Auto merge of #145142 - Zalathar:rollup-oi6s8kg, r=Zalathar

Rollup of 23 pull requests

Successful merges:

 - #141658 (rustdoc search: prefer stable items in search results)
 - #141828 (Add diagnostic explaining STATUS_STACK_BUFFER_OVERRUN not only being used for stack buffer overruns if link.exe exits with that exit code)
 - #144823 (coverage: Extract HIR-related helper code out of the main module)
 - #144883 (Remove unneeded `drop_in_place` calls)
 - #144923 (Move several more float tests to floats/mod.rs)
 - #144988 (Add annotations to the graphviz region graph on region origins)
 - #145010 (Couple of minor abi handling cleanups)
 - #145017 (Explicitly disable vector feature on s390x baseline of bad-reg test)
 - #145027 (Optimize `char::is_alphanumeric`)
 - #145050 (add member constraints tests)
 - #145073 (update enzyme submodule to handle llvm 21)
 - #145080 (Escape diff strings in MIR dataflow graphviz)
 - #145082 (Fix some bad formatting in `-Zmacro-stats` output.)
 - #145083 (Fix cross-compilation of Cargo)
 - #145096 (Fix wasm target build with atomics feature)
 - #145097 (remove unnecessary `TypeFoldable` impls)
 - #145100 (Rank doc aliases lower than equivalently matched items)
 - #145103 (rustc_metadata: remove unused private trait impls)
 - #145115 (defer opaque type errors, generally greatly reduce tainting)
 - #145119 (rustc_public: fix missing parenthesis in pretty discriminant)
 - #145124 (Recover `for PAT = EXPR {}`)
 - #145132 (Refactor map_unit_fn lint)
 - #145134 (Reduce indirect assoc parent queries)

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

Author: bors

compiler/rustc_borrowck/src/diagnostics/mod.rs

@@ -51,7 +51,7 @@ mod conflict_errors;
 mod explain_borrow;
 mod move_errors;
 mod mutability_errors;
-mod opaque_suggestions;
+mod opaque_types;
 mod region_errors;
 
 pub(crate) use bound_region_errors::{ToUniverseInfo, UniverseInfo};

compiler/rustc_borrowck/src/diagnostics/opaque_suggestions.rs renamed to compiler/rustc_borrowck/src/diagnostics/opaque_types.rs

@@ -18,9 +18,28 @@ use rustc_trait_selection::errors::impl_trait_overcapture_suggestion;
 use crate::MirBorrowckCtxt;
 use crate::borrow_set::BorrowData;
 use crate::consumers::RegionInferenceContext;
+use crate::region_infer::opaque_types::DeferredOpaqueTypeError;
 use crate::type_check::Locations;
 
 impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
+    pub(crate) fn report_opaque_type_errors(&mut self, errors: Vec<DeferredOpaqueTypeError<'tcx>>) {
+        if errors.is_empty() {
+            return;
+        }
+        let mut guar = None;
+        for error in errors {
+            guar = Some(match error {
+                DeferredOpaqueTypeError::InvalidOpaqueTypeArgs(err) => err.report(self.infcx),
+                DeferredOpaqueTypeError::LifetimeMismatchOpaqueParam(err) => {
+                    self.infcx.dcx().emit_err(err)
+                }
+            });
+        }
+        let guar = guar.unwrap();
+        self.root_cx.set_tainted_by_errors(guar);
+        self.infcx.set_tainted_by_errors(guar);
+    }
+
     /// Try to note when an opaque is involved in a borrowck error and that
     /// opaque captures lifetimes due to edition 2024.
     // FIXME: This code is otherwise somewhat general, and could easily be adapted

compiler/rustc_borrowck/src/diagnostics/region_errors.rs

@@ -92,9 +92,6 @@ impl<'tcx> RegionErrors<'tcx> {
     ) -> impl Iterator<Item = (RegionErrorKind<'tcx>, ErrorGuaranteed)> {
         self.0.into_iter()
     }
-    pub(crate) fn has_errors(&self) -> Option<ErrorGuaranteed> {
-        self.0.get(0).map(|x| x.1)
-    }
 }
 
 impl std::fmt::Debug for RegionErrors<'_> {

compiler/rustc_borrowck/src/handle_placeholders.rs

@@ -157,7 +157,7 @@ fn region_definitions<'tcx>(
     for info in var_infos.iter() {
         let origin = match info.origin {
             RegionVariableOrigin::Nll(origin) => origin,
-            _ => NllRegionVariableOrigin::Existential { from_forall: false },
+            _ => NllRegionVariableOrigin::Existential { from_forall: false, name: None },
         };
 
         let definition = RegionDefinition { origin, universe: info.universe, external_name: None };
@@ -216,22 +216,11 @@ pub(crate) fn compute_sccs_applying_placeholder_outlives_constraints<'tcx>(
         placeholder_index_to_region: _,
         liveness_constraints,
         mut outlives_constraints,
-        mut member_constraints,
+        member_constraints,
         universe_causes,
         type_tests,
     } = constraints;
 
-    if let Some(guar) = universal_regions.tainted_by_errors() {
-        debug!("Universal regions tainted by errors; removing constraints!");
-        // Suppress unhelpful extra errors in `infer_opaque_types` by clearing out all
-        // outlives bounds that we may end up checking.
-        outlives_constraints = Default::default();
-        member_constraints = Default::default();
-
-        // Also taint the entire scope.
-        infcx.set_tainted_by_errors(guar);
-    }
-
     let fr_static = universal_regions.fr_static;
     let compute_sccs =
         |constraints: &OutlivesConstraintSet<'tcx>,

compiler/rustc_borrowck/src/lib.rs

@@ -375,7 +375,7 @@ fn do_mir_borrowck<'tcx>(
         polonius_context,
     );
 
-    regioncx.infer_opaque_types(root_cx, &infcx, opaque_type_values);
+    let opaque_type_errors = regioncx.infer_opaque_types(root_cx, &infcx, opaque_type_values);
 
     // Dump MIR results into a file, if that is enabled. This lets us
     // write unit-tests, as well as helping with debugging.
@@ -471,7 +471,11 @@ fn do_mir_borrowck<'tcx>(
     };
 
     // Compute and report region errors, if any.
-    mbcx.report_region_errors(nll_errors);
+    if nll_errors.is_empty() {
+        mbcx.report_opaque_type_errors(opaque_type_errors);
+    } else {
+        mbcx.report_region_errors(nll_errors);
+    }
 
     let (mut flow_analysis, flow_entry_states) =
         get_flow_results(tcx, body, &move_data, &borrow_set, &regioncx);

compiler/rustc_borrowck/src/nll.rs

@@ -148,11 +148,6 @@ pub(crate) fn compute_regions<'tcx>(
     let (closure_region_requirements, nll_errors) =
         regioncx.solve(infcx, body, polonius_output.clone());
 
-    if let Some(guar) = nll_errors.has_errors() {
-        // Suppress unhelpful extra errors in `infer_opaque_types`.
-        infcx.set_tainted_by_errors(guar);
-    }
-
     NllOutput {
         regioncx,
         polonius_input: polonius_facts.map(Box::new),

compiler/rustc_borrowck/src/region_infer/graphviz.rs

@@ -41,7 +41,22 @@ fn render_region_vid<'tcx>(
         "".to_string()
     };
 
-    format!("{:?}{universe_str}{external_name_str}", rvid)
+    let extra_info = match regioncx.region_definition(rvid).origin {
+        NllRegionVariableOrigin::FreeRegion => "".to_string(),
+        NllRegionVariableOrigin::Placeholder(p) => match p.bound.kind {
+            ty::BoundRegionKind::Named(def_id) => {
+                format!(" (for<{}>)", tcx.item_name(def_id))
+            }
+            ty::BoundRegionKind::ClosureEnv | ty::BoundRegionKind::Anon => " (for<'_>)".to_string(),
+            ty::BoundRegionKind::NamedAnon(_) => {
+                bug!("only used for pretty printing")
+            }
+        },
+        NllRegionVariableOrigin::Existential { name: Some(name), .. } => format!(" (ex<{name}>)"),
+        NllRegionVariableOrigin::Existential { .. } => format!(" (ex<'_>)"),
+    };
+
+    format!("{:?}{universe_str}{external_name_str}{extra_info}", rvid)
 }
 
 impl<'tcx> RegionInferenceContext<'tcx> {

compiler/rustc_borrowck/src/region_infer/mod.rs

@@ -44,7 +44,7 @@ use crate::{
 
 mod dump_mir;
 mod graphviz;
-mod opaque_types;
+pub(crate) mod opaque_types;
 mod reverse_sccs;
 
 pub(crate) mod values;
@@ -1940,9 +1940,9 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         // and here we prefer to blame the source (the y = x statement).
         let blame_source = match from_region_origin {
             NllRegionVariableOrigin::FreeRegion
-            | NllRegionVariableOrigin::Existential { from_forall: false } => true,
+            | NllRegionVariableOrigin::Existential { from_forall: false, name: _ } => true,
             NllRegionVariableOrigin::Placeholder(_)
-            | NllRegionVariableOrigin::Existential { from_forall: true } => false,
+            | NllRegionVariableOrigin::Existential { from_forall: true, name: _ } => false,
         };
 
         // To pick a constraint to blame, we organize constraints by how interesting we expect them

compiler/rustc_borrowck/src/region_infer/opaque_types.rs

@@ -6,14 +6,21 @@ use rustc_middle::ty::{
     TypeVisitableExt, fold_regions,
 };
 use rustc_span::Span;
-use rustc_trait_selection::opaque_types::check_opaque_type_parameter_valid;
+use rustc_trait_selection::opaque_types::{
+    InvalidOpaqueTypeArgs, check_opaque_type_parameter_valid,
+};
 use tracing::{debug, instrument};
 
 use super::RegionInferenceContext;
 use crate::BorrowCheckRootCtxt;
 use crate::session_diagnostics::LifetimeMismatchOpaqueParam;
 use crate::universal_regions::RegionClassification;
 
+pub(crate) enum DeferredOpaqueTypeError<'tcx> {
+    InvalidOpaqueTypeArgs(InvalidOpaqueTypeArgs<'tcx>),
+    LifetimeMismatchOpaqueParam(LifetimeMismatchOpaqueParam<'tcx>),
+}
+
 impl<'tcx> RegionInferenceContext<'tcx> {
     /// Resolve any opaque types that were encountered while borrow checking
     /// this item. This is then used to get the type in the `type_of` query.
@@ -58,13 +65,14 @@ impl<'tcx> RegionInferenceContext<'tcx> {
     ///
     /// [rustc-dev-guide chapter]:
     /// https://rustc-dev-guide.rust-lang.org/opaque-types-region-infer-restrictions.html
-    #[instrument(level = "debug", skip(self, root_cx, infcx), ret)]
+    #[instrument(level = "debug", skip(self, root_cx, infcx))]
     pub(crate) fn infer_opaque_types(
         &self,
         root_cx: &mut BorrowCheckRootCtxt<'tcx>,
         infcx: &InferCtxt<'tcx>,
         opaque_ty_decls: FxIndexMap<OpaqueTypeKey<'tcx>, OpaqueHiddenType<'tcx>>,
-    ) {
+    ) -> Vec<DeferredOpaqueTypeError<'tcx>> {
+        let mut errors = Vec::new();
         let mut decls_modulo_regions: FxIndexMap<OpaqueTypeKey<'tcx>, (OpaqueTypeKey<'tcx>, Span)> =
             FxIndexMap::default();
 
@@ -124,8 +132,15 @@ impl<'tcx> RegionInferenceContext<'tcx> {
             });
             debug!(?concrete_type);
 
-            let ty =
-                infcx.infer_opaque_definition_from_instantiation(opaque_type_key, concrete_type);
+            let ty = match infcx
+                .infer_opaque_definition_from_instantiation(opaque_type_key, concrete_type)
+            {
+                Ok(ty) => ty,
+                Err(err) => {
+                    errors.push(DeferredOpaqueTypeError::InvalidOpaqueTypeArgs(err));
+                    continue;
+                }
+            };
 
             // Sometimes, when the hidden type is an inference variable, it can happen that
             // the hidden type becomes the opaque type itself. In this case, this was an opaque
@@ -149,25 +164,27 @@ impl<'tcx> RegionInferenceContext<'tcx> {
             // non-region parameters. This is necessary because within the new solver we perform
             // various query operations modulo regions, and thus could unsoundly select some impls
             // that don't hold.
-            if !ty.references_error()
-                && let Some((prev_decl_key, prev_span)) = decls_modulo_regions.insert(
-                    infcx.tcx.erase_regions(opaque_type_key),
-                    (opaque_type_key, concrete_type.span),
-                )
-                && let Some((arg1, arg2)) = std::iter::zip(
-                    prev_decl_key.iter_captured_args(infcx.tcx).map(|(_, arg)| arg),
-                    opaque_type_key.iter_captured_args(infcx.tcx).map(|(_, arg)| arg),
-                )
-                .find(|(arg1, arg2)| arg1 != arg2)
+            if let Some((prev_decl_key, prev_span)) = decls_modulo_regions.insert(
+                infcx.tcx.erase_regions(opaque_type_key),
+                (opaque_type_key, concrete_type.span),
+            ) && let Some((arg1, arg2)) = std::iter::zip(
+                prev_decl_key.iter_captured_args(infcx.tcx).map(|(_, arg)| arg),
+                opaque_type_key.iter_captured_args(infcx.tcx).map(|(_, arg)| arg),
+            )
+            .find(|(arg1, arg2)| arg1 != arg2)
             {
-                infcx.dcx().emit_err(LifetimeMismatchOpaqueParam {
-                    arg: arg1,
-                    prev: arg2,
-                    span: prev_span,
-                    prev_span: concrete_type.span,
-                });
+                errors.push(DeferredOpaqueTypeError::LifetimeMismatchOpaqueParam(
+                    LifetimeMismatchOpaqueParam {
+                        arg: arg1,
+                        prev: arg2,
+                        span: prev_span,
+                        prev_span: concrete_type.span,
+                    },
+                ));
             }
         }
+
+        errors
     }
 
     /// Map the regions in the type to named regions. This is similar to what
@@ -260,19 +277,13 @@ impl<'tcx> InferCtxt<'tcx> {
         &self,
         opaque_type_key: OpaqueTypeKey<'tcx>,
         instantiated_ty: OpaqueHiddenType<'tcx>,
-    ) -> Ty<'tcx> {
-        if let Some(e) = self.tainted_by_errors() {
-            return Ty::new_error(self.tcx, e);
-        }
-
-        if let Err(err) = check_opaque_type_parameter_valid(
+    ) -> Result<Ty<'tcx>, InvalidOpaqueTypeArgs<'tcx>> {
+        check_opaque_type_parameter_valid(
             self,
             opaque_type_key,
             instantiated_ty.span,
             DefiningScopeKind::MirBorrowck,
-        ) {
-            return Ty::new_error(self.tcx, err.report(self));
-        }
+        )?;
 
         let definition_ty = instantiated_ty
             .remap_generic_params_to_declaration_params(
@@ -282,10 +293,7 @@ impl<'tcx> InferCtxt<'tcx> {
             )
             .ty;
 
-        if let Err(e) = definition_ty.error_reported() {
-            return Ty::new_error(self.tcx, e);
-        }
-
-        definition_ty
+        definition_ty.error_reported()?;
+        Ok(definition_ty)
     }
 }

compiler/rustc_borrowck/src/renumber.rs

@@ -66,7 +66,7 @@ impl<'a, 'tcx> RegionRenumberer<'a, 'tcx> {
         T: TypeFoldable<TyCtxt<'tcx>>,
         F: Fn() -> RegionCtxt,
     {
-        let origin = NllRegionVariableOrigin::Existential { from_forall: false };
+        let origin = NllRegionVariableOrigin::Existential { from_forall: false, name: None };
         fold_regions(self.infcx.tcx, value, |_region, _depth| {
             self.infcx.next_nll_region_var(origin, || region_ctxt_fn())
         })