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Refactor FulfillmentError to track less data

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Move the information about pointing at the call argument expression in
an unmet obligation span from the `FulfillmentError` to a new
`ObligationCauseCode`.
This commit is contained in:
Esteban Kuber 2021-09-07 11:19:57 +00:00
parent 284a8a9ce7
commit 8a3f712518
11 changed files with 86 additions and 57 deletions
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1
compiler/rustc_borrowck/src/type_check/mod.rs
View File

@ -1998,7 +1998,6 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
&obligation,
&traits::SelectionError::Unimplemented,
false,
false,
);
}
}

8
compiler/rustc_infer/src/infer/error_reporting/nice_region_error/mismatched_static_lifetime.rs
View File

@ -29,7 +29,13 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
SubregionOrigin::Subtype(box TypeTrace { ref cause, .. }) => cause,
_ => return None,
};
let (parent, impl_def_id) = match &cause.code {
// If we added a "points at argument expression" obligation, we remove it here, we care
// about the original obligation only.
let code = match &cause.code {
ObligationCauseCode::FunctionArgumentObligation { parent_code, .. } => &*parent_code,
_ => &cause.code,
};
let (parent, impl_def_id) = match code {
ObligationCauseCode::MatchImpl(parent, impl_def_id) => (parent, impl_def_id),
_ => return None,
};

6
compiler/rustc_infer/src/traits/mod.rs
View File

@ -66,10 +66,6 @@ pub type Selection<'tcx> = ImplSource<'tcx, PredicateObligation<'tcx>>;
pub struct FulfillmentError<'tcx> {
pub obligation: PredicateObligation<'tcx>,
pub code: FulfillmentErrorCode<'tcx>,
/// Diagnostics only: we opportunistically change the `code.span` when we encounter an
/// obligation error caused by a call argument. When this is the case, we also signal that in
/// this field to ensure accuracy of suggestions.
pub points_at_arg_span: bool,
/// Diagnostics only: the 'root' obligation which resulted in
/// the failure to process `obligation`. This is the obligation
/// that was initially passed to `register_predicate_obligation`
@ -128,7 +124,7 @@ impl<'tcx> FulfillmentError<'tcx> {
code: FulfillmentErrorCode<'tcx>,
root_obligation: PredicateObligation<'tcx>,
) -> FulfillmentError<'tcx> {
FulfillmentError { obligation, code, points_at_arg_span: false, root_obligation }
FulfillmentError { obligation, code, root_obligation }
}
}

18
compiler/rustc_middle/src/traits/mod.rs
View File

@ -253,6 +253,15 @@ pub enum ObligationCauseCode<'tcx> {
DerivedObligation(DerivedObligationCause<'tcx>),
FunctionArgumentObligation {
/// The node of the relevant argument in the function call.
arg_hir_id: hir::HirId,
/// The node of the function call.
call_hir_id: hir::HirId,
/// The obligation introduced by this argument.
parent_code: Lrc<ObligationCauseCode<'tcx>>,
},
/// Error derived when matching traits/impls; see ObligationCause for more details
CompareImplConstObligation,
@ -368,11 +377,12 @@ impl ObligationCauseCode<'_> {
// Return the base obligation, ignoring derived obligations.
pub fn peel_derives(&self) -> &Self {
let mut base_cause = self;
while let BuiltinDerivedObligation(cause)
| ImplDerivedObligation(cause)
| DerivedObligation(cause) = base_cause
while let BuiltinDerivedObligation(DerivedObligationCause { parent_code, .. })
| ImplDerivedObligation(DerivedObligationCause { parent_code, .. })
| DerivedObligation(DerivedObligationCause { parent_code, .. })
| FunctionArgumentObligation { parent_code, .. } = base_cause
{
base_cause = &cause.parent_code;
base_cause = &parent_code;
}
base_cause
}

3
compiler/rustc_trait_selection/src/traits/chalk_fulfill.rs
View File

@ -57,7 +57,6 @@ impl TraitEngine<'tcx> for FulfillmentContext<'tcx> {
.map(|obligation| FulfillmentError {
obligation: obligation.clone(),
code: FulfillmentErrorCode::CodeAmbiguity,
points_at_arg_span: false,
// FIXME - does Chalk have a notation of 'root obligation'?
// This is just for diagnostics, so it's okay if this is wrong
root_obligation: obligation.clone(),
@ -112,7 +111,6 @@ impl TraitEngine<'tcx> for FulfillmentContext<'tcx> {
code: FulfillmentErrorCode::CodeSelectionError(
SelectionError::Unimplemented,
),
points_at_arg_span: false,
// FIXME - does Chalk have a notation of 'root obligation'?
// This is just for diagnostics, so it's okay if this is wrong
root_obligation: obligation,
@ -129,7 +127,6 @@ impl TraitEngine<'tcx> for FulfillmentContext<'tcx> {
code: FulfillmentErrorCode::CodeSelectionError(
SelectionError::Unimplemented,
),
points_at_arg_span: false,
// FIXME - does Chalk have a notation of 'root obligation'?
// This is just for diagnostics, so it's okay if this is wrong
root_obligation: obligation,

15
compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
View File

@ -66,7 +66,6 @@ pub trait InferCtxtExt<'tcx> {
root_obligation: &PredicateObligation<'tcx>,
error: &SelectionError<'tcx>,
fallback_has_occurred: bool,
points_at_arg: bool,
);
/// 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> {
root_obligation: &PredicateObligation<'tcx>,
error: &SelectionError<'tcx>,
fallback_has_occurred: bool,
points_at_arg: bool,
) {
let tcx = self.tcx;
let mut span = obligation.cause.span;
@ -387,7 +385,6 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
&obligation,
&mut err,
&trait_ref,
points_at_arg,
have_alt_message,
) {
self.note_obligation_cause(&mut err, &obligation);
@ -430,8 +427,8 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
err.span_label(enclosing_scope_span, s.as_str());
}
self.suggest_dereferences(&obligation, &mut err, trait_ref, points_at_arg);
self.suggest_fn_call(&obligation, &mut err, trait_ref, points_at_arg);
self.suggest_dereferences(&obligation, &mut err, trait_ref);
self.suggest_fn_call(&obligation, &mut err, trait_ref);
self.suggest_remove_reference(&obligation, &mut err, trait_ref);
self.suggest_semicolon_removal(&obligation, &mut err, span, trait_ref);
self.note_version_mismatch(&mut err, &trait_ref);
@ -500,12 +497,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, '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_ref,
points_at_arg,
);
self.suggest_change_mut(&obligation, &mut err, trait_ref);
}
// 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> {
&error.root_obligation,
selection_error,
fallback_has_occurred,
error.points_at_arg_span,
);
}
FulfillmentErrorCode::CodeProjectionError(ref e) => {

59
compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
View File

@ -54,7 +54,6 @@ pub trait InferCtxtExt<'tcx> {
obligation: &PredicateObligation<'tcx>,
err: &mut DiagnosticBuilder<'tcx>,
trait_ref: ty::PolyTraitRef<'tcx>,
points_at_arg: bool,
);
fn get_closure_name(
@ -69,7 +68,6 @@ pub trait InferCtxtExt<'tcx> {
obligation: &PredicateObligation<'tcx>,
err: &mut DiagnosticBuilder<'_>,
trait_ref: ty::Binder<'tcx, ty::TraitRef<'tcx>>,
points_at_arg: bool,
);
fn suggest_add_reference_to_arg(
@ -77,7 +75,6 @@ pub trait InferCtxtExt<'tcx> {
obligation: &PredicateObligation<'tcx>,
err: &mut DiagnosticBuilder<'_>,
trait_ref: &ty::Binder<'tcx, ty::TraitRef<'tcx>>,
points_at_arg: bool,
has_custom_message: bool,
) -> bool;
@ -93,7 +90,6 @@ pub trait InferCtxtExt<'tcx> {
obligation: &PredicateObligation<'tcx>,
err: &mut DiagnosticBuilder<'_>,
trait_ref: ty::Binder<'tcx, ty::TraitRef<'tcx>>,
points_at_arg: bool,
);
fn suggest_semicolon_removal(
@ -490,16 +486,19 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
obligation: &PredicateObligation<'tcx>,
err: &mut DiagnosticBuilder<'tcx>,
trait_ref: ty::PolyTraitRef<'tcx>,
points_at_arg: bool,
) {
// It only make sense when suggesting dereferences for arguments
if !points_at_arg {
let code = if let ObligationCauseCode::FunctionArgumentObligation { parent_code, .. } =
&obligation.cause.code
{
std::rc::Rc::clone(parent_code)
} else {
return;
}
};
let param_env = obligation.param_env;
let body_id = obligation.cause.body_id;
let span = obligation.cause.span;
let real_trait_ref = match &obligation.cause.code {
let real_trait_ref = match &*code {
ObligationCauseCode::ImplDerivedObligation(cause)
| ObligationCauseCode::DerivedObligation(cause)
| ObligationCauseCode::BuiltinDerivedObligation(cause) => cause.parent_trait_ref,
@ -584,7 +583,6 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
obligation: &PredicateObligation<'tcx>,
err: &mut DiagnosticBuilder<'_>,
trait_ref: ty::Binder<'tcx, ty::TraitRef<'tcx>>,
points_at_arg: bool,
) {
let self_ty = match trait_ref.self_ty().no_bound_vars() {
None => return,
@ -656,11 +654,11 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
}
_ => return,
};
if points_at_arg {
if matches!(obligation.cause.code, ObligationCauseCode::FunctionArgumentObligation { .. }) {
// When the obligation error has been ensured to have been caused by
// an argument, the `obligation.cause.span` points at the expression
// of the argument, so we can provide a suggestion. This is signaled
// by `points_at_arg`. Otherwise, we give a more general note.
// of the argument, so we can provide a suggestion. Otherwise, we give
// a more general note.
err.span_suggestion_verbose(
obligation.cause.span.shrink_to_hi(),
&msg,
@ -677,7 +675,6 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
obligation: &PredicateObligation<'tcx>,
err: &mut DiagnosticBuilder<'_>,
trait_ref: &ty::Binder<'tcx, ty::TraitRef<'tcx>>,
points_at_arg: bool,
has_custom_message: bool,
) -> bool {
let span = obligation.cause.span;
@ -686,9 +683,14 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
ExpnKind::Desugaring(DesugaringKind::ForLoop(ForLoopLoc::IntoIter))
);
if !points_at_arg && !points_at_for_iter {
return false;
}
let code =
if let (ObligationCauseCode::FunctionArgumentObligation { parent_code, .. }, false) =
(&obligation.cause.code, points_at_for_iter)
{
std::rc::Rc::clone(parent_code)
} else {
return false;
};
// List of traits for which it would be nonsensical to suggest borrowing.
// For instance, immutable references are always Copy, so suggesting to
@ -787,7 +789,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
return false;
};
if let ObligationCauseCode::ImplDerivedObligation(obligation) = &obligation.cause.code {
if let ObligationCauseCode::ImplDerivedObligation(obligation) = &*code {
let expected_trait_ref = obligation.parent_trait_ref.skip_binder();
let new_imm_trait_ref =
ty::TraitRef::new(obligation.parent_trait_ref.def_id(), imm_substs);
@ -799,7 +801,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
return try_borrowing(new_mut_trait_ref, expected_trait_ref, true, &[]);
}
} else if let ObligationCauseCode::BindingObligation(_, _)
| ObligationCauseCode::ItemObligation(_) = &obligation.cause.code
| ObligationCauseCode::ItemObligation(_) = &*code
{
if try_borrowing(
ty::TraitRef::new(trait_ref.def_id, imm_substs),
@ -891,8 +893,12 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
obligation: &PredicateObligation<'tcx>,
err: &mut DiagnosticBuilder<'_>,
trait_ref: ty::Binder<'tcx, ty::TraitRef<'tcx>>,
points_at_arg: bool,
) {
let points_at_arg = matches!(
obligation.cause.code,
ObligationCauseCode::FunctionArgumentObligation { .. },
);
let span = obligation.cause.span;
if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span) {
let refs_number =
@ -2289,6 +2295,21 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
)
});
}
ObligationCauseCode::FunctionArgumentObligation {
arg_hir_id: _,
call_hir_id: _,
ref parent_code,
} => {
ensure_sufficient_stack(|| {
self.note_obligation_cause_code(
err,
predicate,
&parent_code,
obligated_types,
seen_requirements,
)
});
}
ObligationCauseCode::CompareImplMethodObligation {
item_name,
trait_item_def_id,

8
compiler/rustc_typeck/src/check/coercion.rs
View File

@ -707,13 +707,7 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
// Object safety violations or miscellaneous.
Err(err) => {
self.report_selection_error(
obligation.clone(),
&obligation,
&err,
false,
false,
);
self.report_selection_error(obligation.clone(), &obligation, &err, false);
// Treat this like an obligation and follow through
// with the unsizing - the lack of a coercion should
// be silent, as it causes a type mismatch later.

19
compiler/rustc_typeck/src/check/fn_ctxt/checks.rs
View File

@ -9,6 +9,7 @@ use crate::check::{
};
use rustc_ast as ast;
use rustc_data_structures::sync::Lrc;
use rustc_errors::{Applicability, DiagnosticBuilder, DiagnosticId};
use rustc_hir as hir;
use rustc_hir::def::{CtorOf, DefKind, Res};
@ -324,6 +325,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
self.point_at_arg_instead_of_call_if_possible(
errors,
&final_arg_types[..],
expr,
sp,
&args,
);
@ -391,7 +393,13 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
) {
for error in errors {
error.obligation.cause.make_mut().span = arg.span;
error.points_at_arg_span = true;
let code = error.obligation.cause.code.clone();
error.obligation.cause.make_mut().code =
ObligationCauseCode::FunctionArgumentObligation {
arg_hir_id: arg.hir_id,
call_hir_id: expr.hir_id,
parent_code: Lrc::new(code),
};
}
}
},
@ -937,6 +945,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
&self,
errors: &mut Vec<traits::FulfillmentError<'tcx>>,
final_arg_types: &[(usize, Ty<'tcx>, Ty<'tcx>)],
expr: &'tcx hir::Expr<'tcx>,
call_sp: Span,
args: &'tcx [hir::Expr<'tcx>],
) {
@ -986,7 +995,13 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
// We make sure that only *one* argument matches the obligation failure
// and we assign the obligation's span to its expression's.
error.obligation.cause.make_mut().span = args[ref_in].span;
error.points_at_arg_span = true;
let code = error.obligation.cause.code.clone();
error.obligation.cause.make_mut().code =
ObligationCauseCode::FunctionArgumentObligation {
arg_hir_id: args[ref_in].hir_id,
call_hir_id: expr.hir_id,
parent_code: Lrc::new(code),
};
}
}
}

4
src/test/ui/traits/negative-impls/negated-auto-traits-error.stderr
View File

@ -43,7 +43,7 @@ error[E0277]: `dummy1c::TestType` cannot be sent between threads safely
LL | is_send((8, TestType));
| ^^^^^^^^^^^^^ `dummy1c::TestType` cannot be sent between threads safely
|
= help: within `({integer}, dummy1c::TestType)`, the trait `Send` is not implemented for `dummy1c::TestType`
= help: the trait `Send` is not implemented for `dummy1c::TestType`
= note: required because it appears within the type `({integer}, dummy1c::TestType)`
note: required by a bound in `is_send`
--> $DIR/negated-auto-traits-error.rs:16:15
@ -75,7 +75,7 @@ error[E0277]: `dummy3::TestType` cannot be sent between threads safely
LL | is_send(Box::new(Outer2(TestType)));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ `dummy3::TestType` cannot be sent between threads safely
|
= help: within `Outer2<dummy3::TestType>`, the trait `Send` is not implemented for `dummy3::TestType`
= help: the trait `Send` is not implemented for `dummy3::TestType`
note: required because it appears within the type `Outer2<dummy3::TestType>`
--> $DIR/negated-auto-traits-error.rs:12:8
|

2
src/test/ui/unsized-locals/unsized-exprs.stderr
View File

@ -14,7 +14,7 @@ error[E0277]: the size for values of type `[u8]` cannot be known at compilation
LL | udrop::<A<[u8]>>(A { 0: *foo() });
| ^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
|
= help: within `A<[u8]>`, the trait `Sized` is not implemented for `[u8]`
= help: the trait `Sized` is not implemented for `[u8]`
note: required because it appears within the type `A<[u8]>`
--> $DIR/unsized-exprs.rs:3:8
|