Auto merge of #119879 - matthiaskrgr:rollup-y710der, r=matthiaskrgr

Rollup of 4 pull requests

Successful merges:

 - #119781 (fix typo)
 - #119865 (Set `c_str_literals` stabilization version back to `CURRENT_RUSTC_VERSION`)
 - #119866 (Convert `effects` description to doc comment)
 - #119868 (Register even erroneous impls)

r? `@ghost`
`@rustbot` modify labels: rollup

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,
         ]);
     )
 }

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 }
     }

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] {

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 {

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,
     }
 }
 

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)