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Manually register some bounds for a better span
1 parent e4c1a00 commit 97dfe8b

14 files changed

+156
-14
lines changed

‎compiler/rustc_hir_analysis/src/check/check.rs

+37-8
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@ use rustc_errors::codes::*;
88
use rustc_hir::def::{CtorKind, DefKind};
99
use rustc_hir::{Node, intravisit};
1010
use rustc_infer::infer::{RegionVariableOrigin, TyCtxtInferExt};
11-
use rustc_infer::traits::Obligation;
11+
use rustc_infer::traits::{Obligation, ObligationCauseCode};
1212
use rustc_lint_defs::builtin::{
1313
REPR_TRANSPARENT_EXTERNAL_PRIVATE_FIELDS, UNSUPPORTED_FN_PTR_CALLING_CONVENTIONS,
1414
};
@@ -267,7 +267,12 @@ fn check_opaque_meets_bounds<'tcx>(
267267
def_id: LocalDefId,
268268
origin: hir::OpaqueTyOrigin<LocalDefId>,
269269
) -> Result<(), ErrorGuaranteed> {
270-
let span = span_of_opaque(tcx, def_id, origin).unwrap_or_else(|| tcx.def_span(def_id));
270+
let (span, definition_def_id) =
271+
if let Some((span, def_id)) = best_definition_site_of_opaque(tcx, def_id, origin) {
272+
(span, Some(def_id))
273+
} else {
274+
(tcx.def_span(def_id), None)
275+
};
271276

272277
let defining_use_anchor = match origin {
273278
hir::OpaqueTyOrigin::FnReturn { parent, .. }
@@ -305,8 +310,32 @@ fn check_opaque_meets_bounds<'tcx>(
305310
_ => re,
306311
});
307312

308-
let misc_cause = traits::ObligationCause::misc(span, def_id);
313+
// HACK: We eagerly instantiate some bounds to report better errors for them...
314+
// This isn't necessary for correctness, since we register these bounds when
315+
// equating the opaque below, but we should clean this up in the new solver.
316+
for (predicate, pred_span) in
317+
tcx.explicit_item_bounds(def_id).iter_instantiated_copied(tcx, args)
318+
{
319+
let predicate = predicate.fold_with(&mut BottomUpFolder {
320+
tcx,
321+
ty_op: |ty| if ty == opaque_ty { hidden_ty } else { ty },
322+
lt_op: |lt| lt,
323+
ct_op: |ct| ct,
324+
});
325+
326+
ocx.register_obligation(Obligation::new(
327+
tcx,
328+
ObligationCause::new(
329+
span,
330+
def_id,
331+
ObligationCauseCode::OpaqueTypeBound(pred_span, definition_def_id),
332+
),
333+
param_env,
334+
predicate,
335+
));
336+
}
309337

338+
let misc_cause = ObligationCause::misc(span, def_id);
310339
// FIXME: We should just register the item bounds here, rather than equating.
311340
match ocx.eq(&misc_cause, param_env, opaque_ty, hidden_ty) {
312341
Ok(()) => {}
@@ -364,33 +393,33 @@ fn check_opaque_meets_bounds<'tcx>(
364393
}
365394
}
366395

367-
fn span_of_opaque<'tcx>(
396+
fn best_definition_site_of_opaque<'tcx>(
368397
tcx: TyCtxt<'tcx>,
369398
opaque_def_id: LocalDefId,
370399
origin: hir::OpaqueTyOrigin<LocalDefId>,
371-
) -> Option<Span> {
400+
) -> Option<(Span, LocalDefId)> {
372401
struct TaitConstraintLocator<'tcx> {
373402
opaque_def_id: LocalDefId,
374403
tcx: TyCtxt<'tcx>,
375404
}
376405
impl<'tcx> TaitConstraintLocator<'tcx> {
377-
fn check(&self, item_def_id: LocalDefId) -> ControlFlow<Span> {
406+
fn check(&self, item_def_id: LocalDefId) -> ControlFlow<(Span, LocalDefId)> {
378407
if !self.tcx.has_typeck_results(item_def_id) {
379408
return ControlFlow::Continue(());
380409
}
381410

382411
if let Some(hidden_ty) =
383412
self.tcx.mir_borrowck(item_def_id).concrete_opaque_types.get(&self.opaque_def_id)
384413
{
385-
ControlFlow::Break(hidden_ty.span)
414+
ControlFlow::Break((hidden_ty.span, item_def_id))
386415
} else {
387416
ControlFlow::Continue(())
388417
}
389418
}
390419
}
391420
impl<'tcx> intravisit::Visitor<'tcx> for TaitConstraintLocator<'tcx> {
392421
type NestedFilter = nested_filter::All;
393-
type Result = ControlFlow<Span>;
422+
type Result = ControlFlow<(Span, LocalDefId)>;
394423
fn nested_visit_map(&mut self) -> Self::Map {
395424
self.tcx.hir()
396425
}

‎compiler/rustc_infer/src/infer/outlives/obligations.rs

+1
Original file line numberDiff line numberDiff line change
@@ -104,6 +104,7 @@ impl<'tcx> InferCtxt<'tcx> {
104104
infer::RelateParamBound(cause.span, sup_type, match cause.code().peel_derives() {
105105
ObligationCauseCode::WhereClause(_, span)
106106
| ObligationCauseCode::WhereClauseInExpr(_, span, ..)
107+
| ObligationCauseCode::OpaqueTypeBound(span, _)
107108
if !span.is_dummy() =>
108109
{
109110
Some(*span)

‎compiler/rustc_middle/src/traits/mod.rs

+5
Original file line numberDiff line numberDiff line change
@@ -193,6 +193,11 @@ pub enum ObligationCauseCode<'tcx> {
193193
/// The span corresponds to the clause.
194194
WhereClause(DefId, Span),
195195

196+
/// Represents a bound for an opaque we are checking the well-formedness of.
197+
/// The def-id corresponds to a specific definition site that we found the
198+
/// hidden type from, if any.
199+
OpaqueTypeBound(Span, Option<LocalDefId>),
200+
196201
/// Like `WhereClause`, but also identifies the expression
197202
/// which requires the `where` clause to be proven, and also
198203
/// identifies the index of the predicate in the `predicates_of`

‎compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs

+16
Original file line numberDiff line numberDiff line change
@@ -2953,6 +2953,22 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
29532953
// We hold the `DefId` of the item introducing the obligation, but displaying it
29542954
// doesn't add user usable information. It always point at an associated item.
29552955
}
2956+
ObligationCauseCode::OpaqueTypeBound(span, definition_def_id) => {
2957+
err.span_note(span, "required by a bound in an opaque type");
2958+
if let Some(definition_def_id) = definition_def_id
2959+
// If there are any stalled coroutine obligations, then this
2960+
// error may be due to that, and not because the body has more
2961+
// where-clauses.
2962+
&& self.tcx.typeck(definition_def_id).coroutine_stalled_predicates.is_empty()
2963+
{
2964+
// FIXME(compiler-errors): We could probably point to something
2965+
// specific here if we tried hard enough...
2966+
err.span_note(
2967+
tcx.def_span(definition_def_id),
2968+
"this definition site has more where clauses than the opaque type",
2969+
);
2970+
}
2971+
}
29562972
ObligationCauseCode::Coercion { source, target } => {
29572973
let source =
29582974
tcx.short_ty_string(self.resolve_vars_if_possible(source), long_ty_file);

‎tests/ui/async-await/issue-70935-complex-spans.stderr

+5
Original file line numberDiff line numberDiff line change
@@ -35,6 +35,11 @@ note: required because it's used within this `async` block
3535
|
3636
LL | async move {
3737
| ^^^^^^^^^^
38+
note: required by a bound in an opaque type
39+
--> $DIR/issue-70935-complex-spans.rs:15:37
40+
|
41+
LL | fn foo(x: NotSync) -> impl Future + Send {
42+
| ^^^^
3843

3944
error[E0277]: `*mut ()` cannot be shared between threads safely
4045
--> $DIR/issue-70935-complex-spans.rs:15:23

‎tests/ui/type-alias-impl-trait/bounds-are-checked-2.stderr

+10
Original file line numberDiff line numberDiff line change
@@ -4,6 +4,16 @@ error[E0277]: the trait bound `T: Clone` is not satisfied
44
LL | t
55
| ^ the trait `Clone` is not implemented for `T`
66
|
7+
note: required by a bound in an opaque type
8+
--> $DIR/bounds-are-checked-2.rs:7:26
9+
|
10+
LL | pub type X<T> = impl Clone;
11+
| ^^^^^
12+
note: this definition site has more where clauses than the opaque type
13+
--> $DIR/bounds-are-checked-2.rs:9:5
14+
|
15+
LL | fn f<T: Clone>(t: T) -> X<T> {
16+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
717
help: consider restricting type parameter `T`
818
|
919
LL | pub type X<T: std::clone::Clone> = impl Clone;

‎tests/ui/type-alias-impl-trait/generic_duplicate_param_use2.stderr

+10
Original file line numberDiff line numberDiff line change
@@ -4,6 +4,16 @@ error[E0277]: `T` doesn't implement `Debug`
44
LL | t
55
| ^ `T` cannot be formatted using `{:?}` because it doesn't implement `Debug`
66
|
7+
note: required by a bound in an opaque type
8+
--> $DIR/generic_duplicate_param_use2.rs:8:23
9+
|
10+
LL | type Two<T, U> = impl Debug;
11+
| ^^^^^
12+
note: this definition site has more where clauses than the opaque type
13+
--> $DIR/generic_duplicate_param_use2.rs:10:1
14+
|
15+
LL | fn two<T: Debug, U>(t: T, _: U) -> Two<T, U> {
16+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
717
help: consider restricting type parameter `T`
818
|
919
LL | type Two<T: std::fmt::Debug, U> = impl Debug;

‎tests/ui/type-alias-impl-trait/generic_duplicate_param_use4.stderr

+10
Original file line numberDiff line numberDiff line change
@@ -4,6 +4,16 @@ error[E0277]: `U` doesn't implement `Debug`
44
LL | u
55
| ^ `U` cannot be formatted using `{:?}` because it doesn't implement `Debug`
66
|
7+
note: required by a bound in an opaque type
8+
--> $DIR/generic_duplicate_param_use4.rs:8:23
9+
|
10+
LL | type Two<T, U> = impl Debug;
11+
| ^^^^^
12+
note: this definition site has more where clauses than the opaque type
13+
--> $DIR/generic_duplicate_param_use4.rs:10:1
14+
|
15+
LL | fn three<T, U: Debug>(_: T, u: U) -> Two<T, U> {
16+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
717
help: consider restricting type parameter `U`
818
|
919
LL | type Two<T, U: std::fmt::Debug> = impl Debug;

‎tests/ui/type-alias-impl-trait/hidden_type_mismatch.stderr

+14
Original file line numberDiff line numberDiff line change
@@ -21,6 +21,20 @@ LL | impl<T: Proj<Assoc = i32> + Copy> Copy for Bar<T> {}
2121
| ----------- ^^^^ ^^^^^^
2222
| |
2323
| unsatisfied trait bound introduced here
24+
note: required by a bound in an opaque type
25+
--> $DIR/hidden_type_mismatch.rs:36:26
26+
|
27+
LL | pub type Tait = impl Copy + From<Bar<()>> + Into<Bar<()>>;
28+
| ^^^^
29+
note: this definition site has more where clauses than the opaque type
30+
--> $DIR/hidden_type_mismatch.rs:37:5
31+
|
32+
LL | / pub fn define_tait() -> Tait
33+
LL | | where
34+
LL | | // this proves `Bar<()>: Copy`, but `define_tait` is
35+
LL | | // now uncallable
36+
LL | | (): Proj<Assoc = i32>,
37+
| |______________________________^
2438

2539
error: aborting due to 1 previous error
2640

‎tests/ui/type-alias-impl-trait/implied_lifetime_wf_check4_static.stderr

+6-1
Original file line numberDiff line numberDiff line change
@@ -5,8 +5,13 @@ LL | s
55
| ^
66
| |
77
| the parameter type `A` must be valid for the static lifetime...
8-
| ...so that the type `A` will meet its required lifetime bounds
8+
| ...so that the type `A` will meet its required lifetime bounds...
99
|
10+
note: ...that is required by this bound
11+
--> $DIR/implied_lifetime_wf_check4_static.rs:4:35
12+
|
13+
LL | pub type Ty<A> = impl Sized + 'static;
14+
| ^^^^^^^
1015
help: consider adding an explicit lifetime bound
1116
|
1217
LL | pub type Ty<A: 'static> = impl Sized + 'static;

‎tests/ui/type-alias-impl-trait/issue-52843.stderr

+10
Original file line numberDiff line numberDiff line change
@@ -4,6 +4,16 @@ error[E0277]: the trait bound `T: Default` is not satisfied
44
LL | t
55
| ^ the trait `Default` is not implemented for `T`
66
|
7+
note: required by a bound in an opaque type
8+
--> $DIR/issue-52843.rs:3:20
9+
|
10+
LL | type Foo<T> = impl Default;
11+
| ^^^^^^^
12+
note: this definition site has more where clauses than the opaque type
13+
--> $DIR/issue-52843.rs:6:1
14+
|
15+
LL | fn foo<T: Default>(t: T) -> Foo<T> {
16+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
717
help: consider restricting type parameter `T`
818
|
919
LL | type Foo<T: std::default::Default> = impl Default;

‎tests/ui/type-alias-impl-trait/issue-90400-2.stderr

+16-4
Original file line numberDiff line numberDiff line change
@@ -4,11 +4,23 @@ error[E0277]: the trait bound `B: Bar` is not satisfied
44
LL | MyBaz(bar)
55
| ^^^^^^^^^^ the trait `Bar` is not implemented for `B`
66
|
7-
note: required by a bound in `MyBaz`
8-
--> $DIR/issue-90400-2.rs:29:17
7+
note: required for `MyBaz<B>` to implement `Baz`
8+
--> $DIR/issue-90400-2.rs:30:14
99
|
10-
LL | struct MyBaz<B: Bar>(B);
11-
| ^^^ required by this bound in `MyBaz`
10+
LL | impl<B: Bar> Baz for MyBaz<B> {
11+
| --- ^^^ ^^^^^^^^
12+
| |
13+
| unsatisfied trait bound introduced here
14+
note: required by a bound in an opaque type
15+
--> $DIR/issue-90400-2.rs:22:26
16+
|
17+
LL | type FooFn<B> = impl Baz;
18+
| ^^^
19+
note: this definition site has more where clauses than the opaque type
20+
--> $DIR/issue-90400-2.rs:24:5
21+
|
22+
LL | fn foo<B: Bar>(&self, bar: B) -> Self::FooFn<B> {
23+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
1224
help: consider restricting type parameter `B`
1325
|
1426
LL | type FooFn<B: Bar> = impl Baz;

‎tests/ui/type-alias-impl-trait/underconstrained_generic.stderr

+10
Original file line numberDiff line numberDiff line change
@@ -11,6 +11,16 @@ LL | impl<X: Trait> ProofForConversion<X> for () {
1111
| ----- ^^^^^^^^^^^^^^^^^^^^^ ^^
1212
| |
1313
| unsatisfied trait bound introduced here
14+
note: required by a bound in an opaque type
15+
--> $DIR/underconstrained_generic.rs:19:26
16+
|
17+
LL | type Converter<T> = impl ProofForConversion<T>;
18+
| ^^^^^^^^^^^^^^^^^^^^^
19+
note: this definition site has more where clauses than the opaque type
20+
--> $DIR/underconstrained_generic.rs:21:1
21+
|
22+
LL | fn _defining_use<T: Trait>() -> Converter<T> {
23+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
1424
help: consider restricting type parameter `T`
1525
|
1626
LL | type Converter<T: Trait> = impl ProofForConversion<T>;

‎tests/ui/type-alias-impl-trait/wf-in-associated-type.fail.stderr

+6-1
Original file line numberDiff line numberDiff line change
@@ -5,8 +5,13 @@ LL | impl<'a, T> Trait<'a, T> for () {
55
| -- the parameter type `T` must be valid for the lifetime `'a` as defined here...
66
...
77
LL | req
8-
| ^^^ ...so that the type `&'a T` will meet its required lifetime bounds
8+
| ^^^ ...so that the type `&'a T` will meet its required lifetime bounds...
99
|
10+
note: ...that is required by this bound
11+
--> $DIR/wf-in-associated-type.rs:38:36
12+
|
13+
LL | type Opaque = impl Sized + 'a;
14+
| ^^
1015
help: consider adding an explicit lifetime bound
1116
|
1217
LL | impl<'a, T: 'a> Trait<'a, T> for () {

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