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Use suggest_impl_trait in return type suggestion

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This commit is contained in:
Michael Goulet 2024-04-10 18:42:48 -04:00
parent b3bd7058c1
commit 3764af6119
7 changed files with 68 additions and 60 deletions
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98
compiler/rustc_hir_analysis/src/collect.rs
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@ -30,7 +30,7 @@ use rustc_middle::query::Providers;
use rustc_middle::ty::util::{Discr, IntTypeExt};
use rustc_middle::ty::{self, AdtKind, Const, IsSuggestable, ToPredicate, Ty, TyCtxt};
use rustc_span::symbol::{kw, sym, Ident, Symbol};
use rustc_span::Span;
use rustc_span::{Span, DUMMY_SP};
use rustc_target::abi::FieldIdx;
use rustc_target::spec::abi;
use rustc_trait_selection::infer::InferCtxtExt;
@ -1383,7 +1383,9 @@ fn infer_return_ty_for_fn_sig<'tcx>(
Applicability::MachineApplicable,
);
should_recover = true;
} else if let Some(sugg) = suggest_impl_trait(tcx, ret_ty, ty.span, def_id) {
} else if let Some(sugg) =
suggest_impl_trait(&tcx.infer_ctxt().build(), tcx.param_env(def_id), ret_ty)
{
diag.span_suggestion(
ty.span,
"replace with an appropriate return type",
@ -1426,11 +1428,10 @@ fn infer_return_ty_for_fn_sig<'tcx>(
}
}
fn suggest_impl_trait<'tcx>(
tcx: TyCtxt<'tcx>,
pub fn suggest_impl_trait<'tcx>(
infcx: &InferCtxt<'tcx>,
param_env: ty::ParamEnv<'tcx>,
ret_ty: Ty<'tcx>,
span: Span,
def_id: LocalDefId,
) -> Option<String> {
let format_as_assoc: fn(_, _, _, _, _) -> _ =
|tcx: TyCtxt<'tcx>,
@ -1464,24 +1465,28 @@ fn suggest_impl_trait<'tcx>(
for (trait_def_id, assoc_item_def_id, formatter) in [
(
tcx.get_diagnostic_item(sym::Iterator),
tcx.get_diagnostic_item(sym::IteratorItem),
infcx.tcx.get_diagnostic_item(sym::Iterator),
infcx.tcx.get_diagnostic_item(sym::IteratorItem),
format_as_assoc,
),
(
tcx.lang_items().future_trait(),
tcx.get_diagnostic_item(sym::FutureOutput),
infcx.tcx.lang_items().future_trait(),
infcx.tcx.get_diagnostic_item(sym::FutureOutput),
format_as_assoc,
),
(tcx.lang_items().fn_trait(), tcx.lang_items().fn_once_output(), format_as_parenthesized),
(
tcx.lang_items().fn_mut_trait(),
tcx.lang_items().fn_once_output(),
infcx.tcx.lang_items().fn_trait(),
infcx.tcx.lang_items().fn_once_output(),
format_as_parenthesized,
),
(
tcx.lang_items().fn_once_trait(),
tcx.lang_items().fn_once_output(),
infcx.tcx.lang_items().fn_mut_trait(),
infcx.tcx.lang_items().fn_once_output(),
format_as_parenthesized,
),
(
infcx.tcx.lang_items().fn_once_trait(),
infcx.tcx.lang_items().fn_once_output(),
format_as_parenthesized,
),
] {
@ -1491,36 +1496,45 @@ fn suggest_impl_trait<'tcx>(
let Some(assoc_item_def_id) = assoc_item_def_id else {
continue;
};
if tcx.def_kind(assoc_item_def_id) != DefKind::AssocTy {
if infcx.tcx.def_kind(assoc_item_def_id) != DefKind::AssocTy {
continue;
}
let param_env = tcx.param_env(def_id);
let infcx = tcx.infer_ctxt().build();
let args = ty::GenericArgs::for_item(tcx, trait_def_id, |param, _| {
if param.index == 0 { ret_ty.into() } else { infcx.var_for_def(span, param) }
let sugg = infcx.probe(|_| {
let args = ty::GenericArgs::for_item(infcx.tcx, trait_def_id, |param, _| {
if param.index == 0 { ret_ty.into() } else { infcx.var_for_def(DUMMY_SP, param) }
});
if !infcx
.type_implements_trait(trait_def_id, args, param_env)
.must_apply_modulo_regions()
{
return None;
}
let ocx = ObligationCtxt::new(&infcx);
let item_ty = ocx.normalize(
&ObligationCause::dummy(),
param_env,
Ty::new_projection(infcx.tcx, assoc_item_def_id, args),
);
// FIXME(compiler-errors): We may benefit from resolving regions here.
if ocx.select_where_possible().is_empty()
&& let item_ty = infcx.resolve_vars_if_possible(item_ty)
&& let Some(item_ty) = item_ty.make_suggestable(infcx.tcx, false, None)
&& let Some(sugg) = formatter(
infcx.tcx,
infcx.resolve_vars_if_possible(args),
trait_def_id,
assoc_item_def_id,
item_ty,
)
{
return Some(sugg);
}
None
});
if !infcx.type_implements_trait(trait_def_id, args, param_env).must_apply_modulo_regions() {
continue;
}
let ocx = ObligationCtxt::new(&infcx);
let item_ty = ocx.normalize(
&ObligationCause::misc(span, def_id),
param_env,
Ty::new_projection(tcx, assoc_item_def_id, args),
);
// FIXME(compiler-errors): We may benefit from resolving regions here.
if ocx.select_where_possible().is_empty()
&& let item_ty = infcx.resolve_vars_if_possible(item_ty)
&& let Some(item_ty) = item_ty.make_suggestable(tcx, false, None)
&& let Some(sugg) = formatter(
tcx,
infcx.resolve_vars_if_possible(args),
trait_def_id,
assoc_item_def_id,
item_ty,
)
{
return Some(sugg);
if sugg.is_some() {
return sugg;
}
}
None