Rollup merge of #119868 - oli-obk:unknown_lifetime_ice, r=compiler-errors

Register even erroneous impls

Otherwise the specialization graph fails to pick it up, even though other code assumes that all impl blocks have an entry in the specialization graph.

also includes an unrelated cleanup of the specialization graph query

fixes  #119827

9 files changed, 187 insertions, 51 deletions

diff --git a/compiler/rustc_middle/src/arena.rs b/compiler/rustc_middle/src/arena.rs
index 0ab09dadf58..8a4fd01437f 100644
--- a/compiler/rustc_middle/src/arena.rs
+++ b/compiler/rustc_middle/src/arena.rs
@@ -113,6 +113,7 @@ macro_rules! arena_types {
             [] stripped_cfg_items: rustc_ast::expand::StrippedCfgItem,
             [] mod_child: rustc_middle::metadata::ModChild,
             [] features: rustc_feature::Features,
+            [decode] specialization_graph: rustc_middle::traits::specialization_graph::Graph,
         ]);
     )
 }
diff --git a/compiler/rustc_middle/src/query/mod.rs b/compiler/rustc_middle/src/query/mod.rs
index 0e3b9984423..1dc77220881 100644
--- a/compiler/rustc_middle/src/query/mod.rs
+++ b/compiler/rustc_middle/src/query/mod.rs
@@ -1294,8 +1294,7 @@ rustc_queries! {
         desc { |tcx| "finding trait impls of `{}`", tcx.def_path_str(trait_id) }
     }
 
-    query specialization_graph_of(trait_id: DefId) -> &'tcx specialization_graph::Graph {
-        arena_cache
+    query specialization_graph_of(trait_id: DefId) -> Result<&'tcx specialization_graph::Graph, ErrorGuaranteed> {
         desc { |tcx| "building specialization graph of trait `{}`", tcx.def_path_str(trait_id) }
         cache_on_disk_if { true }
     }
diff --git a/compiler/rustc_middle/src/query/on_disk_cache.rs b/compiler/rustc_middle/src/query/on_disk_cache.rs
index 31db4ba62fb..f4dfbe059eb 100644
--- a/compiler/rustc_middle/src/query/on_disk_cache.rs
+++ b/compiler/rustc_middle/src/query/on_disk_cache.rs
@@ -786,6 +786,15 @@ impl<'a, 'tcx> Decodable<CacheDecoder<'a, 'tcx>> for &'tcx [rustc_ast::InlineAsm
     }
 }
 
+impl<'a, 'tcx> Decodable<CacheDecoder<'a, 'tcx>>
+    for &'tcx crate::traits::specialization_graph::Graph
+{
+    #[inline]
+    fn decode(d: &mut CacheDecoder<'a, 'tcx>) -> Self {
+        RefDecodable::decode(d)
+    }
+}
+
 macro_rules! impl_ref_decoder {
     (<$tcx:tt> $($ty:ty,)*) => {
         $(impl<'a, $tcx> Decodable<CacheDecoder<'a, $tcx>> for &$tcx [$ty] {
diff --git a/compiler/rustc_middle/src/traits/specialization_graph.rs b/compiler/rustc_middle/src/traits/specialization_graph.rs
index 898258445dc..ba29d4040a1 100644
--- a/compiler/rustc_middle/src/traits/specialization_graph.rs
+++ b/compiler/rustc_middle/src/traits/specialization_graph.rs
@@ -30,18 +30,16 @@ pub struct Graph {
 
     /// The "root" impls are found by looking up the trait's def_id.
     pub children: DefIdMap<Children>,
-
-    /// Whether an error was emitted while constructing the graph.
-    pub has_errored: Option<ErrorGuaranteed>,
 }
 
 impl Graph {
     pub fn new() -> Graph {
-        Graph { parent: Default::default(), children: Default::default(), has_errored: None }
+        Graph { parent: Default::default(), children: Default::default() }
     }
 
     /// The parent of a given impl, which is the `DefId` of the trait when the
     /// impl is a "specialization root".
+    #[track_caller]
     pub fn parent(&self, child: DefId) -> DefId {
         *self.parent.get(&child).unwrap_or_else(|| panic!("Failed to get parent for {child:?}"))
     }
@@ -255,13 +253,9 @@ pub fn ancestors(
     trait_def_id: DefId,
     start_from_impl: DefId,
 ) -> Result<Ancestors<'_>, ErrorGuaranteed> {
-    let specialization_graph = tcx.specialization_graph_of(trait_def_id);
+    let specialization_graph = tcx.specialization_graph_of(trait_def_id)?;
 
-    if let Some(reported) = specialization_graph.has_errored {
-        Err(reported)
-    } else if let Err(reported) =
-        tcx.type_of(start_from_impl).instantiate_identity().error_reported()
-    {
+    if let Err(reported) = tcx.type_of(start_from_impl).instantiate_identity().error_reported() {
         Err(reported)
     } else {
         Ok(Ancestors {
diff --git a/compiler/rustc_middle/src/ty/fast_reject.rs b/compiler/rustc_middle/src/ty/fast_reject.rs
index 6ed68f90eb3..b71919adc58 100644
--- a/compiler/rustc_middle/src/ty/fast_reject.rs
+++ b/compiler/rustc_middle/src/ty/fast_reject.rs
@@ -32,6 +32,7 @@ pub enum SimplifiedType {
     CoroutineWitness(DefId),
     Function(usize),
     Placeholder,
+    Error,
 }
 
 /// Generic parameters are pretty much just bound variables, e.g.
@@ -153,7 +154,8 @@ pub fn simplify_type<'tcx>(
             TreatParams::ForLookup | TreatParams::AsCandidateKey => None,
         },
         ty::Foreign(def_id) => Some(SimplifiedType::Foreign(def_id)),
-        ty::Bound(..) | ty::Infer(_) | ty::Error(_) => None,
+        ty::Error(_) => Some(SimplifiedType::Error),
+        ty::Bound(..) | ty::Infer(_) => None,
     }
 }
 
diff --git a/compiler/rustc_middle/src/ty/trait_def.rs b/compiler/rustc_middle/src/ty/trait_def.rs
index bf9b244936f..227a0753d04 100644
--- a/compiler/rustc_middle/src/ty/trait_def.rs
+++ b/compiler/rustc_middle/src/ty/trait_def.rs
@@ -1,6 +1,5 @@
 use crate::traits::specialization_graph;
 use crate::ty::fast_reject::{self, SimplifiedType, TreatParams, TreatProjections};
-use crate::ty::visit::TypeVisitableExt;
 use crate::ty::{Ident, Ty, TyCtxt};
 use hir::def_id::LOCAL_CRATE;
 use rustc_hir as hir;
@@ -241,9 +240,6 @@ pub(super) fn trait_impls_of_provider(tcx: TyCtxt<'_>, trait_id: DefId) -> Trait
         let impl_def_id = impl_def_id.to_def_id();
 
         let impl_self_ty = tcx.type_of(impl_def_id).instantiate_identity();
-        if impl_self_ty.references_error() {
-            continue;
-        }
 
         if let Some(simplified_self_ty) =
             fast_reject::simplify_type(tcx, impl_self_ty, TreatParams::AsCandidateKey)
diff --git a/compiler/rustc_trait_selection/src/traits/specialize/mod.rs b/compiler/rustc_trait_selection/src/traits/specialize/mod.rs
index 10329c623b3..200d022c80c 100644
--- a/compiler/rustc_trait_selection/src/traits/specialize/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/specialize/mod.rs
@@ -26,7 +26,7 @@ use rustc_middle::ty::{self, ImplSubject, Ty, TyCtxt, TypeVisitableExt};
 use rustc_middle::ty::{GenericArgs, GenericArgsRef};
 use rustc_session::lint::builtin::COHERENCE_LEAK_CHECK;
 use rustc_session::lint::builtin::ORDER_DEPENDENT_TRAIT_OBJECTS;
-use rustc_span::{Span, DUMMY_SP};
+use rustc_span::{ErrorGuaranteed, Span, DUMMY_SP};
 
 use super::util;
 use super::SelectionContext;
@@ -258,7 +258,7 @@ fn fulfill_implication<'tcx>(
 pub(super) fn specialization_graph_provider(
     tcx: TyCtxt<'_>,
     trait_id: DefId,
-) -> specialization_graph::Graph {
+) -> Result<&'_ specialization_graph::Graph, ErrorGuaranteed> {
     let mut sg = specialization_graph::Graph::new();
     let overlap_mode = specialization_graph::OverlapMode::get(tcx, trait_id);
 
@@ -271,6 +271,8 @@ pub(super) fn specialization_graph_provider(
     trait_impls
         .sort_unstable_by_key(|def_id| (-(def_id.krate.as_u32() as i64), def_id.index.index()));
 
+    let mut errored = Ok(());
+
     for impl_def_id in trait_impls {
         if let Some(impl_def_id) = impl_def_id.as_local() {
             // This is where impl overlap checking happens:
@@ -283,15 +285,21 @@ pub(super) fn specialization_graph_provider(
             };
 
             if let Some(overlap) = overlap {
-                report_overlap_conflict(tcx, overlap, impl_def_id, used_to_be_allowed, &mut sg);
+                errored = errored.and(report_overlap_conflict(
+                    tcx,
+                    overlap,
+                    impl_def_id,
+                    used_to_be_allowed,
+                ));
             }
         } else {
             let parent = tcx.impl_parent(impl_def_id).unwrap_or(trait_id);
             sg.record_impl_from_cstore(tcx, parent, impl_def_id)
         }
     }
+    errored?;
 
-    sg
+    Ok(tcx.arena.alloc(sg))
 }
 
 // This function is only used when
@@ -304,36 +312,31 @@ fn report_overlap_conflict<'tcx>(
     overlap: OverlapError<'tcx>,
     impl_def_id: LocalDefId,
     used_to_be_allowed: Option<FutureCompatOverlapErrorKind>,
-    sg: &mut specialization_graph::Graph,
-) {
+) -> Result<(), ErrorGuaranteed> {
     let impl_polarity = tcx.impl_polarity(impl_def_id.to_def_id());
     let other_polarity = tcx.impl_polarity(overlap.with_impl);
     match (impl_polarity, other_polarity) {
         (ty::ImplPolarity::Negative, ty::ImplPolarity::Positive) => {
-            report_negative_positive_conflict(
+            Err(report_negative_positive_conflict(
                 tcx,
                 &overlap,
                 impl_def_id,
                 impl_def_id.to_def_id(),
                 overlap.with_impl,
-                sg,
-            );
+            ))
         }
 
         (ty::ImplPolarity::Positive, ty::ImplPolarity::Negative) => {
-            report_negative_positive_conflict(
+            Err(report_negative_positive_conflict(
                 tcx,
                 &overlap,
                 impl_def_id,
                 overlap.with_impl,
                 impl_def_id.to_def_id(),
-                sg,
-            );
+            ))
         }
 
-        _ => {
-            report_conflicting_impls(tcx, overlap, impl_def_id, used_to_be_allowed, sg);
-        }
+        _ => report_conflicting_impls(tcx, overlap, impl_def_id, used_to_be_allowed),
     }
 }
 
@@ -343,16 +346,16 @@ fn report_negative_positive_conflict<'tcx>(
     local_impl_def_id: LocalDefId,
     negative_impl_def_id: DefId,
     positive_impl_def_id: DefId,
-    sg: &mut specialization_graph::Graph,
-) {
-    let err = tcx.dcx().create_err(NegativePositiveConflict {
-        impl_span: tcx.def_span(local_impl_def_id),
-        trait_desc: overlap.trait_ref,
-        self_ty: overlap.self_ty,
-        negative_impl_span: tcx.span_of_impl(negative_impl_def_id),
-        positive_impl_span: tcx.span_of_impl(positive_impl_def_id),
-    });
-    sg.has_errored = Some(err.emit());
+) -> ErrorGuaranteed {
+    tcx.dcx()
+        .create_err(NegativePositiveConflict {
+            impl_span: tcx.def_span(local_impl_def_id),
+            trait_desc: overlap.trait_ref,
+            self_ty: overlap.self_ty,
+            negative_impl_span: tcx.span_of_impl(negative_impl_def_id),
+            positive_impl_span: tcx.span_of_impl(positive_impl_def_id),
+        })
+        .emit()
 }
 
 fn report_conflicting_impls<'tcx>(
@@ -360,8 +363,7 @@ fn report_conflicting_impls<'tcx>(
     overlap: OverlapError<'tcx>,
     impl_def_id: LocalDefId,
     used_to_be_allowed: Option<FutureCompatOverlapErrorKind>,
-    sg: &mut specialization_graph::Graph,
-) {
+) -> Result<(), ErrorGuaranteed> {
     let impl_span = tcx.def_span(impl_def_id);
 
     // Work to be done after we've built the DiagnosticBuilder. We have to define it
@@ -429,14 +431,11 @@ fn report_conflicting_impls<'tcx>(
                 let mut err = tcx.dcx().struct_span_err(impl_span, msg);
                 err.code(error_code!(E0119));
                 decorate(tcx, &overlap, impl_span, &mut err);
-                Some(err.emit())
+                err.emit()
             } else {
-                Some(
-                    tcx.dcx()
-                        .span_delayed_bug(impl_span, "impl should have failed the orphan check"),
-                )
+                tcx.dcx().span_delayed_bug(impl_span, "impl should have failed the orphan check")
             };
-            sg.has_errored = reported;
+            Err(reported)
         }
         Some(kind) => {
             let lint = match kind {
@@ -452,8 +451,9 @@ fn report_conflicting_impls<'tcx>(
                     decorate(tcx, &overlap, impl_span, err);
                 },
             );
+            Ok(())
         }
-    };
+    }
 }
 
 /// Recovers the "impl X for Y" signature from `impl_def_id` and returns it as a
diff --git a/tests/ui/generic-associated-types/unknown-lifetime-ice-119827.rs b/tests/ui/generic-associated-types/unknown-lifetime-ice-119827.rs
new file mode 100644
index 00000000000..cd3acf9bc41
--- /dev/null
+++ b/tests/ui/generic-associated-types/unknown-lifetime-ice-119827.rs
@@ -0,0 +1,16 @@
+trait Foo {
+    type Context<'c>
+    where
+        Self: 'c;
+}
+
+impl Foo for Box<dyn Foo> {}
+//~^ ERROR `Foo` cannot be made into an object
+//~| ERROR `Foo` cannot be made into an object
+//~| ERROR cycle detected
+//~| ERROR cycle detected
+//~| ERROR cycle detected
+//~| ERROR the trait bound `Box<(dyn Foo + 'static)>: Foo` is not satisfied
+//~| ERROR not all trait items implemented
+
+fn main() {}
diff --git a/tests/ui/generic-associated-types/unknown-lifetime-ice-119827.stderr b/tests/ui/generic-associated-types/unknown-lifetime-ice-119827.stderr
new file mode 100644
index 00000000000..8e6b69f7461
--- /dev/null
+++ b/tests/ui/generic-associated-types/unknown-lifetime-ice-119827.stderr
@@ -0,0 +1,119 @@
+error[E0391]: cycle detected when computing type of `<impl at $DIR/unknown-lifetime-ice-119827.rs:7:1: 7:26>`
+  --> $DIR/unknown-lifetime-ice-119827.rs:7:1
+   |
+LL | impl Foo for Box<dyn Foo> {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: ...which requires finding trait impls of `Foo`...
+  --> $DIR/unknown-lifetime-ice-119827.rs:1:1
+   |
+LL | trait Foo {
+   | ^^^^^^^^^
+   = note: ...which again requires computing type of `<impl at $DIR/unknown-lifetime-ice-119827.rs:7:1: 7:26>`, completing the cycle
+note: cycle used when collecting item types in top-level module
+  --> $DIR/unknown-lifetime-ice-119827.rs:1:1
+   |
+LL | / trait Foo {
+LL | |     type Context<'c>
+LL | |     where
+LL | |         Self: 'c;
+...  |
+LL | |
+LL | | fn main() {}
+   | |____________^
+   = note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information
+
+error[E0391]: cycle detected when computing type of `<impl at $DIR/unknown-lifetime-ice-119827.rs:7:1: 7:26>`
+  --> $DIR/unknown-lifetime-ice-119827.rs:7:1
+   |
+LL | impl Foo for Box<dyn Foo> {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: ...which immediately requires computing type of `<impl at $DIR/unknown-lifetime-ice-119827.rs:7:1: 7:26>` again
+note: cycle used when collecting item types in top-level module
+  --> $DIR/unknown-lifetime-ice-119827.rs:1:1
+   |
+LL | / trait Foo {
+LL | |     type Context<'c>
+LL | |     where
+LL | |         Self: 'c;
+...  |
+LL | |
+LL | | fn main() {}
+   | |____________^
+   = note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information
+
+error[E0391]: cycle detected when computing type of `<impl at $DIR/unknown-lifetime-ice-119827.rs:7:1: 7:26>`
+  --> $DIR/unknown-lifetime-ice-119827.rs:7:1
+   |
+LL | impl Foo for Box<dyn Foo> {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: ...which immediately requires computing type of `<impl at $DIR/unknown-lifetime-ice-119827.rs:7:1: 7:26>` again
+note: cycle used when collecting item types in top-level module
+  --> $DIR/unknown-lifetime-ice-119827.rs:1:1
+   |
+LL | / trait Foo {
+LL | |     type Context<'c>
+LL | |     where
+LL | |         Self: 'c;
+...  |
+LL | |
+LL | | fn main() {}
+   | |____________^
+   = note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
+error[E0038]: the trait `Foo` cannot be made into an object
+  --> $DIR/unknown-lifetime-ice-119827.rs:7:22
+   |
+LL | impl Foo for Box<dyn Foo> {}
+   |                      ^^^ `Foo` cannot be made into an object
+   |
+note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
+  --> $DIR/unknown-lifetime-ice-119827.rs:2:10
+   |
+LL | trait Foo {
+   |       --- this trait cannot be made into an object...
+LL |     type Context<'c>
+   |          ^^^^^^^ ...because it contains the generic associated type `Context`
+   = help: consider moving `Context` to another trait
+   = help: only type `{type error}` implements the trait, consider using it directly instead
+
+error[E0277]: the trait bound `Box<(dyn Foo + 'static)>: Foo` is not satisfied
+  --> $DIR/unknown-lifetime-ice-119827.rs:7:14
+   |
+LL | impl Foo for Box<dyn Foo> {}
+   |              ^^^^^^^^^^^^ the trait `Foo` is not implemented for `Box<(dyn Foo + 'static)>`
+   |
+   = help: the trait `Foo` is implemented for `Box<(dyn Foo + 'static)>`
+
+error[E0038]: the trait `Foo` cannot be made into an object
+  --> $DIR/unknown-lifetime-ice-119827.rs:7:14
+   |
+LL | impl Foo for Box<dyn Foo> {}
+   |              ^^^^^^^^^^^^ `Foo` cannot be made into an object
+   |
+note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
+  --> $DIR/unknown-lifetime-ice-119827.rs:2:10
+   |
+LL | trait Foo {
+   |       --- this trait cannot be made into an object...
+LL |     type Context<'c>
+   |          ^^^^^^^ ...because it contains the generic associated type `Context`
+   = help: consider moving `Context` to another trait
+   = help: only type `std::boxed::Box<(dyn Foo + 'static)>` implements the trait, consider using it directly instead
+
+error[E0046]: not all trait items implemented, missing: `Context`
+  --> $DIR/unknown-lifetime-ice-119827.rs:7:1
+   |
+LL |     type Context<'c>
+   |     ---------------- `Context` from trait
+...
+LL | impl Foo for Box<dyn Foo> {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^ missing `Context` in implementation
+
+error: aborting due to 7 previous errors
+
+Some errors have detailed explanations: E0038, E0046, E0277, E0391.
+For more information about an error, try `rustc --explain E0038`.