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Harmonize use of leaf and root obligation in trait error reporting

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This commit is contained in:
Michael Goulet 2024-06-08 14:02:01 -04:00
parent 8337ba9189
commit c453c82de4
12 changed files with 74 additions and 64 deletions
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106
compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs
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@ -412,8 +412,8 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
let bound_predicate = obligation.predicate.kind();
match bound_predicate.skip_binder() {
ty::PredicateKind::Clause(ty::ClauseKind::Trait(trait_predicate)) => {
let trait_predicate = bound_predicate.rebind(trait_predicate);
let trait_predicate = self.resolve_vars_if_possible(trait_predicate);
let leaf_trait_predicate =
self.resolve_vars_if_possible(bound_predicate.rebind(trait_predicate));
// Let's use the root obligation as the main message, when we care about the
// most general case ("X doesn't implement Pattern<'_>") over the case that
@ -424,7 +424,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
let (main_trait_predicate, o) = if let ty::PredicateKind::Clause(
ty::ClauseKind::Trait(root_pred)
) = root_obligation.predicate.kind().skip_binder()
&& !trait_predicate.self_ty().skip_binder().has_escaping_bound_vars()
&& !leaf_trait_predicate.self_ty().skip_binder().has_escaping_bound_vars()
&& !root_pred.self_ty().has_escaping_bound_vars()
// The type of the leaf predicate is (roughly) the same as the type
// from the root predicate, as a proxy for "we care about the root"
@ -434,20 +434,20 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
// `T: Trait` && `&&T: OtherTrait`, we want `OtherTrait`
self.can_eq(
obligation.param_env,
trait_predicate.self_ty().skip_binder(),
leaf_trait_predicate.self_ty().skip_binder(),
root_pred.self_ty().peel_refs(),
)
// `&str: Iterator` && `&str: IntoIterator`, we want `IntoIterator`
|| self.can_eq(
obligation.param_env,
trait_predicate.self_ty().skip_binder(),
leaf_trait_predicate.self_ty().skip_binder(),
root_pred.self_ty(),
)
)
// The leaf trait and the root trait are different, so as to avoid
// talking about `&mut T: Trait` and instead remain talking about
// `T: Trait` instead
&& trait_predicate.def_id() != root_pred.def_id()
&& leaf_trait_predicate.def_id() != root_pred.def_id()
// The root trait is not `Unsize`, as to avoid talking about it in
// `tests/ui/coercion/coerce-issue-49593-box-never.rs`.
&& Some(root_pred.def_id()) != self.tcx.lang_items().unsize_trait()
@ -459,13 +459,14 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
root_obligation,
)
} else {
(trait_predicate, &obligation)
(leaf_trait_predicate, &obligation)
};
let trait_ref = main_trait_predicate.to_poly_trait_ref();
let main_trait_ref = main_trait_predicate.to_poly_trait_ref();
let leaf_trait_ref = leaf_trait_predicate.to_poly_trait_ref();
if let Some(guar) = self.emit_specialized_closure_kind_error(
&obligation,
trait_ref,
leaf_trait_ref,
) {
return guar;
}
@ -473,7 +474,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
// FIXME(effects)
let predicate_is_const = false;
if let Err(guar) = trait_predicate.error_reported()
if let Err(guar) = leaf_trait_predicate.error_reported()
{
return guar;
}
@ -507,16 +508,17 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
notes,
parent_label,
append_const_msg,
} = self.on_unimplemented_note(trait_ref, o, &mut long_ty_file);
} = self.on_unimplemented_note(main_trait_ref, o, &mut long_ty_file);
let have_alt_message = message.is_some() || label.is_some();
let is_try_conversion = self.is_try_conversion(span, trait_ref.def_id());
let is_try_conversion = self.is_try_conversion(span, main_trait_ref.def_id());
let is_unsize =
Some(trait_ref.def_id()) == self.tcx.lang_items().unsize_trait();
Some(leaf_trait_ref.def_id()) == self.tcx.lang_items().unsize_trait();
let (message, notes, append_const_msg) = if is_try_conversion {
(
Some(format!(
"`?` couldn't convert the error to `{}`",
trait_ref.skip_binder().self_ty(),
main_trait_ref.skip_binder().self_ty(),
)),
vec![
"the question mark operation (`?`) implicitly performs a \
@ -537,13 +539,13 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
post_message,
);
let (err_msg, safe_transmute_explanation) = if Some(trait_ref.def_id())
let (err_msg, safe_transmute_explanation) = if Some(main_trait_ref.def_id())
== self.tcx.lang_items().transmute_trait()
{
// Recompute the safe transmute reason and use that for the error reporting
match self.get_safe_transmute_error_and_reason(
obligation.clone(),
trait_ref,
main_trait_ref,
span,
) {
GetSafeTransmuteErrorAndReason::Silent => {
@ -571,7 +573,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
}
let mut suggested = false;
if is_try_conversion {
suggested = self.try_conversion_context(&obligation, trait_ref.skip_binder(), &mut err);
suggested = self.try_conversion_context(&obligation, main_trait_ref.skip_binder(), &mut err);
}
if is_try_conversion && let Some(ret_span) = self.return_type_span(&obligation) {
@ -579,19 +581,19 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
ret_span,
format!(
"expected `{}` because of this",
trait_ref.skip_binder().self_ty()
main_trait_ref.skip_binder().self_ty()
),
);
}
if Some(trait_ref.def_id()) == tcx.lang_items().tuple_trait() {
if Some(leaf_trait_ref.def_id()) == tcx.lang_items().tuple_trait() {
self.add_tuple_trait_message(
obligation.cause.code().peel_derives(),
&mut err,
);
}
if Some(trait_ref.def_id()) == tcx.lang_items().drop_trait()
if Some(leaf_trait_ref.def_id()) == tcx.lang_items().drop_trait()
&& predicate_is_const
{
err.note("`~const Drop` was renamed to `~const Destruct`");
@ -601,15 +603,15 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
let explanation = get_explanation_based_on_obligation(
self.tcx,
&obligation,
trait_ref,
&trait_predicate,
leaf_trait_ref,
&leaf_trait_predicate,
pre_message,
);
self.check_for_binding_assigned_block_without_tail_expression(
&obligation,
&mut err,
trait_predicate,
leaf_trait_predicate,
);
self.suggest_add_result_as_return_type(&obligation,
&mut err,
@ -618,7 +620,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
if self.suggest_add_reference_to_arg(
&obligation,
&mut err,
trait_predicate,
leaf_trait_predicate,
have_alt_message,
) {
self.note_obligation_cause(&mut err, &obligation);
@ -630,7 +632,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
// If it has a custom `#[rustc_on_unimplemented]`
// error message, let's display it as the label!
err.span_label(span, s);
if !matches!(trait_ref.skip_binder().self_ty().kind(), ty::Param(_)) {
if !matches!(leaf_trait_ref.skip_binder().self_ty().kind(), ty::Param(_)) {
// When the self type is a type param We don't need to "the trait
// `std::marker::Sized` is not implemented for `T`" as we will point
// at the type param with a label to suggest constraining it.
@ -645,7 +647,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
if let ObligationCauseCode::Coercion { source, target } =
*obligation.cause.code().peel_derives()
{
if Some(trait_ref.def_id()) == self.tcx.lang_items().sized_trait() {
if Some(leaf_trait_ref.def_id()) == self.tcx.lang_items().sized_trait() {
self.suggest_borrowing_for_object_cast(
&mut err,
root_obligation,
@ -657,7 +659,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
let UnsatisfiedConst(unsatisfied_const) = self
.maybe_add_note_for_unsatisfied_const(
&trait_predicate,
&leaf_trait_predicate,
&mut err,
span,
);
@ -674,15 +676,15 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
err.span_label(tcx.def_span(body), s);
}
self.suggest_floating_point_literal(&obligation, &mut err, &trait_ref);
self.suggest_dereferencing_index(&obligation, &mut err, trait_predicate);
suggested |= self.suggest_dereferences(&obligation, &mut err, trait_predicate);
suggested |= self.suggest_fn_call(&obligation, &mut err, trait_predicate);
let impl_candidates = self.find_similar_impl_candidates(trait_predicate);
self.suggest_floating_point_literal(&obligation, &mut err, &leaf_trait_ref);
self.suggest_dereferencing_index(&obligation, &mut err, leaf_trait_predicate);
suggested |= self.suggest_dereferences(&obligation, &mut err, leaf_trait_predicate);
suggested |= self.suggest_fn_call(&obligation, &mut err, leaf_trait_predicate);
let impl_candidates = self.find_similar_impl_candidates(leaf_trait_predicate);
suggested = if let &[cand] = &impl_candidates[..] {
let cand = cand.trait_ref;
if let (ty::FnPtr(_), ty::FnDef(..)) =
(cand.self_ty().kind(), trait_ref.self_ty().skip_binder().kind())
(cand.self_ty().kind(), main_trait_ref.self_ty().skip_binder().kind())
{
err.span_suggestion(
span.shrink_to_hi(),
@ -702,31 +704,31 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
false
} || suggested;
suggested |=
self.suggest_remove_reference(&obligation, &mut err, trait_predicate);
self.suggest_remove_reference(&obligation, &mut err, leaf_trait_predicate);
suggested |= self.suggest_semicolon_removal(
&obligation,
&mut err,
span,
trait_predicate,
leaf_trait_predicate,
);
self.note_version_mismatch(&mut err, &trait_ref);
self.note_version_mismatch(&mut err, &leaf_trait_ref);
self.suggest_remove_await(&obligation, &mut err);
self.suggest_derive(&obligation, &mut err, trait_predicate);
self.suggest_derive(&obligation, &mut err, leaf_trait_predicate);
if Some(trait_ref.def_id()) == tcx.lang_items().try_trait() {
if Some(leaf_trait_ref.def_id()) == tcx.lang_items().try_trait() {
self.suggest_await_before_try(
&mut err,
&obligation,
trait_predicate,
leaf_trait_predicate,
span,
);
}
if self.suggest_add_clone_to_arg(&obligation, &mut err, trait_predicate) {
if self.suggest_add_clone_to_arg(&obligation, &mut err, leaf_trait_predicate) {
return err.emit();
}
if self.suggest_impl_trait(&mut err, &obligation, trait_predicate) {
if self.suggest_impl_trait(&mut err, &obligation, leaf_trait_predicate) {
return err.emit();
}
@ -741,9 +743,9 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
);
}
let is_fn_trait = tcx.is_fn_trait(trait_ref.def_id());
let is_fn_trait = tcx.is_fn_trait(leaf_trait_ref.def_id());
let is_target_feature_fn = if let ty::FnDef(def_id, _) =
*trait_ref.skip_binder().self_ty().kind()
*leaf_trait_ref.skip_binder().self_ty().kind()
{
!self.tcx.codegen_fn_attrs(def_id).target_features.is_empty()
} else {
@ -757,8 +759,8 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
self.try_to_add_help_message(
&obligation,
trait_ref,
&trait_predicate,
leaf_trait_ref,
&leaf_trait_predicate,
&mut err,
span,
is_fn_trait,
@ -769,17 +771,17 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
// Changing mutability doesn't make a difference to whether we have
// an `Unsize` impl (Fixes ICE in #71036)
if !is_unsize {
self.suggest_change_mut(&obligation, &mut err, trait_predicate);
self.suggest_change_mut(&obligation, &mut err, leaf_trait_predicate);
}
// If this error is due to `!: Trait` not implemented but `(): Trait` is
// implemented, and fallback has occurred, then it could be due to a
// variable that used to fallback to `()` now falling back to `!`. Issue a
// note informing about the change in behaviour.
if trait_predicate.skip_binder().self_ty().is_never()
if leaf_trait_predicate.skip_binder().self_ty().is_never()
&& self.fallback_has_occurred
{
let predicate = trait_predicate.map_bound(|trait_pred| {
let predicate = leaf_trait_predicate.map_bound(|trait_pred| {
trait_pred.with_self_ty(self.tcx, tcx.types.unit)
});
let unit_obligation = obligation.with(tcx, predicate);
@ -794,8 +796,8 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
}
}
self.explain_hrtb_projection(&mut err, trait_predicate, obligation.param_env, &obligation.cause);
self.suggest_desugaring_async_fn_in_trait(&mut err, trait_ref);
self.explain_hrtb_projection(&mut err, leaf_trait_predicate, obligation.param_env, &obligation.cause);
self.suggest_desugaring_async_fn_in_trait(&mut err, main_trait_ref);
// Return early if the trait is Debug or Display and the invocation
// originates within a standard library macro, because the output
@ -813,15 +815,13 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
if in_std_macro
&& matches!(
self.tcx.get_diagnostic_name(trait_ref.def_id()),
self.tcx.get_diagnostic_name(leaf_trait_ref.def_id()),
Some(sym::Debug | sym::Display)
)
{
return err.emit();
}
err
}