Auto merge of #136038 - compiler-errors:outlives, r=lcnr

Simplify and consolidate the way we handle construct `OutlivesEnvironment` for lexical region resolution

This is best reviewed commit-by-commit. I tried to consolidate the API for lexical region resolution *first*, then change the API when it was finally behind a single surface.

r? lcnr or reassign

compiler/rustc_borrowck/src/region_infer/opaque_types.rs

@@ -1,6 +1,8 @@
 use rustc_data_structures::fx::FxIndexMap;
 use rustc_errors::ErrorGuaranteed;
+use rustc_hir::OpaqueTyOrigin;
 use rustc_hir::def_id::LocalDefId;
+use rustc_infer::infer::outlives::env::OutlivesEnvironment;
 use rustc_infer::infer::{InferCtxt, NllRegionVariableOrigin, TyCtxtInferExt as _};
 use rustc_macros::extension;
 use rustc_middle::ty::fold::fold_regions;
@@ -10,6 +12,7 @@ use rustc_middle::ty::{
     TypingMode,
 };
 use rustc_span::Span;
+use rustc_trait_selection::regions::OutlivesEnvironmentBuildExt;
 use rustc_trait_selection::traits::ObligationCtxt;
 use tracing::{debug, instrument};
 
@@ -406,10 +409,6 @@ impl<'tcx> LazyOpaqueTyEnv<'tcx> {
     }
 
     fn get_canonical_args(&self) -> ty::GenericArgsRef<'tcx> {
-        use rustc_hir as hir;
-        use rustc_infer::infer::outlives::env::OutlivesEnvironment;
-        use rustc_trait_selection::traits::outlives_bounds::InferCtxtExt as _;
-
         if let Some(&canonical_args) = self.canonical_args.get() {
             return canonical_args;
         }
@@ -417,9 +416,9 @@ impl<'tcx> LazyOpaqueTyEnv<'tcx> {
         let &Self { tcx, def_id, .. } = self;
         let origin = tcx.local_opaque_ty_origin(def_id);
         let parent = match origin {
-            hir::OpaqueTyOrigin::FnReturn { parent, .. }
+            OpaqueTyOrigin::FnReturn { parent, .. }
-            | hir::OpaqueTyOrigin::AsyncFn { parent, .. }
+            | OpaqueTyOrigin::AsyncFn { parent, .. }
-            | hir::OpaqueTyOrigin::TyAlias { parent, .. } => parent,
+            | OpaqueTyOrigin::TyAlias { parent, .. } => parent,
         };
         let param_env = tcx.param_env(parent);
         let args = GenericArgs::identity_for_item(tcx, parent).extend_to(
@@ -439,8 +438,7 @@ impl<'tcx> LazyOpaqueTyEnv<'tcx> {
             tcx.dcx().span_delayed_bug(tcx.def_span(def_id), "error getting implied bounds");
             Default::default()
         });
-        let implied_bounds = infcx.implied_bounds_tys(param_env, parent, &wf_tys);
+        let outlives_env = OutlivesEnvironment::new(&infcx, parent, param_env, wf_tys);
-        let outlives_env = OutlivesEnvironment::with_bounds(param_env, implied_bounds);
 
         let mut seen = vec![tcx.lifetimes.re_static];
         let canonical_args = fold_regions(tcx, args, |r1, _| {

compiler/rustc_hir_analysis/src/check/check.rs

@@ -27,7 +27,6 @@ use rustc_session::lint::builtin::UNINHABITED_STATIC;
 use rustc_trait_selection::error_reporting::InferCtxtErrorExt;
 use rustc_trait_selection::error_reporting::traits::on_unimplemented::OnUnimplementedDirective;
 use rustc_trait_selection::traits;
-use rustc_trait_selection::traits::outlives_bounds::InferCtxtExt as _;
 use rustc_type_ir::fold::TypeFoldable;
 use tracing::{debug, instrument};
 use ty::TypingMode;
@@ -417,9 +416,7 @@ fn check_opaque_meets_bounds<'tcx>(
     }
 
     let wf_tys = ocx.assumed_wf_types_and_report_errors(param_env, defining_use_anchor)?;
-    let implied_bounds = infcx.implied_bounds_tys(param_env, def_id, &wf_tys);
+    ocx.resolve_regions_and_report_errors(defining_use_anchor, param_env, wf_tys)?;
-    let outlives_env = OutlivesEnvironment::with_bounds(param_env, implied_bounds);
-    ocx.resolve_regions_and_report_errors(defining_use_anchor, &outlives_env)?;
 
     if infcx.next_trait_solver() {
         Ok(())

compiler/rustc_hir_analysis/src/check/compare_impl_item.rs

@@ -9,7 +9,6 @@ use rustc_errors::{Applicability, ErrorGuaranteed, pluralize, struct_span_code_e
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::intravisit::VisitorExt;
 use rustc_hir::{self as hir, AmbigArg, GenericParamKind, ImplItemKind, intravisit};
-use rustc_infer::infer::outlives::env::OutlivesEnvironment;
 use rustc_infer::infer::{self, InferCtxt, TyCtxtInferExt};
 use rustc_infer::traits::util;
 use rustc_middle::ty::error::{ExpectedFound, TypeError};
@@ -24,7 +23,6 @@ use rustc_span::Span;
 use rustc_trait_selection::error_reporting::InferCtxtErrorExt;
 use rustc_trait_selection::infer::InferCtxtExt;
 use rustc_trait_selection::regions::InferCtxtRegionExt;
-use rustc_trait_selection::traits::outlives_bounds::InferCtxtExt as _;
 use rustc_trait_selection::traits::{
     self, FulfillmentError, ObligationCause, ObligationCauseCode, ObligationCtxt,
 };
@@ -416,11 +414,7 @@ fn compare_method_predicate_entailment<'tcx>(
 
     // Finally, resolve all regions. This catches wily misuses of
     // lifetime parameters.
-    let outlives_env = OutlivesEnvironment::with_bounds(
+    let errors = infcx.resolve_regions(impl_m_def_id, param_env, wf_tys);
-        param_env,
-        infcx.implied_bounds_tys(param_env, impl_m_def_id, &wf_tys),
-    );
-    let errors = infcx.resolve_regions(&outlives_env);
     if !errors.is_empty() {
         return Err(infcx
             .tainted_by_errors()
@@ -725,11 +719,7 @@ pub(super) fn collect_return_position_impl_trait_in_trait_tys<'tcx>(
 
     // Finally, resolve all regions. This catches wily misuses of
     // lifetime parameters.
-    let outlives_env = OutlivesEnvironment::with_bounds(
+    ocx.resolve_regions_and_report_errors(impl_m_def_id, param_env, wf_tys)?;
-        param_env,
-        infcx.implied_bounds_tys(param_env, impl_m_def_id, &wf_tys),
-    );
-    ocx.resolve_regions_and_report_errors(impl_m_def_id, &outlives_env)?;
 
     let mut remapped_types = DefIdMap::default();
     for (def_id, (ty, args)) in collected_types {
@@ -1883,8 +1873,7 @@ fn compare_const_predicate_entailment<'tcx>(
         return Err(infcx.err_ctxt().report_fulfillment_errors(errors));
     }
 
-    let outlives_env = OutlivesEnvironment::new(param_env);
+    ocx.resolve_regions_and_report_errors(impl_ct_def_id, param_env, [])
-    ocx.resolve_regions_and_report_errors(impl_ct_def_id, &outlives_env)
 }
 
 #[instrument(level = "debug", skip(tcx))]
@@ -2017,8 +2006,7 @@ fn compare_type_predicate_entailment<'tcx>(
 
     // Finally, resolve all regions. This catches wily misuses of
     // lifetime parameters.
-    let outlives_env = OutlivesEnvironment::new(param_env);
+    ocx.resolve_regions_and_report_errors(impl_ty_def_id, param_env, [])
-    ocx.resolve_regions_and_report_errors(impl_ty_def_id, &outlives_env)
 }
 
 /// Validate that `ProjectionCandidate`s created for this associated type will
@@ -2147,9 +2135,7 @@ pub(super) fn check_type_bounds<'tcx>(
 
     // Finally, resolve all regions. This catches wily misuses of
     // lifetime parameters.
-    let implied_bounds = infcx.implied_bounds_tys(param_env, impl_ty_def_id, &assumed_wf_types);
+    ocx.resolve_regions_and_report_errors(impl_ty_def_id, param_env, assumed_wf_types)
-    let outlives_env = OutlivesEnvironment::with_bounds(param_env, implied_bounds);
-    ocx.resolve_regions_and_report_errors(impl_ty_def_id, &outlives_env)
 }
 
 struct ReplaceTy<'tcx> {

compiler/rustc_hir_analysis/src/check/compare_impl_item/refine.rs

@@ -3,7 +3,6 @@ use rustc_data_structures::fx::FxIndexSet;
 use rustc_hir as hir;
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_infer::infer::TyCtxtInferExt;
-use rustc_infer::infer::outlives::env::OutlivesEnvironment;
 use rustc_lint_defs::builtin::{REFINING_IMPL_TRAIT_INTERNAL, REFINING_IMPL_TRAIT_REACHABLE};
 use rustc_middle::span_bug;
 use rustc_middle::traits::ObligationCause;
@@ -13,7 +12,6 @@ use rustc_middle::ty::{
 };
 use rustc_span::Span;
 use rustc_trait_selection::regions::InferCtxtRegionExt;
-use rustc_trait_selection::traits::outlives_bounds::InferCtxtExt;
 use rustc_trait_selection::traits::{ObligationCtxt, elaborate, normalize_param_env_or_error};
 
 /// Check that an implementation does not refine an RPITIT from a trait method signature.
@@ -170,11 +168,7 @@ pub(crate) fn check_refining_return_position_impl_trait_in_trait<'tcx>(
         tcx.dcx().delayed_bug("encountered errors when checking RPITIT refinement (selection)");
         return;
     }
-    let outlives_env = OutlivesEnvironment::with_bounds(
+    let errors = infcx.resolve_regions(impl_m.def_id.expect_local(), param_env, implied_wf_types);
-        param_env,
-        infcx.implied_bounds_tys(param_env, impl_m.def_id.expect_local(), &implied_wf_types),
-    );
-    let errors = infcx.resolve_regions(&outlives_env);
     if !errors.is_empty() {
         tcx.dcx().delayed_bug("encountered errors when checking RPITIT refinement (regions)");
         return;

compiler/rustc_hir_analysis/src/check/dropck.rs

@@ -5,7 +5,6 @@
 use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::codes::*;
 use rustc_errors::{ErrorGuaranteed, struct_span_code_err};
-use rustc_infer::infer::outlives::env::OutlivesEnvironment;
 use rustc_infer::infer::{RegionResolutionError, TyCtxtInferExt};
 use rustc_infer::traits::{ObligationCause, ObligationCauseCode};
 use rustc_middle::ty::util::CheckRegions;
@@ -192,7 +191,7 @@ fn ensure_drop_predicates_are_implied_by_item_defn<'tcx>(
         return Err(guar.unwrap());
     }
 
-    let errors = ocx.infcx.resolve_regions(&OutlivesEnvironment::new(adt_env));
+    let errors = ocx.infcx.resolve_regions(adt_def_id, adt_env, []);
     if !errors.is_empty() {
         let mut guar = None;
         for error in errors {

compiler/rustc_hir_analysis/src/check/mod.rs

@@ -80,7 +80,6 @@ use rustc_errors::{Diag, ErrorGuaranteed, pluralize, struct_span_code_err};
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::intravisit::Visitor;
 use rustc_index::bit_set::DenseBitSet;
-use rustc_infer::infer::outlives::env::OutlivesEnvironment;
 use rustc_infer::infer::{self, TyCtxtInferExt as _};
 use rustc_infer::traits::ObligationCause;
 use rustc_middle::query::Providers;
@@ -655,8 +654,7 @@ pub fn check_function_signature<'tcx>(
         }
     }
 
-    let outlives_env = OutlivesEnvironment::new(param_env);
+    if let Err(e) = ocx.resolve_regions_and_report_errors(local_id, param_env, []) {
-    if let Err(e) = ocx.resolve_regions_and_report_errors(local_id, &outlives_env) {
         return Err(e);
     }
 

compiler/rustc_hir_analysis/src/check/wfcheck.rs

@@ -25,11 +25,10 @@ use rustc_middle::{bug, span_bug};
 use rustc_session::parse::feature_err;
 use rustc_span::{DUMMY_SP, Ident, Span, sym};
 use rustc_trait_selection::error_reporting::InferCtxtErrorExt;
-use rustc_trait_selection::regions::InferCtxtRegionExt;
+use rustc_trait_selection::regions::{InferCtxtRegionExt, OutlivesEnvironmentBuildExt};
 use rustc_trait_selection::traits::misc::{
     ConstParamTyImplementationError, type_allowed_to_implement_const_param_ty,
 };
-use rustc_trait_selection::traits::outlives_bounds::InferCtxtExt as _;
 use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt as _;
 use rustc_trait_selection::traits::{
     self, FulfillmentError, Obligation, ObligationCause, ObligationCauseCode, ObligationCtxt,
@@ -128,13 +127,17 @@ where
     let infcx_compat = infcx.fork();
 
     // We specifically want to call the non-compat version of `implied_bounds_tys`; we do this always.
-    let implied_bounds =
+    let outlives_env = OutlivesEnvironment::new_with_implied_bounds_compat(
-        infcx.implied_bounds_tys_compat(param_env, body_def_id, &assumed_wf_types, false);
+        &infcx,
-    let outlives_env = OutlivesEnvironment::with_bounds(param_env, implied_bounds);
+        body_def_id,
+        param_env,
+        assumed_wf_types.iter().copied(),
+        false,
+    );
 
     lint_redundant_lifetimes(tcx, body_def_id, &outlives_env);
 
-    let errors = infcx.resolve_regions(&outlives_env);
+    let errors = infcx.resolve_regions_with_outlives_env(&outlives_env);
     if errors.is_empty() {
         return Ok(());
     }
@@ -172,10 +175,14 @@ where
     // but that does result in slightly more work when this option is set and
     // just obscures what we mean here anyways. Let's just be explicit.
     if is_bevy && !infcx.tcx.sess.opts.unstable_opts.no_implied_bounds_compat {
-        let implied_bounds =
+        let outlives_env = OutlivesEnvironment::new_with_implied_bounds_compat(
-            infcx_compat.implied_bounds_tys_compat(param_env, body_def_id, &assumed_wf_types, true);
+            &infcx,
-        let outlives_env = OutlivesEnvironment::with_bounds(param_env, implied_bounds);
+            body_def_id,
-        let errors_compat = infcx_compat.resolve_regions(&outlives_env);
+            param_env,
+            assumed_wf_types,
+            true,
+        );
+        let errors_compat = infcx_compat.resolve_regions_with_outlives_env(&outlives_env);
         if errors_compat.is_empty() {
             Ok(())
         } else {
@@ -769,12 +776,7 @@ fn test_region_obligations<'tcx>(
 
     add_constraints(&infcx);
 
-    let outlives_environment = OutlivesEnvironment::with_bounds(
+    let errors = infcx.resolve_regions(id, param_env, wf_tys.iter().copied());
-        param_env,
-        infcx.implied_bounds_tys(param_env, id, wf_tys),
-    );
-
-    let errors = infcx.resolve_regions(&outlives_environment);
     debug!(?errors, "errors");
 
     // If we were able to prove that the type outlives the region without

compiler/rustc_hir_analysis/src/coherence/builtin.rs

@@ -10,7 +10,6 @@ use rustc_hir as hir;
 use rustc_hir::ItemKind;
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::lang_items::LangItem;
-use rustc_infer::infer::outlives::env::OutlivesEnvironment;
 use rustc_infer::infer::{self, RegionResolutionError, TyCtxtInferExt};
 use rustc_infer::traits::Obligation;
 use rustc_middle::ty::adjustment::CoerceUnsizedInfo;
@@ -346,8 +345,7 @@ fn visit_implementation_of_dispatch_from_dyn(checker: &Checker<'_>) -> Result<()
                 }
 
                 // Finally, resolve all regions.
-                let outlives_env = OutlivesEnvironment::new(param_env);
+                res = res.and(ocx.resolve_regions_and_report_errors(impl_did, param_env, []));
-                res = res.and(ocx.resolve_regions_and_report_errors(impl_did, &outlives_env));
             }
             res
         }
@@ -564,8 +562,7 @@ pub(crate) fn coerce_unsized_info<'tcx>(
     }
 
     // Finally, resolve all regions.
-    let outlives_env = OutlivesEnvironment::new(param_env);
+    let _ = ocx.resolve_regions_and_report_errors(impl_did, param_env, []);
-    let _ = ocx.resolve_regions_and_report_errors(impl_did, &outlives_env);
 
     Ok(CoerceUnsizedInfo { custom_kind: kind })
 }

compiler/rustc_hir_analysis/src/impl_wf_check/min_specialization.rs

@@ -68,7 +68,6 @@
 use rustc_data_structures::fx::FxHashSet;
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_infer::infer::TyCtxtInferExt;
-use rustc_infer::infer::outlives::env::OutlivesEnvironment;
 use rustc_infer::traits::ObligationCause;
 use rustc_infer::traits::specialization_graph::Node;
 use rustc_middle::ty::trait_def::TraitSpecializationKind;
@@ -77,7 +76,6 @@ use rustc_middle::ty::{
 };
 use rustc_span::{ErrorGuaranteed, Span};
 use rustc_trait_selection::error_reporting::InferCtxtErrorExt;
-use rustc_trait_selection::traits::outlives_bounds::InferCtxtExt as _;
 use rustc_trait_selection::traits::{self, ObligationCtxt, translate_args_with_cause, wf};
 use tracing::{debug, instrument};
 
@@ -176,7 +174,6 @@ fn get_impl_args(
     let ocx = ObligationCtxt::new_with_diagnostics(infcx);
     let param_env = tcx.param_env(impl1_def_id);
     let impl1_span = tcx.def_span(impl1_def_id);
-    let assumed_wf_types = ocx.assumed_wf_types_and_report_errors(param_env, impl1_def_id)?;
 
     let impl1_args = GenericArgs::identity_for_item(tcx, impl1_def_id);
     let impl2_args = translate_args_with_cause(
@@ -194,9 +191,8 @@ fn get_impl_args(
         return Err(guar);
     }
 
-    let implied_bounds = infcx.implied_bounds_tys(param_env, impl1_def_id, &assumed_wf_types);
+    let assumed_wf_types = ocx.assumed_wf_types_and_report_errors(param_env, impl1_def_id)?;
-    let outlives_env = OutlivesEnvironment::with_bounds(param_env, implied_bounds);
+    let _ = ocx.resolve_regions_and_report_errors(impl1_def_id, param_env, assumed_wf_types);
-    let _ = ocx.resolve_regions_and_report_errors(impl1_def_id, &outlives_env);
     let Ok(impl2_args) = infcx.fully_resolve(impl2_args) else {
         let span = tcx.def_span(impl1_def_id);
         let guar = tcx.dcx().emit_err(GenericArgsOnOverriddenImpl { span });

compiler/rustc_infer/src/infer/outlives/env.rs

@@ -31,26 +31,14 @@ use crate::traits::query::OutlivesBound;
 pub struct OutlivesEnvironment<'tcx> {
     pub param_env: ty::ParamEnv<'tcx>,
     free_region_map: FreeRegionMap<'tcx>,
-
+    /// FIXME: Your first reaction may be that this is a bit strange. `RegionBoundPairs`
-    // Contains the implied region bounds in scope for our current body.
+    /// does not contain lifetimes, which are instead in the `FreeRegionMap`, and other
-    //
+    /// known type outlives are stored in the `known_type_outlives` set. So why do we
-    // Example:
+    /// have these at all? It turns out that removing these and using `known_type_outlives`
-    //
+    /// everywhere is just enough of a perf regression to matter. This can/should be
-    // ```
+    /// optimized in the future, though.
-    // fn foo<'a, 'b, T>(x: &'a T, y: &'b ()) {
-    //   bar(x, y, |y: &'b T| { .. } // body B1)
-    // } // body B0
-    // ```
-    //
-    // Here, when checking the body B0, the list would be `[T: 'a]`, because we
-    // infer that `T` must outlive `'a` from the implied bounds on the
-    // fn declaration.
-    //
-    // For the body B1 however, the list would be `[T: 'a, T: 'b]`, because we
-    // also can see that -- within the closure body! -- `T` must
-    // outlive `'b`. This is not necessarily true outside the closure
-    // body, since the closure may never be called.
     region_bound_pairs: RegionBoundPairs<'tcx>,
+    known_type_outlives: Vec<ty::PolyTypeOutlivesPredicate<'tcx>>,
 }
 
 /// "Region-bound pairs" tracks outlives relations that are known to
@@ -59,15 +47,10 @@ pub struct OutlivesEnvironment<'tcx> {
 pub type RegionBoundPairs<'tcx> = FxIndexSet<ty::OutlivesPredicate<'tcx, GenericKind<'tcx>>>;
 
 impl<'tcx> OutlivesEnvironment<'tcx> {
-    /// Create a new `OutlivesEnvironment` without extra outlives bounds.
+    /// Create a new `OutlivesEnvironment` from normalized outlives bounds.
-    #[inline]
+    pub fn from_normalized_bounds(
-    pub fn new(param_env: ty::ParamEnv<'tcx>) -> Self {
-        Self::with_bounds(param_env, vec![])
-    }
-
-    /// Create a new `OutlivesEnvironment` with extra outlives bounds.
-    pub fn with_bounds(
         param_env: ty::ParamEnv<'tcx>,
+        known_type_outlives: Vec<ty::PolyTypeOutlivesPredicate<'tcx>>,
         extra_bounds: impl IntoIterator<Item = OutlivesBound<'tcx>>,
     ) -> Self {
         let mut region_relation = TransitiveRelationBuilder::default();
@@ -102,18 +85,21 @@ impl<'tcx> OutlivesEnvironment<'tcx> {
 
         OutlivesEnvironment {
             param_env,
+            known_type_outlives,
             free_region_map: FreeRegionMap { relation: region_relation.freeze() },
             region_bound_pairs,
         }
     }
 
-    /// Borrows current value of the `free_region_map`.
     pub fn free_region_map(&self) -> &FreeRegionMap<'tcx> {
         &self.free_region_map
     }
 
-    /// Borrows current `region_bound_pairs`.
     pub fn region_bound_pairs(&self) -> &RegionBoundPairs<'tcx> {
         &self.region_bound_pairs
     }
+
+    pub fn known_type_outlives(&self) -> &[ty::PolyTypeOutlivesPredicate<'tcx>] {
+        &self.known_type_outlives
+    }
 }

compiler/rustc_infer/src/infer/outlives/obligations.rs

@@ -67,7 +67,6 @@ use rustc_middle::ty::{
     self, GenericArgKind, GenericArgsRef, PolyTypeOutlivesPredicate, Region, Ty, TyCtxt,
     TypeFoldable as _, TypeVisitableExt,
 };
-use rustc_span::DUMMY_SP;
 use rustc_type_ir::outlives::{Component, push_outlives_components};
 use smallvec::smallvec;
 use tracing::{debug, instrument};
@@ -142,25 +141,6 @@ impl<'tcx> InferCtxt<'tcx> {
     ) -> Result<(), (PolyTypeOutlivesPredicate<'tcx>, SubregionOrigin<'tcx>)> {
         assert!(!self.in_snapshot(), "cannot process registered region obligations in a snapshot");
 
-        let normalized_caller_bounds: Vec<_> = outlives_env
-            .param_env
-            .caller_bounds()
-            .iter()
-            .filter_map(|clause| {
-                let outlives = clause.as_type_outlives_clause()?;
-                Some(
-                    deeply_normalize_ty(
-                        outlives,
-                        SubregionOrigin::AscribeUserTypeProvePredicate(DUMMY_SP),
-                    )
-                    // FIXME(-Znext-solver): How do we accurately report an error span here :(
-                    .map_err(|NoSolution| {
-                        (outlives, SubregionOrigin::AscribeUserTypeProvePredicate(DUMMY_SP))
-                    }),
-                )
-            })
-            .try_collect()?;
-
         // Must loop since the process of normalizing may itself register region obligations.
         for iteration in 0.. {
             let my_region_obligations = self.take_registered_region_obligations();
@@ -194,7 +174,7 @@ impl<'tcx> InferCtxt<'tcx> {
                     self.tcx,
                     outlives_env.region_bound_pairs(),
                     None,
-                    &normalized_caller_bounds,
+                    outlives_env.known_type_outlives(),
                 );
                 let category = origin.to_constraint_category();
                 outlives.type_must_outlive(origin, sup_type, sub_region, category);

compiler/rustc_lint/src/impl_trait_overcaptures.rs

@@ -25,8 +25,8 @@ use rustc_span::{Span, Symbol};
 use rustc_trait_selection::errors::{
     AddPreciseCapturingForOvercapture, impl_trait_overcapture_suggestion,
 };
+use rustc_trait_selection::regions::OutlivesEnvironmentBuildExt;
 use rustc_trait_selection::traits::ObligationCtxt;
-use rustc_trait_selection::traits::outlives_bounds::InferCtxtExt;
 
 use crate::{LateContext, LateLintPass, fluent_generated as fluent};
 
@@ -190,9 +190,7 @@ fn check_fn(tcx: TyCtxt<'_>, parent_def_id: LocalDefId) {
             let (infcx, param_env) = tcx.infer_ctxt().build_with_typing_env(typing_env);
             let ocx = ObligationCtxt::new(&infcx);
             let assumed_wf_tys = ocx.assumed_wf_types(param_env, parent_def_id).unwrap_or_default();
-            let implied_bounds =
+            OutlivesEnvironment::new(&infcx, parent_def_id, param_env, assumed_wf_tys)
-                infcx.implied_bounds_tys_compat(param_env, parent_def_id, &assumed_wf_tys, false);
-            OutlivesEnvironment::with_bounds(param_env, implied_bounds)
         }),
     });
 }

compiler/rustc_trait_selection/src/regions.rs

@@ -1,10 +1,73 @@
+use rustc_hir::def_id::LocalDefId;
 use rustc_infer::infer::outlives::env::OutlivesEnvironment;
 use rustc_infer::infer::{InferCtxt, RegionResolutionError};
 use rustc_macros::extension;
 use rustc_middle::traits::ObligationCause;
 use rustc_middle::traits::query::NoSolution;
+use rustc_middle::ty::{self, Ty};
 
 use crate::traits::ScrubbedTraitError;
+use crate::traits::outlives_bounds::InferCtxtExt;
+
+#[extension(pub trait OutlivesEnvironmentBuildExt<'tcx>)]
+impl<'tcx> OutlivesEnvironment<'tcx> {
+    fn new(
+        infcx: &InferCtxt<'tcx>,
+        body_id: LocalDefId,
+        param_env: ty::ParamEnv<'tcx>,
+        assumed_wf_tys: impl IntoIterator<Item = Ty<'tcx>>,
+    ) -> Self {
+        Self::new_with_implied_bounds_compat(
+            infcx,
+            body_id,
+            param_env,
+            assumed_wf_tys,
+            !infcx.tcx.sess.opts.unstable_opts.no_implied_bounds_compat,
+        )
+    }
+
+    fn new_with_implied_bounds_compat(
+        infcx: &InferCtxt<'tcx>,
+        body_id: LocalDefId,
+        param_env: ty::ParamEnv<'tcx>,
+        assumed_wf_tys: impl IntoIterator<Item = Ty<'tcx>>,
+        implied_bounds_compat: bool,
+    ) -> Self {
+        let mut bounds = vec![];
+
+        for bound in param_env.caller_bounds() {
+            if let Some(mut type_outlives) = bound.as_type_outlives_clause() {
+                if infcx.next_trait_solver() {
+                    match crate::solve::deeply_normalize::<_, ScrubbedTraitError<'tcx>>(
+                        infcx.at(&ObligationCause::dummy(), param_env),
+                        type_outlives,
+                    ) {
+                        Ok(new) => type_outlives = new,
+                        Err(_) => {
+                            infcx.dcx().delayed_bug(format!("could not normalize `{bound}`"));
+                        }
+                    }
+                }
+                bounds.push(type_outlives);
+            }
+        }
+
+        // FIXME: This needs to be modified so that we normalize the known type
+        // outlives obligations then elaborate them into their region/type components.
+        // Otherwise, `<W<'a> as Mirror>::Assoc: 'b` will not imply `'a: 'b` even
+        // if we can normalize `'a`.
+        OutlivesEnvironment::from_normalized_bounds(
+            param_env,
+            bounds,
+            infcx.implied_bounds_tys_with_compat(
+                body_id,
+                param_env,
+                assumed_wf_tys,
+                implied_bounds_compat,
+            ),
+        )
+    }
+}
 
 #[extension(pub trait InferCtxtRegionExt<'tcx>)]
 impl<'tcx> InferCtxt<'tcx> {
@@ -15,10 +78,25 @@ impl<'tcx> InferCtxt<'tcx> {
     /// Prefer this method over `resolve_regions_with_normalize`, unless you are
     /// doing something specific for normalization.
     fn resolve_regions(
+        &self,
+        body_id: LocalDefId,
+        param_env: ty::ParamEnv<'tcx>,
+        assumed_wf_tys: impl IntoIterator<Item = Ty<'tcx>>,
+    ) -> Vec<RegionResolutionError<'tcx>> {
+        self.resolve_regions_with_outlives_env(&OutlivesEnvironment::new(
+            self,
+            body_id,
+            param_env,
+            assumed_wf_tys,
+        ))
+    }
+
+    /// Don't call this directly unless you know what you're doing.
+    fn resolve_regions_with_outlives_env(
         &self,
         outlives_env: &OutlivesEnvironment<'tcx>,
     ) -> Vec<RegionResolutionError<'tcx>> {
-        self.resolve_regions_with_normalize(outlives_env, |ty, origin| {
+        self.resolve_regions_with_normalize(&outlives_env, |ty, origin| {
             let ty = self.resolve_vars_if_possible(ty);
 
             if self.next_trait_solver() {

compiler/rustc_trait_selection/src/traits/auto_trait.rs

@@ -6,6 +6,7 @@ use std::iter;
 
 use rustc_data_structures::fx::{FxIndexMap, FxIndexSet, IndexEntry};
 use rustc_data_structures::unord::UnordSet;
+use rustc_hir::def_id::CRATE_DEF_ID;
 use rustc_infer::infer::DefineOpaqueTypes;
 use rustc_middle::ty::{Region, RegionVid};
 use tracing::debug;
@@ -13,6 +14,7 @@ use tracing::debug;
 use super::*;
 use crate::errors::UnableToConstructConstantValue;
 use crate::infer::region_constraints::{Constraint, RegionConstraintData};
+use crate::regions::OutlivesEnvironmentBuildExt;
 use crate::traits::project::ProjectAndUnifyResult;
 
 // FIXME(twk): this is obviously not nice to duplicate like that
@@ -158,7 +160,7 @@ impl<'tcx> AutoTraitFinder<'tcx> {
             panic!("Unable to fulfill trait {trait_did:?} for '{ty:?}': {errors:?}");
         }
 
-        let outlives_env = OutlivesEnvironment::new(full_env);
+        let outlives_env = OutlivesEnvironment::new(&infcx, CRATE_DEF_ID, full_env, []);
         let _ = infcx.process_registered_region_obligations(&outlives_env, |ty, _| Ok(ty));
 
         let region_data = infcx.inner.borrow_mut().unwrap_region_constraints().data().clone();

compiler/rustc_trait_selection/src/traits/coherence.rs

@@ -9,7 +9,7 @@ use std::fmt::Debug;
 use rustc_data_structures::fx::{FxHashSet, FxIndexSet};
 use rustc_errors::{Diag, EmissionGuarantee};
 use rustc_hir::def::DefKind;
-use rustc_hir::def_id::DefId;
+use rustc_hir::def_id::{CRATE_DEF_ID, DefId};
 use rustc_infer::infer::{DefineOpaqueTypes, InferCtxt, TyCtxtInferExt};
 use rustc_infer::traits::PredicateObligations;
 use rustc_middle::bug;
@@ -27,7 +27,6 @@ use tracing::{debug, instrument, warn};
 use super::ObligationCtxt;
 use crate::error_reporting::traits::suggest_new_overflow_limit;
 use crate::infer::InferOk;
-use crate::infer::outlives::env::OutlivesEnvironment;
 use crate::solve::inspect::{InspectGoal, ProofTreeInferCtxtExt, ProofTreeVisitor};
 use crate::solve::{SolverDelegate, deeply_normalize_for_diagnostics, inspect};
 use crate::traits::query::evaluate_obligation::InferCtxtExt;
@@ -596,8 +595,7 @@ fn try_prove_negated_where_clause<'tcx>(
     // FIXME: We could use the assumed_wf_types from both impls, I think,
     // if that wasn't implemented just for LocalDefId, and we'd need to do
     // the normalization ourselves since this is totally fallible...
-    let outlives_env = OutlivesEnvironment::new(param_env);
+    let errors = ocx.resolve_regions(CRATE_DEF_ID, param_env, []);
-    let errors = ocx.resolve_regions(&outlives_env);
     if !errors.is_empty() {
         return false;
     }

compiler/rustc_trait_selection/src/traits/engine.rs

@@ -8,7 +8,6 @@ use rustc_infer::infer::at::ToTrace;
 use rustc_infer::infer::canonical::{
     Canonical, CanonicalQueryResponse, CanonicalVarValues, QueryResponse,
 };
-use rustc_infer::infer::outlives::env::OutlivesEnvironment;
 use rustc_infer::infer::{DefineOpaqueTypes, InferCtxt, InferOk, RegionResolutionError, TypeTrace};
 use rustc_infer::traits::PredicateObligations;
 use rustc_macros::extension;
@@ -217,14 +216,15 @@ where
     /// will result in region constraints getting ignored.
     pub fn resolve_regions_and_report_errors(
         self,
-        generic_param_scope: LocalDefId,
+        body_id: LocalDefId,
-        outlives_env: &OutlivesEnvironment<'tcx>,
+        param_env: ty::ParamEnv<'tcx>,
+        assumed_wf_tys: impl IntoIterator<Item = Ty<'tcx>>,
     ) -> Result<(), ErrorGuaranteed> {
-        let errors = self.infcx.resolve_regions(outlives_env);
+        let errors = self.infcx.resolve_regions(body_id, param_env, assumed_wf_tys);
         if errors.is_empty() {
             Ok(())
         } else {
-            Err(self.infcx.err_ctxt().report_region_errors(generic_param_scope, &errors))
+            Err(self.infcx.err_ctxt().report_region_errors(body_id, &errors))
         }
     }
 
@@ -235,9 +235,11 @@ where
     #[must_use]
     pub fn resolve_regions(
         self,
-        outlives_env: &OutlivesEnvironment<'tcx>,
+        body_id: LocalDefId,
+        param_env: ty::ParamEnv<'tcx>,
+        assumed_wf_tys: impl IntoIterator<Item = Ty<'tcx>>,
     ) -> Vec<RegionResolutionError<'tcx>> {
-        self.infcx.resolve_regions(outlives_env)
+        self.infcx.resolve_regions(body_id, param_env, assumed_wf_tys)
     }
 }
 

compiler/rustc_trait_selection/src/traits/misc.rs

@@ -4,13 +4,10 @@ use std::assert_matches::assert_matches;
 
 use hir::LangItem;
 use rustc_ast::Mutability;
-use rustc_data_structures::fx::FxIndexSet;
 use rustc_hir as hir;
-use rustc_infer::infer::outlives::env::OutlivesEnvironment;
 use rustc_infer::infer::{RegionResolutionError, TyCtxtInferExt};
 use rustc_middle::ty::{self, AdtDef, Ty, TyCtxt, TypeVisitableExt, TypingMode};
 
-use super::outlives_bounds::InferCtxtExt;
 use crate::regions::InferCtxtRegionExt;
 use crate::traits::{self, FulfillmentError, ObligationCause};
 
@@ -170,15 +167,7 @@ pub fn type_allowed_to_implement_const_param_ty<'tcx>(
         }
 
         // Check regions assuming the self type of the impl is WF
-        let outlives_env = OutlivesEnvironment::with_bounds(
+        let errors = infcx.resolve_regions(parent_cause.body_id, param_env, [self_type]);
-            param_env,
-            infcx.implied_bounds_tys(
-                param_env,
-                parent_cause.body_id,
-                &FxIndexSet::from_iter([self_type]),
-            ),
-        );
-        let errors = infcx.resolve_regions(&outlives_env);
         if !errors.is_empty() {
             infringing_inner_tys.push((inner_ty, InfringingFieldsReason::Regions(errors)));
             continue;
@@ -261,15 +250,7 @@ pub fn all_fields_implement_trait<'tcx>(
             }
 
             // Check regions assuming the self type of the impl is WF
-            let outlives_env = OutlivesEnvironment::with_bounds(
+            let errors = infcx.resolve_regions(parent_cause.body_id, param_env, [self_type]);
-                param_env,
-                infcx.implied_bounds_tys(
-                    param_env,
-                    parent_cause.body_id,
-                    &FxIndexSet::from_iter([self_type]),
-                ),
-            );
-            let errors = infcx.resolve_regions(&outlives_env);
             if !errors.is_empty() {
                 infringing.push((field, ty, InfringingFieldsReason::Regions(errors)));
             }

compiler/rustc_trait_selection/src/traits/mod.rs

@@ -290,12 +290,10 @@ fn do_normalize_predicates<'tcx>(
 
     // We can use the `elaborated_env` here; the region code only
     // cares about declarations like `'a: 'b`.
-    let outlives_env = OutlivesEnvironment::new(elaborated_env);
-
     // FIXME: It's very weird that we ignore region obligations but apparently
     // still need to use `resolve_regions` as we need the resolved regions in
     // the normalized predicates.
-    let errors = infcx.resolve_regions(&outlives_env);
+    let errors = infcx.resolve_regions(cause.body_id, elaborated_env, []);
     if !errors.is_empty() {
         tcx.dcx().span_delayed_bug(
             span,

compiler/rustc_trait_selection/src/traits/outlives_bounds.rs

@@ -1,4 +1,3 @@
-use rustc_data_structures::fx::FxIndexSet;
 use rustc_infer::infer::InferOk;
 use rustc_infer::infer::resolve::OpportunisticRegionResolver;
 use rustc_infer::traits::query::type_op::ImpliedOutlivesBounds;
@@ -12,9 +11,6 @@ use tracing::instrument;
 use crate::infer::InferCtxt;
 use crate::traits::{ObligationCause, ObligationCtxt};
 
-pub type BoundsCompat<'a, 'tcx: 'a> = impl Iterator<Item = OutlivesBound<'tcx>> + 'a;
-pub type Bounds<'a, 'tcx: 'a> = impl Iterator<Item = OutlivesBound<'tcx>> + 'a;
-
 /// Implied bounds are region relationships that we deduce
 /// automatically. The idea is that (e.g.) a caller must check that a
 /// function's argument types are well-formed immediately before
@@ -110,36 +106,18 @@ fn implied_outlives_bounds<'a, 'tcx>(
     bounds
 }
 
-#[extension(pub trait InferCtxtExt<'a, 'tcx>)]
+#[extension(pub trait InferCtxtExt<'tcx>)]
-impl<'a, 'tcx: 'a> InferCtxt<'tcx> {
+impl<'tcx> InferCtxt<'tcx> {
-    /// Do *NOT* call this directly.
+    /// Do *NOT* call this directly. You probably want to construct a `OutlivesEnvironment`
-    fn implied_bounds_tys_compat(
+    /// instead if you're interested in the implied bounds for a given signature.
-        &'a self,
+    fn implied_bounds_tys_with_compat<Tys: IntoIterator<Item = Ty<'tcx>>>(
-        param_env: ParamEnv<'tcx>,
+        &self,
         body_id: LocalDefId,
-        tys: &'a FxIndexSet<Ty<'tcx>>,
+        param_env: ParamEnv<'tcx>,
+        tys: Tys,
         compat: bool,
-    ) -> BoundsCompat<'a, 'tcx> {
+    ) -> impl Iterator<Item = OutlivesBound<'tcx>> {
-        tys.iter()
+        tys.into_iter()
-            .flat_map(move |ty| implied_outlives_bounds(self, param_env, body_id, *ty, compat))
+            .flat_map(move |ty| implied_outlives_bounds(self, param_env, body_id, ty, compat))
-    }
-
-    /// If `-Z no-implied-bounds-compat` is set, calls `implied_bounds_tys_compat`
-    /// with `compat` set to `true`, otherwise `false`.
-    fn implied_bounds_tys(
-        &'a self,
-        param_env: ParamEnv<'tcx>,
-        body_id: LocalDefId,
-        tys: &'a FxIndexSet<Ty<'tcx>>,
-    ) -> Bounds<'a, 'tcx> {
-        tys.iter().flat_map(move |ty| {
-            implied_outlives_bounds(
-                self,
-                param_env,
-                body_id,
-                *ty,
-                !self.tcx.sess.opts.unstable_opts.no_implied_bounds_compat,
-            )
-        })
     }
 }

src/doc/rustc-dev-guide/src/traits/implied-bounds.md

@@ -40,7 +40,7 @@ requirements of impls and functions as explicit predicates.
 ### using implicit implied bounds as assumptions
 
 These bounds are not added to the `ParamEnv` of the affected item itself. For lexical
-region resolution they are added using [`fn OutlivesEnvironment::with_bounds`].
+region resolution they are added using [`fn OutlivesEnvironment::new`].
 Similarly, during MIR borrowck we add them using
 [`fn UniversalRegionRelationsBuilder::add_implied_bounds`].
 
@@ -55,7 +55,7 @@ The assumed outlives constraints for implicit bounds are computed using the
 MIR borrowck adds the outlives constraints for both the normalized and unnormalized types,
 lexical region resolution [only uses the unnormalized types][notnorm].
 
-[`fn OutlivesEnvironment::with_bounds`]: https://github.com/rust-lang/rust/blob/5b8bc568d28b2e922290c9a966b3231d0ce9398b/compiler/rustc_infer/src/infer/outlives/env.rs#L90-L97
+[`fn OutlivesEnvironment::new`]: TODO
 [`fn UniversalRegionRelationsBuilder::add_implied_bounds`]: https://github.com/rust-lang/rust/blob/5b8bc568d28b2e922290c9a966b3231d0ce9398b/compiler/rustc_borrowck/src/type_check/free_region_relations.rs#L316
 [mir]: https://github.com/rust-lang/rust/blob/91cae1dcdcf1a31bd8a92e4a63793d65cfe289bb/compiler/rustc_borrowck/src/type_check/free_region_relations.rs#L258-L332
 [`fn assumed_wf_types`]: https://github.com/rust-lang/rust/blob/5b8bc568d28b2e922290c9a966b3231d0ce9398b/compiler/rustc_ty_utils/src/implied_bounds.rs#L21