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Report "nice" placeholder errors more often

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If we have a cause containing `ValuePairs::PolyTraitRefs` but neither
TraitRef has any escaping bound regions then we report the same error as
for `ValuePairs::TraitRefs`.
This commit is contained in:
Matthew Jasper 2021-02-09 22:59:32 +00:00
parent daab6db1a0
commit 94c11dfe78
19 changed files with 181 additions and 263 deletions
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142
compiler/rustc_infer/src/infer/error_reporting/nice_region_error/placeholder_error.rs
View file

@ -30,157 +30,153 @@ impl NiceRegionError<'me, 'tcx> {
Some(RegionResolutionError::SubSupConflict(
vid,
_,
SubregionOrigin::Subtype(box TypeTrace {
cause,
values: ValuePairs::TraitRefs(ExpectedFound { expected, found }),
}),
SubregionOrigin::Subtype(box TypeTrace { cause, values }),
sub_placeholder @ ty::RePlaceholder(_),
_,
sup_placeholder @ ty::RePlaceholder(_),
)) if expected.def_id == found.def_id => Some(self.try_report_placeholders_trait(
)) => self.try_report_trait_placeholder_mismatch(
Some(self.tcx().mk_region(ty::ReVar(*vid))),
cause,
Some(sub_placeholder),
Some(sup_placeholder),
expected.def_id,
expected.substs,
found.substs,
)),
values,
),
Some(RegionResolutionError::SubSupConflict(
vid,
_,
SubregionOrigin::Subtype(box TypeTrace {
cause,
values: ValuePairs::TraitRefs(ExpectedFound { expected, found }),
}),
SubregionOrigin::Subtype(box TypeTrace { cause, values }),
sub_placeholder @ ty::RePlaceholder(_),
_,
_,
)) if expected.def_id == found.def_id => Some(self.try_report_placeholders_trait(
)) => self.try_report_trait_placeholder_mismatch(
Some(self.tcx().mk_region(ty::ReVar(*vid))),
cause,
Some(sub_placeholder),
None,
expected.def_id,
expected.substs,
found.substs,
)),
values,
),
Some(RegionResolutionError::SubSupConflict(
vid,
_,
SubregionOrigin::Subtype(box TypeTrace {
cause,
values: ValuePairs::TraitRefs(ExpectedFound { expected, found }),
}),
SubregionOrigin::Subtype(box TypeTrace { cause, values }),
_,
_,
sup_placeholder @ ty::RePlaceholder(_),
)) if expected.def_id == found.def_id => Some(self.try_report_placeholders_trait(
)) => self.try_report_trait_placeholder_mismatch(
Some(self.tcx().mk_region(ty::ReVar(*vid))),
cause,
None,
Some(*sup_placeholder),
expected.def_id,
expected.substs,
found.substs,
)),
values,
),
Some(RegionResolutionError::SubSupConflict(
vid,
_,
_,
_,
SubregionOrigin::Subtype(box TypeTrace {
cause,
values: ValuePairs::TraitRefs(ExpectedFound { expected, found }),
}),
SubregionOrigin::Subtype(box TypeTrace { cause, values }),
sup_placeholder @ ty::RePlaceholder(_),
)) if expected.def_id == found.def_id => Some(self.try_report_placeholders_trait(
)) => self.try_report_trait_placeholder_mismatch(
Some(self.tcx().mk_region(ty::ReVar(*vid))),
cause,
None,
Some(*sup_placeholder),
expected.def_id,
expected.substs,
found.substs,
)),
values,
),
Some(RegionResolutionError::UpperBoundUniverseConflict(
vid,
_,
_,
SubregionOrigin::Subtype(box TypeTrace {
cause,
values: ValuePairs::TraitRefs(ExpectedFound { expected, found }),
}),
SubregionOrigin::Subtype(box TypeTrace { cause, values }),
sup_placeholder @ ty::RePlaceholder(_),
)) if expected.def_id == found.def_id => Some(self.try_report_placeholders_trait(
)) => self.try_report_trait_placeholder_mismatch(
Some(self.tcx().mk_region(ty::ReVar(*vid))),
cause,
None,
Some(*sup_placeholder),
expected.def_id,
expected.substs,
found.substs,
)),
values,
),
Some(RegionResolutionError::ConcreteFailure(
SubregionOrigin::Subtype(box TypeTrace {
cause,
values: ValuePairs::TraitRefs(ExpectedFound { expected, found }),
}),
SubregionOrigin::Subtype(box TypeTrace { cause, values }),
sub_region @ ty::RePlaceholder(_),
sup_region @ ty::RePlaceholder(_),
)) if expected.def_id == found.def_id => Some(self.try_report_placeholders_trait(
)) => self.try_report_trait_placeholder_mismatch(
None,
cause,
Some(*sub_region),
Some(*sup_region),
expected.def_id,
expected.substs,
found.substs,
)),
values,
),
Some(RegionResolutionError::ConcreteFailure(
SubregionOrigin::Subtype(box TypeTrace {
cause,
values: ValuePairs::TraitRefs(ExpectedFound { expected, found }),
}),
SubregionOrigin::Subtype(box TypeTrace { cause, values }),
sub_region @ ty::RePlaceholder(_),
sup_region,
)) if expected.def_id == found.def_id => Some(self.try_report_placeholders_trait(
)) => self.try_report_trait_placeholder_mismatch(
Some(sup_region),
cause,
Some(*sub_region),
None,
expected.def_id,
expected.substs,
found.substs,
)),
values,
),
Some(RegionResolutionError::ConcreteFailure(
SubregionOrigin::Subtype(box TypeTrace {
cause,
values: ValuePairs::TraitRefs(ExpectedFound { expected, found }),
}),
SubregionOrigin::Subtype(box TypeTrace { cause, values }),
sub_region,
sup_region @ ty::RePlaceholder(_),
)) if expected.def_id == found.def_id => Some(self.try_report_placeholders_trait(
)) => self.try_report_trait_placeholder_mismatch(
Some(sub_region),
cause,
None,
Some(*sup_region),
expected.def_id,
expected.substs,
found.substs,
)),
values,
),
_ => None,
}
}
fn try_report_trait_placeholder_mismatch(
&self,
vid: Option<ty::Region<'tcx>>,
cause: &ObligationCause<'tcx>,
sub_placeholder: Option<ty::Region<'tcx>>,
sup_placeholder: Option<ty::Region<'tcx>>,
value_pairs: &ValuePairs<'tcx>,
) -> Option<DiagnosticBuilder<'tcx>> {
let (expected_substs, found_substs, trait_def_id) = match value_pairs {
ValuePairs::TraitRefs(ExpectedFound { expected, found })
if expected.def_id == found.def_id =>
{
(expected.substs, found.substs, expected.def_id)
}
ValuePairs::PolyTraitRefs(ExpectedFound { expected, found })
if expected.def_id() == found.def_id() =>
{
// It's possible that the placeholders come from a binder
// outside of this value pair. Use `no_bound_vars` as a
// simple heuristic for that.
(expected.no_bound_vars()?.substs, found.no_bound_vars()?.substs, expected.def_id())
}
_ => return None,
};
Some(self.report_trait_placeholder_mismatch(
vid,
cause,
sub_placeholder,
sup_placeholder,
trait_def_id,
expected_substs,
found_substs,
))
}
// error[E0308]: implementation of `Foo` does not apply to enough lifetimes
// --> /home/nmatsakis/tmp/foo.rs:12:5
// |
@ -191,7 +187,7 @@ impl NiceRegionError<'me, 'tcx> {
// = note: `T` must implement `...` for any two lifetimes `'1` and `'2`.
// = note: However, the type `T` only implements `...` for some specific lifetime `'2`.
#[instrument(level = "debug", skip(self))]
fn try_report_placeholders_trait(
fn report_trait_placeholder_mismatch(
&self,
vid: Option<ty::Region<'tcx>>,
cause: &ObligationCause<'tcx>,