diff options
| -rw-r--r-- | compiler/rustc_hir/src/hir.rs | 2 | ||||
| -rw-r--r-- | compiler/rustc_resolve/src/late/lifetimes.rs | 71 | ||||
| -rw-r--r-- | src/test/ui/impl-trait/universal_wrong_hrtb.rs | 8 | ||||
| -rw-r--r-- | src/test/ui/impl-trait/universal_wrong_hrtb.stderr | 14 |
4 files changed, 87 insertions, 8 deletions
diff --git a/compiler/rustc_hir/src/hir.rs b/compiler/rustc_hir/src/hir.rs index cb2e66090e7..83821b5b536 100644 --- a/compiler/rustc_hir/src/hir.rs +++ b/compiler/rustc_hir/src/hir.rs @@ -734,7 +734,7 @@ impl<'hir> WherePredicate<'hir> { } } -#[derive(Debug, HashStable_Generic, PartialEq, Eq)] +#[derive(Copy, Clone, Debug, HashStable_Generic, PartialEq, Eq)] pub enum PredicateOrigin { WhereClause, GenericParam, diff --git a/compiler/rustc_resolve/src/late/lifetimes.rs b/compiler/rustc_resolve/src/late/lifetimes.rs index 11f80b314d7..bfc42902be4 100644 --- a/compiler/rustc_resolve/src/late/lifetimes.rs +++ b/compiler/rustc_resolve/src/late/lifetimes.rs @@ -207,6 +207,13 @@ enum Scope<'a> { /// In some cases not allowing late bounds allows us to avoid ICEs. /// This is almost ways set to true. allow_late_bound: bool, + + /// If this binder comes from a where clause, specify how it was created. + /// This is used to diagnose inaccessible lifetimes in APIT: + /// ```ignore (illustrative) + /// fn foo(x: impl for<'a> Trait<'a, Assoc = impl Copy + 'a>) {} + /// ``` + where_bound_origin: Option<hir::PredicateOrigin>, }, /// Lifetimes introduced by a fn are scoped to the call-site for that fn, @@ -277,8 +284,9 @@ impl<'a> fmt::Debug for TruncatedScopeDebug<'a> { opaque_type_parent, scope_type, hir_id, - s: _, allow_late_bound, + where_bound_origin, + s: _, } => f .debug_struct("Binder") .field("lifetimes", lifetimes) @@ -286,8 +294,9 @@ impl<'a> fmt::Debug for TruncatedScopeDebug<'a> { .field("opaque_type_parent", opaque_type_parent) .field("scope_type", scope_type) .field("hir_id", hir_id) - .field("s", &"..") .field("allow_late_bound", allow_late_bound) + .field("where_bound_origin", where_bound_origin) + .field("s", &"..") .finish(), Scope::Body { id, s: _ } => { f.debug_struct("Body").field("id", id).field("s", &"..").finish() @@ -638,6 +647,7 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> { opaque_type_parent: false, scope_type: BinderScopeType::Normal, allow_late_bound: true, + where_bound_origin: None, }; self.with(scope, move |this| intravisit::walk_fn(this, fk, fd, b, s, hir_id)); } @@ -753,6 +763,7 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> { scope_type: BinderScopeType::Normal, s: ROOT_SCOPE, allow_late_bound: false, + where_bound_origin: None, }; self.with(scope, |this| { let scope = Scope::TraitRefBoundary { s: this.scope }; @@ -818,6 +829,7 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> { opaque_type_parent: false, scope_type: BinderScopeType::Normal, allow_late_bound: true, + where_bound_origin: None, }; self.with(scope, |this| { // a bare fn has no bounds, so everything @@ -1006,6 +1018,7 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> { opaque_type_parent: false, scope_type: BinderScopeType::Normal, allow_late_bound: false, + where_bound_origin: None, }; this.with(scope, |this| { this.visit_generics(generics); @@ -1026,6 +1039,7 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> { opaque_type_parent: false, scope_type: BinderScopeType::Normal, allow_late_bound: false, + where_bound_origin: None, }; self.with(scope, |this| { let scope = Scope::TraitRefBoundary { s: this.scope }; @@ -1084,6 +1098,7 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> { opaque_type_parent: true, scope_type: BinderScopeType::Normal, allow_late_bound: false, + where_bound_origin: None, }; self.with(scope, |this| { let scope = Scope::TraitRefBoundary { s: this.scope }; @@ -1151,6 +1166,7 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> { opaque_type_parent: true, scope_type: BinderScopeType::Normal, allow_late_bound: true, + where_bound_origin: None, }; self.with(scope, |this| { let scope = Scope::TraitRefBoundary { s: this.scope }; @@ -1266,6 +1282,7 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> { ref bounded_ty, bounds, ref bound_generic_params, + origin, .. }) => { let (lifetimes, binders): (FxIndexMap<LocalDefId, Region>, Vec<_>) = @@ -1296,6 +1313,7 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> { opaque_type_parent: false, scope_type: BinderScopeType::Normal, allow_late_bound: true, + where_bound_origin: Some(origin), }; this.with(scope, |this| { this.visit_ty(&bounded_ty); @@ -1368,6 +1386,7 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> { opaque_type_parent: false, scope_type, allow_late_bound: true, + where_bound_origin: None, }; self.with(scope, |this| { intravisit::walk_param_bound(this, bound); @@ -1420,6 +1439,7 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> { opaque_type_parent: false, scope_type, allow_late_bound: true, + where_bound_origin: None, }; self.with(scope, |this| { walk_list!(this, visit_generic_param, trait_ref.bound_generic_params); @@ -1680,6 +1700,7 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> { opaque_type_parent: true, scope_type: BinderScopeType::Normal, allow_late_bound: true, + where_bound_origin: None, }; self.with(scope, walk); } @@ -1783,12 +1804,48 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> { } self.insert_lifetime(lifetime_ref, def); - } else { - self.tcx.sess.delay_span_bug( - lifetime_ref.span, - &format!("Could not resolve {:?} in scope {:#?}", lifetime_ref, self.scope,), - ); + return; } + + // We may fail to resolve higher-ranked lifetimes that are mentionned by APIT. + // AST-based resolution does not care for impl-trait desugaring, which are the + // responibility of lowering. This may create a mismatch between the resolution + // AST found (`region_def_id`) which points to HRTB, and what HIR allows. + // ``` + // fn foo(x: impl for<'a> Trait<'a, Assoc = impl Copy + 'a>) {} + // ``` + // + // In such case, walk back the binders to diagnose it properly. + let mut scope = self.scope; + loop { + match *scope { + Scope::Binder { + where_bound_origin: Some(hir::PredicateOrigin::ImplTrait), .. + } => { + let mut err = self.tcx.sess.struct_span_err( + lifetime_ref.span, + "`impl Trait` can only mention lifetimes bound at the fn or impl level", + ); + err.span_note(self.tcx.def_span(region_def_id), "lifetime declared here"); + err.emit(); + return; + } + Scope::Root => break, + Scope::Binder { s, .. } + | Scope::Body { s, .. } + | Scope::Elision { s, .. } + | Scope::ObjectLifetimeDefault { s, .. } + | Scope::Supertrait { s, .. } + | Scope::TraitRefBoundary { s, .. } => { + scope = s; + } + } + } + + self.tcx.sess.delay_span_bug( + lifetime_ref.span, + &format!("Could not resolve {:?} in scope {:#?}", lifetime_ref, self.scope,), + ); } fn visit_segment_args( diff --git a/src/test/ui/impl-trait/universal_wrong_hrtb.rs b/src/test/ui/impl-trait/universal_wrong_hrtb.rs new file mode 100644 index 00000000000..b9551c2ceb0 --- /dev/null +++ b/src/test/ui/impl-trait/universal_wrong_hrtb.rs @@ -0,0 +1,8 @@ +trait Trait<'a> { + type Assoc; +} + +fn test_argument_position(x: impl for<'a> Trait<'a, Assoc = impl Copy + 'a>) {} +//~^ ERROR `impl Trait` can only mention lifetimes bound at the fn or impl level + +fn main() {} diff --git a/src/test/ui/impl-trait/universal_wrong_hrtb.stderr b/src/test/ui/impl-trait/universal_wrong_hrtb.stderr new file mode 100644 index 00000000000..37eb8dfa1a1 --- /dev/null +++ b/src/test/ui/impl-trait/universal_wrong_hrtb.stderr @@ -0,0 +1,14 @@ +error: `impl Trait` can only mention lifetimes bound at the fn or impl level + --> $DIR/universal_wrong_hrtb.rs:5:73 + | +LL | fn test_argument_position(x: impl for<'a> Trait<'a, Assoc = impl Copy + 'a>) {} + | ^^ + | +note: lifetime declared here + --> $DIR/universal_wrong_hrtb.rs:5:39 + | +LL | fn test_argument_position(x: impl for<'a> Trait<'a, Assoc = impl Copy + 'a>) {} + | ^^ + +error: aborting due to previous error + |