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diagnostics: use `DeepRejectCtxt` for check 

This makes more things match, particularly applicable blankets.
This commit is contained in:
Michael Howell 2024-08-13 09:33:12 -07:00
parent 3312f5d652
commit c6fb0f344e
3 changed files with 32 additions and 9 deletions
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37
compiler/rustc_trait_selection/src/error_reporting/infer/note_and_explain.rs
View File

@ -4,6 +4,7 @@ use rustc_hir as hir;
use rustc_hir::def::DefKind;
use rustc_middle::traits::{ObligationCause, ObligationCauseCode};
use rustc_middle::ty::error::{ExpectedFound, TypeError};
use rustc_middle::ty::fast_reject::{DeepRejectCtxt, TreatParams};
use rustc_middle::ty::print::{FmtPrinter, Printer};
use rustc_middle::ty::{self, suggest_constraining_type_param, Ty};
use rustc_span::def_id::DefId;
@ -313,9 +314,15 @@ impl<T> Trait<T> for X {
(ty::Dynamic(t, _, ty::DynKind::Dyn), _)
if let Some(def_id) = t.principal_def_id() =>
{
let has_non_blanket_impl =
tcx.non_blanket_impls_for_ty(def_id, values.found).next().is_some();
if has_non_blanket_impl {
let mut has_matching_impl = false;
tcx.for_each_relevant_impl(def_id, values.found, |did| {
if DeepRejectCtxt::new(tcx, TreatParams::ForLookup)
.types_may_unify(values.found, tcx.type_of(did).skip_binder())
{
has_matching_impl = true;
}
});
if has_matching_impl {
let trait_name = tcx.item_name(def_id);
diag.help(format!(
"`{}` implements `{trait_name}` so you could box the found value \
@ -328,9 +335,15 @@ impl<T> Trait<T> for X {
(_, ty::Dynamic(t, _, ty::DynKind::Dyn))
if let Some(def_id) = t.principal_def_id() =>
{
let has_non_blanket_impl =
tcx.non_blanket_impls_for_ty(def_id, values.expected).next().is_some();
if has_non_blanket_impl {
let mut has_matching_impl = false;
tcx.for_each_relevant_impl(def_id, values.expected, |did| {
if DeepRejectCtxt::new(tcx, TreatParams::ForLookup)
.types_may_unify(values.expected, tcx.type_of(did).skip_binder())
{
has_matching_impl = true;
}
});
if has_matching_impl {
let trait_name = tcx.item_name(def_id);
diag.help(format!(
"`{}` implements `{trait_name}` so you could change the expected \
@ -342,9 +355,15 @@ impl<T> Trait<T> for X {
(ty::Dynamic(t, _, ty::DynKind::DynStar), _)
if let Some(def_id) = t.principal_def_id() =>
{
let has_non_blanket_impl =
tcx.non_blanket_impls_for_ty(def_id, values.found).next().is_some();
if has_non_blanket_impl {
let mut has_matching_impl = false;
tcx.for_each_relevant_impl(def_id, values.found, |did| {
if DeepRejectCtxt::new(tcx, TreatParams::ForLookup)
.types_may_unify(values.found, tcx.type_of(did).skip_binder())
{
has_matching_impl = true;
}
});
if has_matching_impl {
let trait_name = tcx.item_name(def_id);
diag.help(format!(
"`{}` implements `{trait_name}`, `#[feature(dyn_star)]` is likely \

3
tests/ui/cast/ptr-to-trait-obj-different-args.stderr
View File

@ -14,6 +14,7 @@ LL | let y: *const dyn Trait<Y> = x as _;
|
= note: expected trait object `dyn Trait<X>`
found trait object `dyn Trait<Y>`
= help: `dyn Trait<Y>` implements `Trait` so you could box the found value and coerce it to the trait object `Box<dyn Trait>`, you will have to change the expected type as well
error[E0308]: mismatched types
--> $DIR/ptr-to-trait-obj-different-args.rs:27:34
@ -25,6 +26,7 @@ LL | let _: *const dyn Trait<T> = x as _;
|
= note: expected trait object `dyn Trait<X>`
found trait object `dyn Trait<T>`
= help: `dyn Trait<T>` implements `Trait` so you could box the found value and coerce it to the trait object `Box<dyn Trait>`, you will have to change the expected type as well
error[E0308]: mismatched types
--> $DIR/ptr-to-trait-obj-different-args.rs:28:34
@ -37,6 +39,7 @@ LL | let _: *const dyn Trait<X> = t as _;
|
= note: expected trait object `dyn Trait<T>`
found trait object `dyn Trait<X>`
= help: `dyn Trait<X>` implements `Trait` so you could box the found value and coerce it to the trait object `Box<dyn Trait>`, you will have to change the expected type as well
error[E0308]: mismatched types
--> $DIR/ptr-to-trait-obj-different-args.rs:36:5

1
tests/ui/traits/upcast_soundness_bug.stderr
View File

@ -6,6 +6,7 @@ LL | let p = p as *const dyn Trait<u8, u16>; // <- this is bad!
|
= note: expected trait object `dyn Trait<u8, u8>`
found trait object `dyn Trait<u8, u16>`
= help: `dyn Trait<u8, u16>` implements `Trait` so you could box the found value and coerce it to the trait object `Box<dyn Trait>`, you will have to change the expected type as well
error: aborting due to 1 previous error