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Refactor FulfillmentError to track less data
Move the information about pointing at the call argument expression in an unmet obligation span from the `FulfillmentError` to a new `ObligationCauseCode`.
1 parent 284a8a9 commit 8a3f712

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11 files changed

+86
-57
lines changed

11 files changed

+86
-57
lines changed

‎compiler/rustc_borrowck/src/type_check/mod.rs

Lines changed: 0 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1998,7 +1998,6 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
19981998
&obligation,
19991999
&traits::SelectionError::Unimplemented,
20002000
false,
2001-
false,
20022001
);
20032002
}
20042003
}

‎compiler/rustc_infer/src/infer/error_reporting/nice_region_error/mismatched_static_lifetime.rs

Lines changed: 7 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -29,7 +29,13 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
2929
SubregionOrigin::Subtype(box TypeTrace { ref cause, .. }) => cause,
3030
_ => return None,
3131
};
32-
let (parent, impl_def_id) = match &cause.code {
32+
// If we added a "points at argument expression" obligation, we remove it here, we care
33+
// about the original obligation only.
34+
let code = match &cause.code {
35+
ObligationCauseCode::FunctionArgumentObligation { parent_code, .. } => &*parent_code,
36+
_ => &cause.code,
37+
};
38+
let (parent, impl_def_id) = match code {
3339
ObligationCauseCode::MatchImpl(parent, impl_def_id) => (parent, impl_def_id),
3440
_ => return None,
3541
};

‎compiler/rustc_infer/src/traits/mod.rs

Lines changed: 1 addition & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -66,10 +66,6 @@ pub type Selection<'tcx> = ImplSource<'tcx, PredicateObligation<'tcx>>;
6666
pub struct FulfillmentError<'tcx> {
6767
pub obligation: PredicateObligation<'tcx>,
6868
pub code: FulfillmentErrorCode<'tcx>,
69-
/// Diagnostics only: we opportunistically change the `code.span` when we encounter an
70-
/// obligation error caused by a call argument. When this is the case, we also signal that in
71-
/// this field to ensure accuracy of suggestions.
72-
pub points_at_arg_span: bool,
7369
/// Diagnostics only: the 'root' obligation which resulted in
7470
/// the failure to process `obligation`. This is the obligation
7571
/// that was initially passed to `register_predicate_obligation`
@@ -128,7 +124,7 @@ impl<'tcx> FulfillmentError<'tcx> {
128124
code: FulfillmentErrorCode<'tcx>,
129125
root_obligation: PredicateObligation<'tcx>,
130126
) -> FulfillmentError<'tcx> {
131-
FulfillmentError { obligation, code, points_at_arg_span: false, root_obligation }
127+
FulfillmentError { obligation, code, root_obligation }
132128
}
133129
}
134130

‎compiler/rustc_middle/src/traits/mod.rs

Lines changed: 14 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -253,6 +253,15 @@ pub enum ObligationCauseCode<'tcx> {
253253

254254
DerivedObligation(DerivedObligationCause<'tcx>),
255255

256+
FunctionArgumentObligation {
257+
/// The node of the relevant argument in the function call.
258+
arg_hir_id: hir::HirId,
259+
/// The node of the function call.
260+
call_hir_id: hir::HirId,
261+
/// The obligation introduced by this argument.
262+
parent_code: Lrc<ObligationCauseCode<'tcx>>,
263+
},
264+
256265
/// Error derived when matching traits/impls; see ObligationCause for more details
257266
CompareImplConstObligation,
258267

@@ -368,11 +377,12 @@ impl ObligationCauseCode<'_> {
368377
// Return the base obligation, ignoring derived obligations.
369378
pub fn peel_derives(&self) -> &Self {
370379
let mut base_cause = self;
371-
while let BuiltinDerivedObligation(cause)
372-
| ImplDerivedObligation(cause)
373-
| DerivedObligation(cause) = base_cause
380+
while let BuiltinDerivedObligation(DerivedObligationCause { parent_code, .. })
381+
| ImplDerivedObligation(DerivedObligationCause { parent_code, .. })
382+
| DerivedObligation(DerivedObligationCause { parent_code, .. })
383+
| FunctionArgumentObligation { parent_code, .. } = base_cause
374384
{
375-
base_cause = &cause.parent_code;
385+
base_cause = &parent_code;
376386
}
377387
base_cause
378388
}

‎compiler/rustc_trait_selection/src/traits/chalk_fulfill.rs

Lines changed: 0 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -57,7 +57,6 @@ impl TraitEngine<'tcx> for FulfillmentContext<'tcx> {
5757
.map(|obligation| FulfillmentError {
5858
obligation: obligation.clone(),
5959
code: FulfillmentErrorCode::CodeAmbiguity,
60-
points_at_arg_span: false,
6160
// FIXME - does Chalk have a notation of 'root obligation'?
6261
// This is just for diagnostics, so it's okay if this is wrong
6362
root_obligation: obligation.clone(),
@@ -112,7 +111,6 @@ impl TraitEngine<'tcx> for FulfillmentContext<'tcx> {
112111
code: FulfillmentErrorCode::CodeSelectionError(
113112
SelectionError::Unimplemented,
114113
),
115-
points_at_arg_span: false,
116114
// FIXME - does Chalk have a notation of 'root obligation'?
117115
// This is just for diagnostics, so it's okay if this is wrong
118116
root_obligation: obligation,
@@ -129,7 +127,6 @@ impl TraitEngine<'tcx> for FulfillmentContext<'tcx> {
129127
code: FulfillmentErrorCode::CodeSelectionError(
130128
SelectionError::Unimplemented,
131129
),
132-
points_at_arg_span: false,
133130
// FIXME - does Chalk have a notation of 'root obligation'?
134131
// This is just for diagnostics, so it's okay if this is wrong
135132
root_obligation: obligation,

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

Lines changed: 3 additions & 12 deletions
Original file line numberDiff line numberDiff line change
@@ -66,7 +66,6 @@ pub trait InferCtxtExt<'tcx> {
6666
root_obligation: &PredicateObligation<'tcx>,
6767
error: &SelectionError<'tcx>,
6868
fallback_has_occurred: bool,
69-
points_at_arg: bool,
7069
);
7170

7271
/// Given some node representing a fn-like thing in the HIR map,
@@ -237,7 +236,6 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
237236
root_obligation: &PredicateObligation<'tcx>,
238237
error: &SelectionError<'tcx>,
239238
fallback_has_occurred: bool,
240-
points_at_arg: bool,
241239
) {
242240
let tcx = self.tcx;
243241
let mut span = obligation.cause.span;
@@ -387,7 +385,6 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
387385
&obligation,
388386
&mut err,
389387
&trait_ref,
390-
points_at_arg,
391388
have_alt_message,
392389
) {
393390
self.note_obligation_cause(&mut err, &obligation);
@@ -430,8 +427,8 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
430427
err.span_label(enclosing_scope_span, s.as_str());
431428
}
432429

433-
self.suggest_dereferences(&obligation, &mut err, trait_ref, points_at_arg);
434-
self.suggest_fn_call(&obligation, &mut err, trait_ref, points_at_arg);
430+
self.suggest_dereferences(&obligation, &mut err, trait_ref);
431+
self.suggest_fn_call(&obligation, &mut err, trait_ref);
435432
self.suggest_remove_reference(&obligation, &mut err, trait_ref);
436433
self.suggest_semicolon_removal(&obligation, &mut err, span, trait_ref);
437434
self.note_version_mismatch(&mut err, &trait_ref);
@@ -500,12 +497,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
500497
// Changing mutability doesn't make a difference to whether we have
501498
// an `Unsize` impl (Fixes ICE in #71036)
502499
if !is_unsize {
503-
self.suggest_change_mut(
504-
&obligation,
505-
&mut err,
506-
trait_ref,
507-
points_at_arg,
508-
);
500+
self.suggest_change_mut(&obligation, &mut err, trait_ref);
509501
}
510502

511503
// If this error is due to `!: Trait` not implemented but `(): Trait` is
@@ -1214,7 +1206,6 @@ impl<'a, 'tcx> InferCtxtPrivExt<'tcx> for InferCtxt<'a, 'tcx> {
12141206
&error.root_obligation,
12151207
selection_error,
12161208
fallback_has_occurred,
1217-
error.points_at_arg_span,
12181209
);
12191210
}
12201211
FulfillmentErrorCode::CodeProjectionError(ref e) => {

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

Lines changed: 40 additions & 19 deletions
Original file line numberDiff line numberDiff line change
@@ -54,7 +54,6 @@ pub trait InferCtxtExt<'tcx> {
5454
obligation: &PredicateObligation<'tcx>,
5555
err: &mut DiagnosticBuilder<'tcx>,
5656
trait_ref: ty::PolyTraitRef<'tcx>,
57-
points_at_arg: bool,
5857
);
5958

6059
fn get_closure_name(
@@ -69,15 +68,13 @@ pub trait InferCtxtExt<'tcx> {
6968
obligation: &PredicateObligation<'tcx>,
7069
err: &mut DiagnosticBuilder<'_>,
7170
trait_ref: ty::Binder<'tcx, ty::TraitRef<'tcx>>,
72-
points_at_arg: bool,
7371
);
7472

7573
fn suggest_add_reference_to_arg(
7674
&self,
7775
obligation: &PredicateObligation<'tcx>,
7876
err: &mut DiagnosticBuilder<'_>,
7977
trait_ref: &ty::Binder<'tcx, ty::TraitRef<'tcx>>,
80-
points_at_arg: bool,
8178
has_custom_message: bool,
8279
) -> bool;
8380

@@ -93,7 +90,6 @@ pub trait InferCtxtExt<'tcx> {
9390
obligation: &PredicateObligation<'tcx>,
9491
err: &mut DiagnosticBuilder<'_>,
9592
trait_ref: ty::Binder<'tcx, ty::TraitRef<'tcx>>,
96-
points_at_arg: bool,
9793
);
9894

9995
fn suggest_semicolon_removal(
@@ -490,16 +486,19 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
490486
obligation: &PredicateObligation<'tcx>,
491487
err: &mut DiagnosticBuilder<'tcx>,
492488
trait_ref: ty::PolyTraitRef<'tcx>,
493-
points_at_arg: bool,
494489
) {
495490
// It only make sense when suggesting dereferences for arguments
496-
if !points_at_arg {
491+
let code = if let ObligationCauseCode::FunctionArgumentObligation { parent_code, .. } =
492+
&obligation.cause.code
493+
{
494+
std::rc::Rc::clone(parent_code)
495+
} else {
497496
return;
498-
}
497+
};
499498
let param_env = obligation.param_env;
500499
let body_id = obligation.cause.body_id;
501500
let span = obligation.cause.span;
502-
let real_trait_ref = match &obligation.cause.code {
501+
let real_trait_ref = match &*code {
503502
ObligationCauseCode::ImplDerivedObligation(cause)
504503
| ObligationCauseCode::DerivedObligation(cause)
505504
| ObligationCauseCode::BuiltinDerivedObligation(cause) => cause.parent_trait_ref,
@@ -584,7 +583,6 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
584583
obligation: &PredicateObligation<'tcx>,
585584
err: &mut DiagnosticBuilder<'_>,
586585
trait_ref: ty::Binder<'tcx, ty::TraitRef<'tcx>>,
587-
points_at_arg: bool,
588586
) {
589587
let self_ty = match trait_ref.self_ty().no_bound_vars() {
590588
None => return,
@@ -656,11 +654,11 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
656654
}
657655
_ => return,
658656
};
659-
if points_at_arg {
657+
if matches!(obligation.cause.code, ObligationCauseCode::FunctionArgumentObligation { .. }) {
660658
// When the obligation error has been ensured to have been caused by
661659
// an argument, the `obligation.cause.span` points at the expression
662-
// of the argument, so we can provide a suggestion. This is signaled
663-
// by `points_at_arg`. Otherwise, we give a more general note.
660+
// of the argument, so we can provide a suggestion. Otherwise, we give
661+
// a more general note.
664662
err.span_suggestion_verbose(
665663
obligation.cause.span.shrink_to_hi(),
666664
&msg,
@@ -677,7 +675,6 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
677675
obligation: &PredicateObligation<'tcx>,
678676
err: &mut DiagnosticBuilder<'_>,
679677
trait_ref: &ty::Binder<'tcx, ty::TraitRef<'tcx>>,
680-
points_at_arg: bool,
681678
has_custom_message: bool,
682679
) -> bool {
683680
let span = obligation.cause.span;
@@ -686,9 +683,14 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
686683
ExpnKind::Desugaring(DesugaringKind::ForLoop(ForLoopLoc::IntoIter))
687684
);
688685

689-
if !points_at_arg && !points_at_for_iter {
690-
return false;
691-
}
686+
let code =
687+
if let (ObligationCauseCode::FunctionArgumentObligation { parent_code, .. }, false) =
688+
(&obligation.cause.code, points_at_for_iter)
689+
{
690+
std::rc::Rc::clone(parent_code)
691+
} else {
692+
return false;
693+
};
692694

693695
// List of traits for which it would be nonsensical to suggest borrowing.
694696
// For instance, immutable references are always Copy, so suggesting to
@@ -787,7 +789,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
787789
return false;
788790
};
789791

790-
if let ObligationCauseCode::ImplDerivedObligation(obligation) = &obligation.cause.code {
792+
if let ObligationCauseCode::ImplDerivedObligation(obligation) = &*code {
791793
let expected_trait_ref = obligation.parent_trait_ref.skip_binder();
792794
let new_imm_trait_ref =
793795
ty::TraitRef::new(obligation.parent_trait_ref.def_id(), imm_substs);
@@ -799,7 +801,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
799801
return try_borrowing(new_mut_trait_ref, expected_trait_ref, true, &[]);
800802
}
801803
} else if let ObligationCauseCode::BindingObligation(_, _)
802-
| ObligationCauseCode::ItemObligation(_) = &obligation.cause.code
804+
| ObligationCauseCode::ItemObligation(_) = &*code
803805
{
804806
if try_borrowing(
805807
ty::TraitRef::new(trait_ref.def_id, imm_substs),
@@ -891,8 +893,12 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
891893
obligation: &PredicateObligation<'tcx>,
892894
err: &mut DiagnosticBuilder<'_>,
893895
trait_ref: ty::Binder<'tcx, ty::TraitRef<'tcx>>,
894-
points_at_arg: bool,
895896
) {
897+
let points_at_arg = matches!(
898+
obligation.cause.code,
899+
ObligationCauseCode::FunctionArgumentObligation { .. },
900+
);
901+
896902
let span = obligation.cause.span;
897903
if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span) {
898904
let refs_number =
@@ -2289,6 +2295,21 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
22892295
)
22902296
});
22912297
}
2298+
ObligationCauseCode::FunctionArgumentObligation {
2299+
arg_hir_id: _,
2300+
call_hir_id: _,
2301+
ref parent_code,
2302+
} => {
2303+
ensure_sufficient_stack(|| {
2304+
self.note_obligation_cause_code(
2305+
err,
2306+
predicate,
2307+
&parent_code,
2308+
obligated_types,
2309+
seen_requirements,
2310+
)
2311+
});
2312+
}
22922313
ObligationCauseCode::CompareImplMethodObligation {
22932314
item_name,
22942315
trait_item_def_id,

‎compiler/rustc_typeck/src/check/coercion.rs

Lines changed: 1 addition & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -707,13 +707,7 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
707707

708708
// Object safety violations or miscellaneous.
709709
Err(err) => {
710-
self.report_selection_error(
711-
obligation.clone(),
712-
&obligation,
713-
&err,
714-
false,
715-
false,
716-
);
710+
self.report_selection_error(obligation.clone(), &obligation, &err, false);
717711
// Treat this like an obligation and follow through
718712
// with the unsizing - the lack of a coercion should
719713
// be silent, as it causes a type mismatch later.

‎compiler/rustc_typeck/src/check/fn_ctxt/checks.rs

Lines changed: 17 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -9,6 +9,7 @@ use crate::check::{
99
};
1010

1111
use rustc_ast as ast;
12+
use rustc_data_structures::sync::Lrc;
1213
use rustc_errors::{Applicability, DiagnosticBuilder, DiagnosticId};
1314
use rustc_hir as hir;
1415
use rustc_hir::def::{CtorOf, DefKind, Res};
@@ -324,6 +325,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
324325
self.point_at_arg_instead_of_call_if_possible(
325326
errors,
326327
&final_arg_types[..],
328+
expr,
327329
sp,
328330
&args,
329331
);
@@ -391,7 +393,13 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
391393
) {
392394
for error in errors {
393395
error.obligation.cause.make_mut().span = arg.span;
394-
error.points_at_arg_span = true;
396+
let code = error.obligation.cause.code.clone();
397+
error.obligation.cause.make_mut().code =
398+
ObligationCauseCode::FunctionArgumentObligation {
399+
arg_hir_id: arg.hir_id,
400+
call_hir_id: expr.hir_id,
401+
parent_code: Lrc::new(code),
402+
};
395403
}
396404
}
397405
},
@@ -937,6 +945,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
937945
&self,
938946
errors: &mut Vec<traits::FulfillmentError<'tcx>>,
939947
final_arg_types: &[(usize, Ty<'tcx>, Ty<'tcx>)],
948+
expr: &'tcx hir::Expr<'tcx>,
940949
call_sp: Span,
941950
args: &'tcx [hir::Expr<'tcx>],
942951
) {
@@ -986,7 +995,13 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
986995
// We make sure that only *one* argument matches the obligation failure
987996
// and we assign the obligation's span to its expression's.
988997
error.obligation.cause.make_mut().span = args[ref_in].span;
989-
error.points_at_arg_span = true;
998+
let code = error.obligation.cause.code.clone();
999+
error.obligation.cause.make_mut().code =
1000+
ObligationCauseCode::FunctionArgumentObligation {
1001+
arg_hir_id: args[ref_in].hir_id,
1002+
call_hir_id: expr.hir_id,
1003+
parent_code: Lrc::new(code),
1004+
};
9901005
}
9911006
}
9921007
}

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