From 820e2680ec2f7f5f1b42dc94374986d251a22aff Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?R=C3=A9my=20Rakic?= Date: Mon, 23 Aug 2021 23:31:01 +0200 Subject: [PATCH 1/2] handle ascription type op in NLL HRTB diagnostics Refactors the `type_op_ascribe_user_type` query into a version which accepts a span, and uses it in the nicer NLL HRTB bound region errors. --- .../diagnostics/bound_region_errors.rs | 42 ++++++++++++++-- compiler/rustc_traits/src/lib.rs | 2 +- compiler/rustc_traits/src/type_op.rs | 48 +++++++++++++------ 3 files changed, 72 insertions(+), 20 deletions(-) diff --git a/compiler/rustc_mir/src/borrow_check/diagnostics/bound_region_errors.rs b/compiler/rustc_mir/src/borrow_check/diagnostics/bound_region_errors.rs index d0284dd030236..ac30093ba8260 100644 --- a/compiler/rustc_mir/src/borrow_check/diagnostics/bound_region_errors.rs +++ b/compiler/rustc_mir/src/borrow_check/diagnostics/bound_region_errors.rs @@ -9,7 +9,7 @@ use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable}; use rustc_span::Span; use rustc_trait_selection::traits::query::type_op; use rustc_trait_selection::traits::{SelectionContext, TraitEngineExt as _}; -use rustc_traits::type_op_prove_predicate_with_span; +use rustc_traits::{type_op_ascribe_user_type_with_span, type_op_prove_predicate_with_span}; use std::fmt; use std::rc::Rc; @@ -104,10 +104,11 @@ impl<'tcx, T: Copy + fmt::Display + TypeFoldable<'tcx> + 'tcx> ToUniverseInfo<'t impl<'tcx> ToUniverseInfo<'tcx> for Canonical<'tcx, ty::ParamEnvAnd<'tcx, type_op::AscribeUserType<'tcx>>> { - fn to_universe_info(self, _base_universe: ty::UniverseIndex) -> UniverseInfo<'tcx> { - // Ascribe user type isn't usually called on types that have different - // bound regions. - UniverseInfo::other() + fn to_universe_info(self, base_universe: ty::UniverseIndex) -> UniverseInfo<'tcx> { + UniverseInfo(UniverseInfoInner::TypeOp(Rc::new(AscribeUserTypeQuery { + canonical_query: self, + base_universe, + }))) } } @@ -267,6 +268,37 @@ where } } +struct AscribeUserTypeQuery<'tcx> { + canonical_query: Canonical<'tcx, ty::ParamEnvAnd<'tcx, type_op::AscribeUserType<'tcx>>>, + base_universe: ty::UniverseIndex, +} + +impl TypeOpInfo<'tcx> for AscribeUserTypeQuery<'tcx> { + fn fallback_error(&self, tcx: TyCtxt<'tcx>, span: Span) -> DiagnosticBuilder<'tcx> { + // FIXME: This error message isn't great, but it doesn't show up in the existing UI tests, + // and is only the fallback when the nice error fails. Consider improving this some more. + tcx.sess.struct_span_err(span, "higher-ranked lifetime error") + } + + fn base_universe(&self) -> ty::UniverseIndex { + self.base_universe + } + + fn nice_error( + &self, + tcx: TyCtxt<'tcx>, + span: Span, + placeholder_region: ty::Region<'tcx>, + error_region: Option>, + ) -> Option> { + tcx.infer_ctxt().enter_with_canonical(span, &self.canonical_query, |ref infcx, key, _| { + let mut fulfill_cx = >::new(tcx); + type_op_ascribe_user_type_with_span(infcx, &mut *fulfill_cx, key, Some(span)).ok()?; + try_extract_error_from_fulfill_cx(fulfill_cx, infcx, placeholder_region, error_region) + }) + } +} + fn try_extract_error_from_fulfill_cx<'tcx>( mut fulfill_cx: Box + 'tcx>, infcx: &InferCtxt<'_, 'tcx>, diff --git a/compiler/rustc_traits/src/lib.rs b/compiler/rustc_traits/src/lib.rs index 8dd7c5bdfaebc..48c46c3069328 100644 --- a/compiler/rustc_traits/src/lib.rs +++ b/compiler/rustc_traits/src/lib.rs @@ -19,7 +19,7 @@ mod normalize_erasing_regions; mod normalize_projection_ty; mod type_op; -pub use type_op::type_op_prove_predicate_with_span; +pub use type_op::{type_op_ascribe_user_type_with_span, type_op_prove_predicate_with_span}; use rustc_middle::ty::query::Providers; diff --git a/compiler/rustc_traits/src/type_op.rs b/compiler/rustc_traits/src/type_op.rs index c2e0a9987858e..a76fb84261615 100644 --- a/compiler/rustc_traits/src/type_op.rs +++ b/compiler/rustc_traits/src/type_op.rs @@ -40,18 +40,28 @@ fn type_op_ascribe_user_type<'tcx>( canonicalized: Canonical<'tcx, ParamEnvAnd<'tcx, AscribeUserType<'tcx>>>, ) -> Result<&'tcx Canonical<'tcx, QueryResponse<'tcx, ()>>, NoSolution> { tcx.infer_ctxt().enter_canonical_trait_query(&canonicalized, |infcx, fulfill_cx, key| { - let (param_env, AscribeUserType { mir_ty, def_id, user_substs }) = key.into_parts(); - - debug!( - "type_op_ascribe_user_type: mir_ty={:?} def_id={:?} user_substs={:?}", - mir_ty, def_id, user_substs - ); + type_op_ascribe_user_type_with_span(infcx, fulfill_cx, key, None) + }) +} - let mut cx = AscribeUserTypeCx { infcx, param_env, fulfill_cx }; - cx.relate_mir_and_user_ty(mir_ty, def_id, user_substs)?; +/// The core of the `type_op_ascribe_user_type` query: for diagnostics purposes in NLL HRTB errors, +/// this query can be re-run to better track the span of the obligation cause, and improve the error +/// message. Do not call directly unless you're in that very specific context. +pub fn type_op_ascribe_user_type_with_span<'a, 'tcx: 'a>( + infcx: &'a InferCtxt<'a, 'tcx>, + fulfill_cx: &'a mut dyn TraitEngine<'tcx>, + key: ParamEnvAnd<'tcx, AscribeUserType<'tcx>>, + span: Option, +) -> Result<(), NoSolution> { + let (param_env, AscribeUserType { mir_ty, def_id, user_substs }) = key.into_parts(); + debug!( + "type_op_ascribe_user_type: mir_ty={:?} def_id={:?} user_substs={:?}", + mir_ty, def_id, user_substs + ); - Ok(()) - }) + let mut cx = AscribeUserTypeCx { infcx, param_env, fulfill_cx }; + cx.relate_mir_and_user_ty(mir_ty, def_id, user_substs, span)?; + Ok(()) } struct AscribeUserTypeCx<'me, 'tcx> { @@ -85,10 +95,15 @@ impl AscribeUserTypeCx<'me, 'tcx> { Ok(()) } - fn prove_predicate(&mut self, predicate: Predicate<'tcx>) { + fn prove_predicate(&mut self, predicate: Predicate<'tcx>, span: Option) { + let cause = if let Some(span) = span { + ObligationCause::dummy_with_span(span) + } else { + ObligationCause::dummy() + }; self.fulfill_cx.register_predicate_obligation( self.infcx, - Obligation::new(ObligationCause::dummy(), self.param_env, predicate), + Obligation::new(cause, self.param_env, predicate), ); } @@ -108,6 +123,7 @@ impl AscribeUserTypeCx<'me, 'tcx> { mir_ty: Ty<'tcx>, def_id: DefId, user_substs: UserSubsts<'tcx>, + span: Option, ) -> Result<(), NoSolution> { let UserSubsts { user_self_ty, substs } = user_substs; let tcx = self.tcx(); @@ -129,7 +145,7 @@ impl AscribeUserTypeCx<'me, 'tcx> { debug!(?instantiated_predicates.predicates); for instantiated_predicate in instantiated_predicates.predicates { let instantiated_predicate = self.normalize(instantiated_predicate); - self.prove_predicate(instantiated_predicate); + self.prove_predicate(instantiated_predicate, span); } if let Some(UserSelfTy { impl_def_id, self_ty }) = user_self_ty { @@ -141,6 +157,7 @@ impl AscribeUserTypeCx<'me, 'tcx> { self.prove_predicate( ty::PredicateKind::WellFormed(impl_self_ty.into()).to_predicate(self.tcx()), + span, ); } @@ -155,7 +172,10 @@ impl AscribeUserTypeCx<'me, 'tcx> { // them? This would only be relevant if some input // type were ill-formed but did not appear in `ty`, // which...could happen with normalization... - self.prove_predicate(ty::PredicateKind::WellFormed(ty.into()).to_predicate(self.tcx())); + self.prove_predicate( + ty::PredicateKind::WellFormed(ty.into()).to_predicate(self.tcx()), + span, + ); Ok(()) } } From 7b0e564e7cd3bebea7c41165db42a7b15010d2cc Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?R=C3=A9my=20Rakic?= Date: Mon, 23 Aug 2021 23:34:04 +0200 Subject: [PATCH 2/2] Update NLL HRTB type ascription blessed expectations Some of these tests have reached parity with the migrate-mode output. --- src/test/ui/hrtb/due-to-where-clause.nll.stderr | 8 -------- src/test/ui/hrtb/hrtb-cache-issue-54302.nll.stderr | 8 -------- src/test/ui/hrtb/hrtb-just-for-static.nll.stderr | 7 +++++-- src/test/ui/issues/issue-54302.nll.stderr | 8 -------- 4 files changed, 5 insertions(+), 26 deletions(-) delete mode 100644 src/test/ui/hrtb/due-to-where-clause.nll.stderr delete mode 100644 src/test/ui/hrtb/hrtb-cache-issue-54302.nll.stderr delete mode 100644 src/test/ui/issues/issue-54302.nll.stderr diff --git a/src/test/ui/hrtb/due-to-where-clause.nll.stderr b/src/test/ui/hrtb/due-to-where-clause.nll.stderr deleted file mode 100644 index 90803a0adb01b..0000000000000 --- a/src/test/ui/hrtb/due-to-where-clause.nll.stderr +++ /dev/null @@ -1,8 +0,0 @@ -error: higher-ranked subtype error - --> $DIR/due-to-where-clause.rs:2:5 - | -LL | test::(&mut 42); - | ^^^^^^^^^^^^ - -error: aborting due to previous error - diff --git a/src/test/ui/hrtb/hrtb-cache-issue-54302.nll.stderr b/src/test/ui/hrtb/hrtb-cache-issue-54302.nll.stderr deleted file mode 100644 index 4de35d70c30a3..0000000000000 --- a/src/test/ui/hrtb/hrtb-cache-issue-54302.nll.stderr +++ /dev/null @@ -1,8 +0,0 @@ -error: higher-ranked subtype error - --> $DIR/hrtb-cache-issue-54302.rs:19:5 - | -LL | assert_deserialize_owned::<&'static str>(); - | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ - -error: aborting due to previous error - diff --git a/src/test/ui/hrtb/hrtb-just-for-static.nll.stderr b/src/test/ui/hrtb/hrtb-just-for-static.nll.stderr index a812282def9a8..17d59bb321a45 100644 --- a/src/test/ui/hrtb/hrtb-just-for-static.nll.stderr +++ b/src/test/ui/hrtb/hrtb-just-for-static.nll.stderr @@ -17,11 +17,14 @@ LL | want_hrtb::<&'a u32>() | = help: consider replacing `'a` with `'static` -error: higher-ranked subtype error +error: implementation of `Foo` is not general enough --> $DIR/hrtb-just-for-static.rs:30:5 | LL | want_hrtb::<&'a u32>() - | ^^^^^^^^^^^^^^^^^^^^ + | ^^^^^^^^^^^^^^^^^^^^ implementation of `Foo` is not general enough + | + = note: `Foo<&'0 isize>` would have to be implemented for the type `&u32`, for any lifetime `'0`... + = note: ...but `Foo<&'1 isize>` is actually implemented for the type `&'1 u32`, for some specific lifetime `'1` error: aborting due to 3 previous errors diff --git a/src/test/ui/issues/issue-54302.nll.stderr b/src/test/ui/issues/issue-54302.nll.stderr deleted file mode 100644 index e68de0312824d..0000000000000 --- a/src/test/ui/issues/issue-54302.nll.stderr +++ /dev/null @@ -1,8 +0,0 @@ -error: higher-ranked subtype error - --> $DIR/issue-54302.rs:13:5 - | -LL | assert_deserialize_owned::<&'static str>(); - | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ - -error: aborting due to previous error -