
.collect::<Vec<_>>()
.join("`, `");
let impl_span = tcx.def_span(impl_def_id);
let mut err = struct_span_err!(
tcx.sess,
impl_span,
@ -229,7 +230,11 @@ fn missing_items_err(
tcx.sess.source_map().indentation_before(sugg_sp).unwrap_or_else(|| String::new());
for &trait_item in missing_items {
let snippet = suggestion_signature(trait_item, tcx);
let snippet = suggestion_signature(
tcx,
trait_item,
tcx.impl_trait_ref(impl_def_id).unwrap().subst_identity(),
);
let code = format!("{}{}\n{}", padding, snippet, padding);
let msg = format!("implement the missing item: `{snippet}`");
let appl = Applicability::HasPlaceholders;
@ -301,11 +306,11 @@ fn default_body_is_unstable(
/// Re-sugar `ty::GenericPredicates` in a way suitable to be used in structured suggestions.
fn bounds_from_generic_predicates<'tcx>(
tcx: TyCtxt<'tcx>,
predicates: ty::GenericPredicates<'tcx>,
predicates: impl IntoIterator<Item = (ty::Predicate<'tcx>, Span)>,
) -> (String, String) {
let mut types: FxHashMap<Ty<'tcx>, Vec<DefId>> = FxHashMap::default();
let mut projections = vec![];
for (predicate, _) in predicates.predicates {
for (predicate, _) in predicates {
debug!("predicate {:?}", predicate);
let bound_predicate = predicate.kind();
match bound_predicate.skip_binder() {
@ -367,7 +372,7 @@ fn fn_sig_suggestion<'tcx>(
tcx: TyCtxt<'tcx>,
sig: ty::FnSig<'tcx>,
ident: Ident,
predicates: ty::GenericPredicates<'tcx>,
predicates: impl IntoIterator<Item = (ty::Predicate<'tcx>, Span)>,
assoc: ty::AssocItem,
) -> String {
let args = sig
@ -436,7 +441,17 @@ pub fn ty_kind_suggestion(ty: Ty<'_>) -> Option<&'static str> {
/// Return placeholder code for the given associated item.
/// Similar to `ty::AssocItem::suggestion`, but appropriate for use as the code snippet of a
/// structured suggestion.
fn suggestion_signature(assoc: ty::AssocItem, tcx: TyCtxt<'_>) -> String {
fn suggestion_signature<'tcx>(
tcx: TyCtxt<'tcx>,
assoc: ty::AssocItem,
impl_trait_ref: ty::TraitRef<'tcx>,
) -> String {
let substs = ty::InternalSubsts::identity_for_item(tcx, assoc.def_id).rebase_onto(
tcx,
assoc.container_id(tcx),
impl_trait_ref.with_self_ty(tcx, tcx.types.self_param).substs,
);
match assoc.kind {
ty::AssocKind::Fn => {
// We skip the binder here because the binder would deanonymize all
@ -445,16 +460,22 @@ fn suggestion_signature(assoc: ty::AssocItem, tcx: TyCtxt<'_>) -> String {
// regions just fine, showing `fn(&MyType)`.
fn_sig_suggestion(
tcx,
tcx.fn_sig(assoc.def_id).subst_identity().skip_binder(),
tcx.fn_sig(assoc.def_id).subst(tcx, substs).skip_binder(),
assoc.ident(tcx),
tcx.predicates_of(assoc.def_id),
tcx.predicates_of(assoc.def_id).instantiate_own(tcx, substs),
assoc,
)
}
ty::AssocKind::Type => format!("type {} = Type;", assoc.name),
ty::AssocKind::Type => {
let (generics, where_clauses) = bounds_from_generic_predicates(
tcx,
tcx.predicates_of(assoc.def_id).instantiate_own(tcx, substs),
);
format!("type {}{generics} = /* Type */{where_clauses};", assoc.name)
}
ty::AssocKind::Const => {
let ty = tcx.type_of(assoc.def_id).subst_identity();
let val = ty_kind_suggestion(ty).unwrap_or("value");
let val = ty_kind_suggestion(ty).unwrap_or("todo!()");
format!("const {}: {} = {};", assoc.name, ty, val)
}
}