diff options
4 files changed, 58 insertions, 7 deletions
diff --git a/compiler/rustc_borrowck/src/diagnostics/region_errors.rs b/compiler/rustc_borrowck/src/diagnostics/region_errors.rs index b7e2510e035..df79da76bce 100644 --- a/compiler/rustc_borrowck/src/diagnostics/region_errors.rs +++ b/compiler/rustc_borrowck/src/diagnostics/region_errors.rs @@ -14,7 +14,10 @@ use rustc_infer::infer::{NllRegionVariableOrigin, RelateParamBound}; use rustc_middle::bug; use rustc_middle::hir::place::PlaceBase; use rustc_middle::mir::{AnnotationSource, ConstraintCategory, ReturnConstraint}; -use rustc_middle::ty::{self, GenericArgs, Region, RegionVid, Ty, TyCtxt, TypeVisitor}; +use rustc_middle::ty::fold::fold_regions; +use rustc_middle::ty::{ + self, GenericArgs, Region, RegionVid, Ty, TyCtxt, TypeFoldable, TypeVisitor, +}; use rustc_span::{Ident, Span, kw}; use rustc_trait_selection::error_reporting::InferCtxtErrorExt; use rustc_trait_selection::error_reporting::infer::nice_region_error::{ @@ -183,6 +186,17 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> { } } + /// Map the regions in the type to named regions, where possible. + fn name_regions<T>(&self, tcx: TyCtxt<'tcx>, ty: T) -> T + where + T: TypeFoldable<TyCtxt<'tcx>>, + { + fold_regions(tcx, ty, |region, _| match *region { + ty::ReVar(vid) => self.to_error_region(vid).unwrap_or(region), + _ => region, + }) + } + /// Returns `true` if a closure is inferred to be an `FnMut` closure. fn is_closure_fn_mut(&self, fr: RegionVid) -> bool { if let Some(ty::ReLateParam(late_param)) = self.to_error_region(fr).as_deref() @@ -314,7 +328,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> { let type_test_span = type_test.span; if let Some(lower_bound_region) = lower_bound_region { - let generic_ty = self.regioncx.name_regions( + let generic_ty = self.name_regions( self.infcx.tcx, type_test.generic_kind.to_ty(self.infcx.tcx), ); @@ -323,7 +337,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> { self.body.source.def_id().expect_local(), type_test_span, Some(origin), - self.regioncx.name_regions(self.infcx.tcx, type_test.generic_kind), + self.name_regions(self.infcx.tcx, type_test.generic_kind), lower_bound_region, )); } else { @@ -354,9 +368,13 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> { } RegionErrorKind::UnexpectedHiddenRegion { span, hidden_ty, key, member_region } => { - let named_ty = self.regioncx.name_regions(self.infcx.tcx, hidden_ty); - let named_key = self.regioncx.name_regions(self.infcx.tcx, key); - let named_region = self.regioncx.name_regions(self.infcx.tcx, member_region); + let named_ty = + self.regioncx.name_regions_for_member_constraint(self.infcx.tcx, hidden_ty); + let named_key = + self.regioncx.name_regions_for_member_constraint(self.infcx.tcx, key); + let named_region = self + .regioncx + .name_regions_for_member_constraint(self.infcx.tcx, member_region); let diag = unexpected_hidden_region_diagnostic( self.infcx, self.mir_def_id(), diff --git a/compiler/rustc_borrowck/src/region_infer/opaque_types.rs b/compiler/rustc_borrowck/src/region_infer/opaque_types.rs index 9c19f8b3ad8..54f9e82dbb8 100644 --- a/compiler/rustc_borrowck/src/region_infer/opaque_types.rs +++ b/compiler/rustc_borrowck/src/region_infer/opaque_types.rs @@ -204,7 +204,13 @@ impl<'tcx> RegionInferenceContext<'tcx> { /// that the regions produced are in fact equal to the named region they are /// replaced with. This is fine because this function is only to improve the /// region names in error messages. - pub(crate) fn name_regions<T>(&self, tcx: TyCtxt<'tcx>, ty: T) -> T + /// + /// This differs from `MirBorrowckCtxt::name_regions` since it is particularly + /// lax with mapping region vids that are *shorter* than a universal region to + /// that universal region. This is useful for member region constraints since + /// we want to suggest a universal region name to capture even if it's technically + /// not equal to the error region. + pub(crate) fn name_regions_for_member_constraint<T>(&self, tcx: TyCtxt<'tcx>, ty: T) -> T where T: TypeFoldable<TyCtxt<'tcx>>, { diff --git a/tests/ui/borrowck/alias-liveness/name-region.rs b/tests/ui/borrowck/alias-liveness/name-region.rs new file mode 100644 index 00000000000..9545a9eed2f --- /dev/null +++ b/tests/ui/borrowck/alias-liveness/name-region.rs @@ -0,0 +1,13 @@ +// Make sure we don't ICE when trying to name the regions that appear in the alias +// of the type test error. + +trait AnotherTrait { + type Ty2<'a>; +} + +fn test_alias<T: AnotherTrait>(_: &'static T::Ty2<'_>) { + let _: &'static T::Ty2<'_>; + //~^ ERROR the associated type `<T as AnotherTrait>::Ty2<'_>` may not live long enough +} + +fn main() {} diff --git a/tests/ui/borrowck/alias-liveness/name-region.stderr b/tests/ui/borrowck/alias-liveness/name-region.stderr new file mode 100644 index 00000000000..9a5dd711c68 --- /dev/null +++ b/tests/ui/borrowck/alias-liveness/name-region.stderr @@ -0,0 +1,14 @@ +error[E0310]: the associated type `<T as AnotherTrait>::Ty2<'_>` may not live long enough + --> $DIR/name-region.rs:9:12 + | +LL | let _: &'static T::Ty2<'_>; + | ^^^^^^^^^^^^^^^^^^^ + | | + | the associated type `<T as AnotherTrait>::Ty2<'_>` must be valid for the static lifetime... + | ...so that the type `<T as AnotherTrait>::Ty2<'_>` will meet its required lifetime bounds + | + = help: consider adding an explicit lifetime bound `<T as AnotherTrait>::Ty2<'_>: 'static`... + +error: aborting due to 1 previous error + +For more information about this error, try `rustc --explain E0310`. |