Auto merge of #98584 - lcnr:region-stuff-more-beans, r=oli-obk

continue nll transition by removing stuff

r? `@jackh726` for now

building on #98641

compiler/rustc_infer/src/infer/canonical/query_response.rs

@@ -128,7 +128,7 @@ fn make_query_response<T>(
         let region_constraints = self.with_region_constraints(|region_constraints| {
             make_query_region_constraints(
                 tcx,
-                region_obligations.iter().map(|(_, r_o)| (r_o.sup_type, r_o.sub_region)),
+                region_obligations.iter().map(|r_o| (r_o.sup_type, r_o.sub_region)),
                 region_constraints,
             )
         });

compiler/rustc_infer/src/infer/free_regions.rs

@@ -4,7 +4,6 @@
 //! and use that to decide when one free region outlives another, and so forth.
 
 use rustc_data_structures::transitive_relation::TransitiveRelation;
-use rustc_hir::def_id::DefId;
 use rustc_middle::ty::{self, Lift, Region, TyCtxt};
 
 /// Combines a `FreeRegionMap` and a `TyCtxt`.
@@ -14,16 +13,13 @@
 pub(crate) struct RegionRelations<'a, 'tcx> {
     pub tcx: TyCtxt<'tcx>,
 
-    /// The context used for debug messages
-    pub context: DefId,
-
     /// Free-region relationships.
     pub free_regions: &'a FreeRegionMap<'tcx>,
 }
 
 impl<'a, 'tcx> RegionRelations<'a, 'tcx> {
-    pub fn new(tcx: TyCtxt<'tcx>, context: DefId, free_regions: &'a FreeRegionMap<'tcx>) -> Self {
-        Self { tcx, context, free_regions }
+    pub fn new(tcx: TyCtxt<'tcx>, free_regions: &'a FreeRegionMap<'tcx>) -> Self {
+        Self { tcx, free_regions }
     }
 
     pub fn lub_free_regions(&self, r_a: Region<'tcx>, r_b: Region<'tcx>) -> Region<'tcx> {

compiler/rustc_infer/src/infer/lexical_region_resolve/mod.rs

@@ -120,13 +120,9 @@ fn infer_variable_values(
     ) -> LexicalRegionResolutions<'tcx> {
         let mut var_data = self.construct_var_data(self.tcx());
 
-        // Dorky hack to cause `dump_constraints` to only get called
-        // if debug mode is enabled:
-        debug!(
-            "----() End constraint listing (context={:?}) {:?}---",
-            self.region_rels.context,
-            self.dump_constraints(self.region_rels)
-        );
+        if cfg!(debug_assertions) {
+            self.dump_constraints();
+        }
 
         let graph = self.construct_graph();
         self.expand_givens(&graph);
@@ -156,8 +152,8 @@ fn construct_var_data(&self, tcx: TyCtxt<'tcx>) -> LexicalRegionResolutions<'tcx
         }
     }
 
-    fn dump_constraints(&self, free_regions: &RegionRelations<'_, 'tcx>) {
-        debug!("----() Start constraint listing (context={:?}) ()----", free_regions.context);
+    #[instrument(level = "debug", skip(self))]
+    fn dump_constraints(&self) {
         for (idx, (constraint, _)) in self.data.constraints.iter().enumerate() {
             debug!("Constraint {} => {:?}", idx, constraint);
         }

compiler/rustc_infer/src/infer/mod.rs

@@ -15,7 +15,6 @@
 use rustc_data_structures::undo_log::Rollback;
 use rustc_data_structures::unify as ut;
 use rustc_errors::{DiagnosticBuilder, ErrorGuaranteed};
-use rustc_hir as hir;
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_middle::infer::canonical::{Canonical, CanonicalVarValues};
 use rustc_middle::infer::unify_key::{ConstVarValue, ConstVariableValue};
@@ -147,7 +146,7 @@ pub struct InferCtxtInner<'tcx> {
     /// for each body-id in this map, which will process the
     /// obligations within. This is expected to be done 'late enough'
     /// that all type inference variables have been bound and so forth.
-    region_obligations: Vec<(hir::HirId, RegionObligation<'tcx>)>,
+    region_obligations: Vec<RegionObligation<'tcx>>,
 
     undo_log: InferCtxtUndoLogs<'tcx>,
 
@@ -171,7 +170,7 @@ fn new() -> InferCtxtInner<'tcx> {
     }
 
     #[inline]
-    pub fn region_obligations(&self) -> &[(hir::HirId, RegionObligation<'tcx>)] {
+    pub fn region_obligations(&self) -> &[RegionObligation<'tcx>] {
         &self.region_obligations
     }
 
@@ -1267,7 +1266,6 @@ pub fn skip_region_resolution(&self) {
     /// `resolve_vars_if_possible` as well as `fully_resolve`.
     pub fn resolve_regions(
         &self,
-        region_context: DefId,
         outlives_env: &OutlivesEnvironment<'tcx>,
     ) -> Vec<RegionResolutionError<'tcx>> {
         let (var_infos, data) = {
@@ -1286,8 +1284,7 @@ pub fn resolve_regions(
                 .into_infos_and_data()
         };
 
-        let region_rels =
-            &RegionRelations::new(self.tcx, region_context, outlives_env.free_region_map());
+        let region_rels = &RegionRelations::new(self.tcx, outlives_env.free_region_map());
 
         let (lexical_region_resolutions, errors) =
             lexical_region_resolve::resolve(outlives_env.param_env, region_rels, var_infos, data);
@@ -1302,12 +1299,8 @@ pub fn resolve_regions(
     /// result. After this, no more unification operations should be
     /// done -- or the compiler will panic -- but it is legal to use
     /// `resolve_vars_if_possible` as well as `fully_resolve`.
-    pub fn resolve_regions_and_report_errors(
-        &self,
-        region_context: DefId,
-        outlives_env: &OutlivesEnvironment<'tcx>,
-    ) {
-        let errors = self.resolve_regions(region_context, outlives_env);
+    pub fn resolve_regions_and_report_errors(&self, outlives_env: &OutlivesEnvironment<'tcx>) {
+        let errors = self.resolve_regions(outlives_env);
 
         if !self.is_tainted_by_errors() {
             // As a heuristic, just skip reporting region errors

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

 use crate::infer::free_regions::FreeRegionMap;
 use crate::infer::{GenericKind, InferCtxt};
 use crate::traits::query::OutlivesBound;
-use rustc_data_structures::fx::FxHashMap;
-use rustc_hir as hir;
 use rustc_middle::ty::{self, ReEarlyBound, ReFree, ReVar, Region};
 
 use super::explicit_outlives_bounds;
@@ -31,9 +29,7 @@ pub struct OutlivesEnvironment<'tcx> {
     pub param_env: ty::ParamEnv<'tcx>,
     free_region_map: FreeRegionMap<'tcx>,
 
-    // Contains, for each body B that we are checking (that is, the fn
-    // item, but also any nested closures), the set of implied region
-    // bounds that are in scope in that particular body.
+    // Contains the implied region bounds in scope for our current body.
     //
     // Example:
     //
@@ -43,24 +39,15 @@ pub struct OutlivesEnvironment<'tcx> {
     // } // body B0
     // ```
     //
-    // Here, for body B0, the list would be `[T: 'a]`, because we
+    // 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, the list would be `[T: 'a, T: 'b]`, because we
+    // 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.
-    //
-    // We collect this map as we descend the tree. We then use the
-    // results when proving outlives obligations like `T: 'x` later
-    // (e.g., if `T: 'x` must be proven within the body B1, then we
-    // know it is true if either `'a: 'x` or `'b: 'x`).
-    region_bound_pairs_map: FxHashMap<hir::HirId, RegionBoundPairs<'tcx>>,
-
-    // Used to compute `region_bound_pairs_map`: contains the set of
-    // in-scope region-bound pairs thus far.
-    region_bound_pairs_accum: RegionBoundPairs<'tcx>,
+    region_bound_pairs: RegionBoundPairs<'tcx>,
 }
 
 /// "Region-bound pairs" tracks outlives relations that are known to
@@ -73,8 +60,7 @@ pub fn new(param_env: ty::ParamEnv<'tcx>) -> Self {
         let mut env = OutlivesEnvironment {
             param_env,
             free_region_map: Default::default(),
-            region_bound_pairs_map: Default::default(),
-            region_bound_pairs_accum: vec![],
+            region_bound_pairs: Default::default(),
         };
 
         env.add_outlives_bounds(None, explicit_outlives_bounds(param_env));
@@ -87,62 +73,9 @@ pub fn free_region_map(&self) -> &FreeRegionMap<'tcx> {
         &self.free_region_map
     }
 
-    /// Borrows current value of the `region_bound_pairs`.
-    pub fn region_bound_pairs_map(&self) -> &FxHashMap<hir::HirId, RegionBoundPairs<'tcx>> {
-        &self.region_bound_pairs_map
-    }
-
-    /// This is a hack to support the old-school regionck, which
-    /// processes region constraints from the main function and the
-    /// closure together. In that context, when we enter a closure, we
-    /// want to be able to "save" the state of the surrounding a
-    /// function. We can then add implied bounds and the like from the
-    /// closure arguments into the environment -- these should only
-    /// apply in the closure body, so once we exit, we invoke
-    /// `pop_snapshot_post_typeck_child` to remove them.
-    ///
-    /// Example:
-    ///
-    /// ```ignore (pseudo-rust)
-    /// fn foo<T>() {
-    ///    callback(for<'a> |x: &'a T| {
-    ///         // ^^^^^^^ not legal syntax, but probably should be
-    ///         // within this closure body, `T: 'a` holds
-    ///    })
-    /// }
-    /// ```
-    ///
-    /// This "containment" of closure's effects only works so well. In
-    /// particular, we (intentionally) leak relationships between free
-    /// regions that are created by the closure's bounds. The case
-    /// where this is useful is when you have (e.g.) a closure with a
-    /// signature like `for<'a, 'b> fn(x: &'a &'b u32)` -- in this
-    /// case, we want to keep the relationship `'b: 'a` in the
-    /// free-region-map, so that later if we have to take `LUB('b,
-    /// 'a)` we can get the result `'b`.
-    ///
-    /// I have opted to keep **all modifications** to the
-    /// free-region-map, however, and not just those that concern free
-    /// variables bound in the closure. The latter seems more correct,
-    /// but it is not the existing behavior, and I could not find a
-    /// case where the existing behavior went wrong. In any case, it
-    /// seems like it'd be readily fixed if we wanted. There are
-    /// similar leaks around givens that seem equally suspicious, to
-    /// be honest. --nmatsakis
-    pub fn push_snapshot_pre_typeck_child(&self) -> usize {
-        self.region_bound_pairs_accum.len()
-    }
-
-    /// See `push_snapshot_pre_typeck_child`.
-    pub fn pop_snapshot_post_typeck_child(&mut self, len: usize) {
-        self.region_bound_pairs_accum.truncate(len);
-    }
-
-    /// Save the current set of region-bound pairs under the given `body_id`.
-    pub fn save_implied_bounds(&mut self, body_id: hir::HirId) {
-        let old =
-            self.region_bound_pairs_map.insert(body_id, self.region_bound_pairs_accum.clone());
-        assert!(old.is_none());
+    /// Borrows current `region_bound_pairs`.
+    pub fn region_bound_pairs(&self) -> &RegionBoundPairs<'tcx> {
+        &self.region_bound_pairs
     }
 
     /// Processes outlives bounds that are known to hold, whether from implied or other sources.
@@ -164,11 +97,10 @@ pub fn add_outlives_bounds<I>(
             debug!("add_outlives_bounds: outlives_bound={:?}", outlives_bound);
             match outlives_bound {
                 OutlivesBound::RegionSubParam(r_a, param_b) => {
-                    self.region_bound_pairs_accum.push((r_a, GenericKind::Param(param_b)));
+                    self.region_bound_pairs.push((r_a, GenericKind::Param(param_b)));
                 }
                 OutlivesBound::RegionSubProjection(r_a, projection_b) => {
-                    self.region_bound_pairs_accum
-                        .push((r_a, GenericKind::Projection(projection_b)));
+                    self.region_bound_pairs.push((r_a, GenericKind::Projection(projection_b)));
                 }
                 OutlivesBound::RegionSubRegion(r_a, r_b) => {
                     if let (ReEarlyBound(_) | ReFree(_), ReVar(vid_b)) = (r_a.kind(), r_b.kind()) {

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

@@ -60,18 +60,16 @@
 //! imply that `'b: 'a`.
 
 use crate::infer::outlives::components::{push_outlives_components, Component};
+use crate::infer::outlives::env::OutlivesEnvironment;
 use crate::infer::outlives::env::RegionBoundPairs;
 use crate::infer::outlives::verify::VerifyBoundCx;
 use crate::infer::{
     self, GenericKind, InferCtxt, RegionObligation, SubregionOrigin, UndoLog, VerifyBound,
 };
 use crate::traits::{ObligationCause, ObligationCauseCode};
+use rustc_data_structures::undo_log::UndoLogs;
 use rustc_middle::ty::subst::GenericArgKind;
 use rustc_middle::ty::{self, Region, Ty, TyCtxt, TypeFoldable};
-
-use rustc_data_structures::fx::FxHashMap;
-use rustc_data_structures::undo_log::UndoLogs;
-use rustc_hir as hir;
 use smallvec::smallvec;
 
 impl<'cx, 'tcx> InferCtxt<'cx, 'tcx> {
@@ -80,16 +78,11 @@ impl<'cx, 'tcx> InferCtxt<'cx, 'tcx> {
     /// and later processed by regionck, when full type information is
     /// available (see `region_obligations` field for more
     /// information).
-    pub fn register_region_obligation(
-        &self,
-        body_id: hir::HirId,
-        obligation: RegionObligation<'tcx>,
-    ) {
-        debug!("register_region_obligation(body_id={:?}, obligation={:?})", body_id, obligation);
-
+    #[instrument(level = "debug", skip(self))]
+    pub fn register_region_obligation(&self, obligation: RegionObligation<'tcx>) {
         let mut inner = self.inner.borrow_mut();
         inner.undo_log.push(UndoLog::PushRegionObligation);
-        inner.region_obligations.push((body_id, obligation));
+        inner.region_obligations.push(obligation);
     }
 
     pub fn register_region_obligation_with_cause(
@@ -109,14 +102,11 @@ pub fn register_region_obligation_with_cause(
             )
         });
 
-        self.register_region_obligation(
-            cause.body_id,
-            RegionObligation { sup_type, sub_region, origin },
-        );
+        self.register_region_obligation(RegionObligation { sup_type, sub_region, origin });
     }
 
     /// Trait queries just want to pass back type obligations "as is"
-    pub fn take_registered_region_obligations(&self) -> Vec<(hir::HirId, RegionObligation<'tcx>)> {
+    pub fn take_registered_region_obligations(&self) -> Vec<RegionObligation<'tcx>> {
         std::mem::take(&mut self.inner.borrow_mut().region_obligations)
     }
 
@@ -144,10 +134,10 @@ pub fn take_registered_region_obligations(&self) -> Vec<(hir::HirId, RegionOblig
     /// - `param_env` is the parameter environment for the enclosing function.
     /// - `body_id` is the body-id whose region obligations are being
     ///   processed.
-    #[instrument(level = "debug", skip(self, region_bound_pairs_map))]
+    #[instrument(level = "debug", skip(self, region_bound_pairs))]
     pub fn process_registered_region_obligations(
         &self,
-        region_bound_pairs_map: &FxHashMap<hir::HirId, RegionBoundPairs<'tcx>>,
+        region_bound_pairs: &RegionBoundPairs<'tcx>,
         param_env: ty::ParamEnv<'tcx>,
     ) {
         assert!(
@@ -157,7 +147,7 @@ pub fn process_registered_region_obligations(
 
         let my_region_obligations = self.take_registered_region_obligations();
 
-        for (body_id, RegionObligation { sup_type, sub_region, origin }) in my_region_obligations {
+        for RegionObligation { sup_type, sub_region, origin } in my_region_obligations {
             debug!(
                 "process_registered_region_obligations: sup_type={:?} sub_region={:?} origin={:?}",
                 sup_type, sub_region, origin
@@ -165,18 +155,23 @@ pub fn process_registered_region_obligations(
 
             let sup_type = self.resolve_vars_if_possible(sup_type);
 
-            if let Some(region_bound_pairs) = region_bound_pairs_map.get(&body_id) {
-                let outlives =
-                    &mut TypeOutlives::new(self, self.tcx, &region_bound_pairs, None, param_env);
-                outlives.type_must_outlive(origin, sup_type, sub_region);
-            } else {
-                self.tcx.sess.delay_span_bug(
-                    origin.span(),
-                    &format!("no region-bound-pairs for {:?}", body_id),
-                );
-            }
+            let outlives =
+                &mut TypeOutlives::new(self, self.tcx, &region_bound_pairs, None, param_env);
+            outlives.type_must_outlive(origin, sup_type, sub_region);
         }
     }
+
+    pub fn check_region_obligations_and_report_errors(
+        &self,
+        outlives_env: &OutlivesEnvironment<'tcx>,
+    ) {
+        self.process_registered_region_obligations(
+            outlives_env.region_bound_pairs(),
+            outlives_env.param_env,
+        );
+
+        self.resolve_regions_and_report_errors(outlives_env)
+    }
 }
 
 /// The `TypeOutlives` struct has the job of "lowering" a `T: 'a`

compiler/rustc_trait_selection/src/traits/auto_trait.rs

@@ -212,15 +212,7 @@ pub fn find_auto_trait_generics<A>(
                 panic!("Unable to fulfill trait {:?} for '{:?}': {:?}", trait_did, ty, errors);
             }
 
-            let body_id_map: FxHashMap<_, _> = infcx
-                .inner
-                .borrow()
-                .region_obligations()
-                .iter()
-                .map(|&(id, _)| (id, vec![]))
-                .collect();
-
-            infcx.process_registered_region_obligations(&body_id_map, full_env);
+            infcx.process_registered_region_obligations(&Default::default(), full_env);
 
             let region_data = infcx
                 .inner

compiler/rustc_trait_selection/src/traits/coherence.rs

@@ -16,7 +16,6 @@
 //use rustc_data_structures::fx::FxHashMap;
 use rustc_errors::Diagnostic;
 use rustc_hir::def_id::{DefId, LOCAL_CRATE};
-use rustc_hir::CRATE_HIR_ID;
 use rustc_infer::infer::{InferCtxt, TyCtxtInferExt};
 use rustc_infer::traits::{util, TraitEngine};
 use rustc_middle::traits::specialization_graph::OverlapMode;
@@ -317,14 +316,13 @@ fn negative_impl<'cx, 'tcx>(
         let (subject2, obligations) =
             impl_subject_and_oblig(selcx, impl_env, impl2_def_id, impl2_substs);
 
-        !equate(&infcx, impl_env, impl1_def_id, subject1, subject2, obligations)
+        !equate(&infcx, impl_env, subject1, subject2, obligations)
     })
 }
 
 fn equate<'cx, 'tcx>(
     infcx: &InferCtxt<'cx, 'tcx>,
     impl_env: ty::ParamEnv<'tcx>,
-    impl1_def_id: DefId,
     subject1: ImplSubject<'tcx>,
     subject2: ImplSubject<'tcx>,
     obligations: impl Iterator<Item = PredicateObligation<'tcx>>,
@@ -341,7 +339,7 @@ fn equate<'cx, 'tcx>(
     let opt_failing_obligation = obligations
         .into_iter()
         .chain(more_obligations)
-        .find(|o| negative_impl_exists(selcx, impl_env, impl1_def_id, o));
+        .find(|o| negative_impl_exists(selcx, impl_env, o));
 
     if let Some(failing_obligation) = opt_failing_obligation {
         debug!("overlap: obligation unsatisfiable {:?}", failing_obligation);
@@ -356,18 +354,17 @@ fn equate<'cx, 'tcx>(
 fn negative_impl_exists<'cx, 'tcx>(
     selcx: &SelectionContext<'cx, 'tcx>,
     param_env: ty::ParamEnv<'tcx>,
-    region_context: DefId,
     o: &PredicateObligation<'tcx>,
 ) -> bool {
     let infcx = &selcx.infcx().fork();
 
-    if resolve_negative_obligation(infcx, param_env, region_context, o) {
+    if resolve_negative_obligation(infcx, param_env, o) {
         return true;
     }
 
     // Try to prove a negative obligation exists for super predicates
     for o in util::elaborate_predicates(infcx.tcx, iter::once(o.predicate)) {
-        if resolve_negative_obligation(infcx, param_env, region_context, &o) {
+        if resolve_negative_obligation(infcx, param_env, &o) {
             return true;
         }
     }
@@ -379,7 +376,6 @@ fn negative_impl_exists<'cx, 'tcx>(
 fn resolve_negative_obligation<'cx, 'tcx>(
     infcx: &InferCtxt<'cx, 'tcx>,
     param_env: ty::ParamEnv<'tcx>,
-    region_context: DefId,
     o: &PredicateObligation<'tcx>,
 ) -> bool {
     let tcx = infcx.tcx;
@@ -397,19 +393,11 @@ fn resolve_negative_obligation<'cx, 'tcx>(
         return false;
     }
 
-    let mut outlives_env = OutlivesEnvironment::new(param_env);
-    // FIXME -- add "assumed to be well formed" types into the `outlives_env`
-
-    // "Save" the accumulated implied bounds into the outlives environment
-    // (due to the FIXME above, there aren't any, but this step is still needed).
-    // The "body id" is given as `CRATE_HIR_ID`, which is the same body-id used
-    // by the "dummy" causes elsewhere (body-id is only relevant when checking
-    // function bodies with closures).
-    outlives_env.save_implied_bounds(CRATE_HIR_ID);
-
-    infcx.process_registered_region_obligations(outlives_env.region_bound_pairs_map(), param_env);
+    // FIXME -- also add "assumed to be well formed" types into the `outlives_env`
+    let outlives_env = OutlivesEnvironment::new(param_env);
+    infcx.process_registered_region_obligations(outlives_env.region_bound_pairs(), param_env);
 
-    let errors = infcx.resolve_regions(region_context, &outlives_env);
+    let errors = infcx.resolve_regions(&outlives_env);
 
     if !errors.is_empty() {
         return false;

compiler/rustc_trait_selection/src/traits/mod.rs

@@ -198,17 +198,13 @@ pub fn type_known_to_meet_bound_modulo_regions<'a, 'tcx>(
     }
 }
 
+#[instrument(level = "debug", skip(tcx, elaborated_env))]
 fn do_normalize_predicates<'tcx>(
     tcx: TyCtxt<'tcx>,
-    region_context: DefId,
     cause: ObligationCause<'tcx>,
     elaborated_env: ty::ParamEnv<'tcx>,
     predicates: Vec<ty::Predicate<'tcx>>,
 ) -> Result<Vec<ty::Predicate<'tcx>>, ErrorGuaranteed> {
-    debug!(
-        "do_normalize_predicates(predicates={:?}, region_context={:?}, cause={:?})",
-        predicates, region_context, cause,
-    );
     let span = cause.span;
     tcx.infer_ctxt().enter(|infcx| {
         // FIXME. We should really... do something with these region
@@ -240,7 +236,7 @@ fn do_normalize_predicates<'tcx>(
         // cares about declarations like `'a: 'b`.
         let outlives_env = OutlivesEnvironment::new(elaborated_env);
 
-        infcx.resolve_regions_and_report_errors(region_context, &outlives_env);
+        infcx.resolve_regions_and_report_errors(&outlives_env);
 
         let predicates = match infcx.fully_resolve(predicates) {
             Ok(predicates) => predicates,
@@ -269,9 +265,9 @@ fn do_normalize_predicates<'tcx>(
 
 // FIXME: this is gonna need to be removed ...
 /// Normalizes the parameter environment, reporting errors if they occur.
+#[instrument(level = "debug", skip(tcx))]
 pub fn normalize_param_env_or_error<'tcx>(
     tcx: TyCtxt<'tcx>,
-    region_context: DefId,
     unnormalized_env: ty::ParamEnv<'tcx>,
     cause: ObligationCause<'tcx>,
 ) -> ty::ParamEnv<'tcx> {
@@ -289,12 +285,6 @@ pub fn normalize_param_env_or_error<'tcx>(
     // parameter environments once for every fn as it goes,
     // and errors will get reported then; so outside of type inference we
     // can be sure that no errors should occur.
-
-    debug!(
-        "normalize_param_env_or_error(region_context={:?}, unnormalized_env={:?}, cause={:?})",
-        region_context, unnormalized_env, cause
-    );
-
     let mut predicates: Vec<_> =
         util::elaborate_predicates(tcx, unnormalized_env.caller_bounds().into_iter())
             .map(|obligation| obligation.predicate)
@@ -338,7 +328,6 @@ pub fn normalize_param_env_or_error<'tcx>(
     );
     let Ok(non_outlives_predicates) = do_normalize_predicates(
         tcx,
-        region_context,
         cause.clone(),
         elaborated_env,
         predicates,
@@ -362,7 +351,6 @@ pub fn normalize_param_env_or_error<'tcx>(
     );
     let Ok(outlives_predicates) = do_normalize_predicates(
         tcx,
-        region_context,
         cause,
         outlives_env,
         outlives_predicates,

compiler/rustc_trait_selection/src/traits/query/dropck_outlives.rs

-use crate::infer::at::At;
-use crate::infer::canonical::OriginalQueryValues;
-use crate::infer::InferOk;
-
-use rustc_middle::ty::subst::GenericArg;
 use rustc_middle::ty::{self, Ty, TyCtxt};
 
 pub use rustc_middle::traits::query::{DropckConstraint, DropckOutlivesResult};
 
-pub trait AtExt<'tcx> {
-    fn dropck_outlives(&self, ty: Ty<'tcx>) -> InferOk<'tcx, Vec<GenericArg<'tcx>>>;
-}
-
-impl<'cx, 'tcx> AtExt<'tcx> for At<'cx, 'tcx> {
-    /// Given a type `ty` of some value being dropped, computes a set
-    /// of "kinds" (types, regions) that must be outlive the execution
-    /// of the destructor. These basically correspond to data that the
-    /// destructor might access. This is used during regionck to
-    /// impose "outlives" constraints on any lifetimes referenced
-    /// within.
-    ///
-    /// The rules here are given by the "dropck" RFCs, notably [#1238]
-    /// and [#1327]. This is a fixed-point computation, where we
-    /// explore all the data that will be dropped (transitively) when
-    /// a value of type `ty` is dropped. For each type T that will be
-    /// dropped and which has a destructor, we must assume that all
-    /// the types/regions of T are live during the destructor, unless
-    /// they are marked with a special attribute (`#[may_dangle]`).
-    ///
-    /// [#1238]: https://github.com/rust-lang/rfcs/blob/master/text/1238-nonparametric-dropck.md
-    /// [#1327]: https://github.com/rust-lang/rfcs/blob/master/text/1327-dropck-param-eyepatch.md
-    fn dropck_outlives(&self, ty: Ty<'tcx>) -> InferOk<'tcx, Vec<GenericArg<'tcx>>> {
-        debug!("dropck_outlives(ty={:?}, param_env={:?})", ty, self.param_env,);
-
-        // Quick check: there are a number of cases that we know do not require
-        // any destructor.
-        let tcx = self.infcx.tcx;
-        if trivial_dropck_outlives(tcx, ty) {
-            return InferOk { value: vec![], obligations: vec![] };
-        }
-
-        let mut orig_values = OriginalQueryValues::default();
-        let c_ty = self.infcx.canonicalize_query(self.param_env.and(ty), &mut orig_values);
-        let span = self.cause.span;
-        debug!("c_ty = {:?}", c_ty);
-        if let Ok(result) = tcx.dropck_outlives(c_ty)
-            && result.is_proven()
-            && let Ok(InferOk { value, obligations }) =
-                self.infcx.instantiate_query_response_and_region_obligations(
-                    self.cause,
-                    self.param_env,
-                    &orig_values,
-                    result,
-                )
-        {
-            let ty = self.infcx.resolve_vars_if_possible(ty);
-            let kinds = value.into_kinds_reporting_overflows(tcx, span, ty);
-            return InferOk { value: kinds, obligations };
-        }
-
-        // Errors and ambiguity in dropck occur in two cases:
-        // - unresolved inference variables at the end of typeck
-        // - non well-formed types where projections cannot be resolved
-        // Either of these should have created an error before.
-        tcx.sess.delay_span_bug(span, "dtorck encountered internal error");
-
-        InferOk { value: vec![], obligations: vec![] }
-    }
-}
-
 /// This returns true if the type `ty` is "trivial" for
 /// dropck-outlives -- that is, if it doesn't require any types to
 /// outlive. This is similar but not *quite* the same as the
@@ -79,6 +13,8 @@ fn dropck_outlives(&self, ty: Ty<'tcx>) -> InferOk<'tcx, Vec<GenericArg<'tcx>>>
 ///
 /// Note also that `needs_drop` requires a "global" type (i.e., one
 /// with erased regions), but this function does not.
+///
+// FIXME(@lcnr): remove this module and move this function somewhere else.
 pub fn trivial_dropck_outlives<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> bool {
     match ty.kind() {
         // None of these types have a destructor and hence they do not
@@ -105,7 +41,7 @@ pub fn trivial_dropck_outlives<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> bool {
         ty::Array(ty, _) | ty::Slice(ty) => trivial_dropck_outlives(tcx, *ty),
 
         // (T1..Tn) and closures have same properties as T1..Tn --
-        // check if *any* of those are trivial.
+        // check if *all* of them are trivial.
         ty::Tuple(tys) => tys.iter().all(|t| trivial_dropck_outlives(tcx, t)),
         ty::Closure(_, ref substs) => {
             trivial_dropck_outlives(tcx, substs.as_closure().tupled_upvars_ty())

compiler/rustc_trait_selection/src/traits/query/type_op/custom.rs

@@ -95,7 +95,7 @@ pub fn scrape_region_constraints<'tcx, Op: super::TypeOp<'tcx, Output = R>, R>(
         infcx.tcx,
         region_obligations
             .iter()
-            .map(|(_, r_o)| (r_o.sup_type, r_o.sub_region))
+            .map(|r_o| (r_o.sup_type, r_o.sub_region))
             .map(|(ty, r)| (infcx.resolve_vars_if_possible(ty), r)),
         &region_constraint_data,
     );

compiler/rustc_ty_utils/src/ty.rs

@@ -211,7 +211,7 @@ fn param_env(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ParamEnv<'_> {
         tcx.hir().maybe_body_owned_by(id).map_or(id, |body| body.hir_id)
     });
     let cause = traits::ObligationCause::misc(tcx.def_span(def_id), body_id);
-    traits::normalize_param_env_or_error(tcx, def_id, unnormalized_env, cause)
+    traits::normalize_param_env_or_error(tcx, unnormalized_env, cause)
 }
 
 /// Elaborate the environment.

compiler/rustc_typeck/src/check/check.rs

@@ -13,6 +13,7 @@
 use rustc_hir::intravisit::Visitor;
 use rustc_hir::lang_items::LangItem;
 use rustc_hir::{ItemKind, Node, PathSegment};
+use rustc_infer::infer::outlives::env::OutlivesEnvironment;
 use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
 use rustc_infer::infer::{RegionVariableOrigin, TyCtxtInferExt};
 use rustc_infer::traits::Obligation;
@@ -736,10 +737,8 @@ fn check_opaque_meets_bounds<'tcx>(
             hir::OpaqueTyOrigin::FnReturn(..) | hir::OpaqueTyOrigin::AsyncFn(..) => {}
             // Can have different predicates to their defining use
             hir::OpaqueTyOrigin::TyAlias => {
-                // Finally, resolve all regions. This catches wily misuses of
-                // lifetime parameters.
-                let fcx = FnCtxt::new(&inh, param_env, hir_id);
-                fcx.regionck_item(hir_id, span, FxHashSet::default());
+                let outlives_environment = OutlivesEnvironment::new(param_env);
+                infcx.check_region_obligations_and_report_errors(&outlives_environment);
             }
         }
 

compiler/rustc_typeck/src/check/compare_method.rs

+use crate::check::regionck::OutlivesEnvironmentExt;
 use crate::errors::LifetimesOrBoundsMismatchOnTrait;
 use rustc_data_structures::stable_set::FxHashSet;
 use rustc_errors::{pluralize, struct_span_err, Applicability, DiagnosticId, ErrorGuaranteed};
@@ -5,6 +6,7 @@
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::intravisit;
 use rustc_hir::{GenericParamKind, ImplItemKind, TraitItemKind};
+use rustc_infer::infer::outlives::env::OutlivesEnvironment;
 use rustc_infer::infer::{self, InferOk, TyCtxtInferExt};
 use rustc_infer::traits::util;
 use rustc_middle::ty::error::{ExpectedFound, TypeError};
@@ -78,10 +80,11 @@ fn compare_predicate_entailment<'tcx>(
     let trait_to_impl_substs = impl_trait_ref.substs;
 
     // This node-id should be used for the `body_id` field on each
-    // `ObligationCause` (and the `FnCtxt`). This is what
-    // `regionck_item` expects.
+    // `ObligationCause` (and the `FnCtxt`).
+    //
+    // FIXME(@lcnr): remove that after removing `cause.body_id` from
+    // obligations.
     let impl_m_hir_id = tcx.hir().local_def_id_to_hir_id(impl_m.def_id.expect_local());
-
     // We sometimes modify the span further down.
     let mut cause = ObligationCause::new(
         impl_m_span,
@@ -208,8 +211,7 @@ fn compare_predicate_entailment<'tcx>(
         Reveal::UserFacing,
         hir::Constness::NotConst,
     );
-    let param_env =
-        traits::normalize_param_env_or_error(tcx, impl_m.def_id, param_env, normalize_cause);
+    let param_env = traits::normalize_param_env_or_error(tcx, param_env, normalize_cause);
 
     tcx.infer_ctxt().enter(|infcx| {
         let inh = Inherited::new(infcx, impl_m.def_id.expect_local());
@@ -399,8 +401,9 @@ fn compare_predicate_entailment<'tcx>(
 
         // Finally, resolve all regions. This catches wily misuses of
         // lifetime parameters.
-        let fcx = FnCtxt::new(&inh, param_env, impl_m_hir_id);
-        fcx.regionck_item(impl_m_hir_id, impl_m_span, wf_tys);
+        let mut outlives_environment = OutlivesEnvironment::new(param_env);
+        outlives_environment.add_implied_bounds(infcx, wf_tys, impl_m_hir_id);
+        infcx.check_region_obligations_and_report_errors(&outlives_environment);
 
         Ok(())
     })
@@ -1155,8 +1158,8 @@ pub(crate) fn compare_const_impl<'tcx>(
             return;
         }
 
-        let fcx = FnCtxt::new(&inh, param_env, impl_c_hir_id);
-        fcx.regionck_item(impl_c_hir_id, impl_c_span, FxHashSet::default());
+        let outlives_environment = OutlivesEnvironment::new(param_env);
+        infcx.resolve_regions_and_report_errors(&outlives_environment);
     });
 }
 
@@ -1247,12 +1250,7 @@ fn compare_type_predicate_entailment<'tcx>(
         Reveal::UserFacing,
         hir::Constness::NotConst,
     );
-    let param_env = traits::normalize_param_env_or_error(
-        tcx,
-        impl_ty.def_id,
-        param_env,
-        normalize_cause.clone(),
-    );
+    let param_env = traits::normalize_param_env_or_error(tcx, param_env, normalize_cause.clone());
     tcx.infer_ctxt().enter(|infcx| {
         let inh = Inherited::new(infcx, impl_ty.def_id.expect_local());
         let infcx = &inh.infcx;
@@ -1279,8 +1277,8 @@ fn compare_type_predicate_entailment<'tcx>(
 
         // Finally, resolve all regions. This catches wily misuses of
         // lifetime parameters.
-        let fcx = FnCtxt::new(&inh, param_env, impl_ty_hir_id);
-        fcx.regionck_item(impl_ty_hir_id, impl_ty_span, FxHashSet::default());
+        let outlives_environment = OutlivesEnvironment::new(param_env);
+        infcx.check_region_obligations_and_report_errors(&outlives_environment);
 
         Ok(())
     })
@@ -1504,12 +1502,16 @@ pub fn check_type_bounds<'tcx>(
 
         // Finally, resolve all regions. This catches wily misuses of
         // lifetime parameters.
+        //
+        // FIXME: Remove that `FnCtxt`.
         let fcx = FnCtxt::new(&inh, param_env, impl_ty_hir_id);
         let implied_bounds = match impl_ty.container {
             ty::TraitContainer(_) => FxHashSet::default(),
             ty::ImplContainer(def_id) => fcx.impl_implied_bounds(def_id, impl_ty_span),
         };
-        fcx.regionck_item(impl_ty_hir_id, impl_ty_span, implied_bounds);
+        let mut outlives_environment = OutlivesEnvironment::new(param_env);
+        outlives_environment.add_implied_bounds(infcx, implied_bounds, impl_ty_hir_id);
+        infcx.check_region_obligations_and_report_errors(&outlives_environment);
 
         Ok(())
     })

compiler/rustc_typeck/src/check/dropck.rs

-use crate::check::regionck::RegionCtxt;
-use crate::hir;
+// FIXME(@lcnr): Move this module out of `rustc_typeck`.
+//
+// We don't do any drop checking during hir typeck.
 use crate::hir::def_id::{DefId, LocalDefId};
 use rustc_errors::{struct_span_err, ErrorGuaranteed};
 use rustc_middle::ty::error::TypeError;
@@ -7,7 +8,6 @@
 use rustc_middle::ty::subst::SubstsRef;
 use rustc_middle::ty::util::IgnoreRegions;
 use rustc_middle::ty::{self, Predicate, Ty, TyCtxt};
-use rustc_span::Span;
 
 /// This function confirms that the `Drop` implementation identified by
 /// `drop_impl_did` is not any more specialized than the type it is
@@ -229,19 +229,6 @@ fn ensure_drop_predicates_are_implied_by_item_defn<'tcx>(
     result
 }
 
-/// This function is not only checking that the dropck obligations are met for
-/// the given type, but it's also currently preventing non-regular recursion in
-/// types from causing stack overflows (dropck_no_diverge_on_nonregular_*.rs).
-///
-/// FIXME: Completely rip out dropck and regionck.
-pub(crate) fn check_drop_obligations<'a, 'tcx>(
-    _rcx: &mut RegionCtxt<'a, 'tcx>,
-    _ty: Ty<'tcx>,
-    _span: Span,
-    _body_id: hir::HirId,
-) {
-}
-
 // This is an implementation of the TypeRelation trait with the
 // aim of simply comparing for equality (without side-effects).
 // It is not intended to be used anywhere else other than here.

compiler/rustc_typeck/src/check/mod.rs

@@ -368,7 +368,7 @@ fn typeck_with_fallback<'tcx>(
 
     let typeck_results = Inherited::build(tcx, def_id).enter(|inh| {
         let param_env = tcx.param_env(def_id);
-        let (fcx, wf_tys) = if let Some(hir::FnSig { header, decl, .. }) = fn_sig {
+        let fcx = if let Some(hir::FnSig { header, decl, .. }) = fn_sig {
             let fn_sig = if crate::collect::get_infer_ret_ty(&decl.output).is_some() {
                 let fcx = FnCtxt::new(&inh, param_env, body.value.hir_id);
                 <dyn AstConv<'_>>::ty_of_fn(&fcx, id, header.unsafety, header.abi, decl, None, None)
@@ -378,13 +378,7 @@ fn typeck_with_fallback<'tcx>(
 
             check_abi(tcx, id, span, fn_sig.abi());
 
-            // When normalizing the function signature, we assume all types are
-            // well-formed. So, we don't need to worry about the obligations
-            // from normalization. We could just discard these, but to align with
-            // compare_method and elsewhere, we just add implied bounds for
-            // these types.
-            let mut wf_tys = FxHashSet::default();
-            // Compute the fty from point of view of inside the fn.
+            // Compute the function signature from point of view of inside the fn.
             let fn_sig = tcx.liberate_late_bound_regions(def_id.to_def_id(), fn_sig);
             let fn_sig = inh.normalize_associated_types_in(
                 body.value.span,
@@ -392,10 +386,7 @@ fn typeck_with_fallback<'tcx>(
                 param_env,
                 fn_sig,
             );
-            wf_tys.extend(fn_sig.inputs_and_output.iter());
-
-            let fcx = check_fn(&inh, param_env, fn_sig, decl, id, body, None, true).0;
-            (fcx, wf_tys)
+            check_fn(&inh, param_env, fn_sig, decl, id, body, None, true).0
         } else {
             let fcx = FnCtxt::new(&inh, param_env, body.value.hir_id);
             let expected_type = body_ty
@@ -458,7 +449,7 @@ fn typeck_with_fallback<'tcx>(
 
             fcx.write_ty(id, expected_type);
 
-            (fcx, FxHashSet::default())
+            fcx
         };
 
         let fallback_has_occurred = fcx.type_inference_fallback();
@@ -490,11 +481,7 @@ fn typeck_with_fallback<'tcx>(
 
         fcx.check_asms();
 
-        if fn_sig.is_some() {
-            fcx.regionck_fn(id, body, span, wf_tys);
-        } else {
-            fcx.regionck_expr(body);
-        }
+        fcx.infcx.skip_region_resolution();
 
         fcx.resolve_type_vars_in_body(body)
     });

compiler/rustc_typeck/src/check/wfcheck.rs

@@ -62,7 +62,10 @@ pub(super) fn with_fcx<F>(&mut self, f: F)
             }
             let wf_tys = f(&fcx);
             fcx.select_all_obligations_or_error();
-            fcx.regionck_item(id, span, wf_tys);
+
+            let mut outlives_environment = OutlivesEnvironment::new(param_env);
+            outlives_environment.add_implied_bounds(&fcx.infcx, wf_tys, id);
+            fcx.infcx.check_region_obligations_and_report_errors(&outlives_environment);
         });
     }
 }
@@ -655,13 +658,12 @@ fn resolve_regions_with_wf_tys<'tcx>(
     // call individually.
     tcx.infer_ctxt().enter(|infcx| {
         let mut outlives_environment = OutlivesEnvironment::new(param_env);
-        outlives_environment.add_implied_bounds(&infcx, wf_tys.clone(), id, DUMMY_SP);
-        outlives_environment.save_implied_bounds(id);
-        let region_bound_pairs = outlives_environment.region_bound_pairs_map().get(&id).unwrap();
+        outlives_environment.add_implied_bounds(&infcx, wf_tys.clone(), id);
+        let region_bound_pairs = outlives_environment.region_bound_pairs();
 
         add_constraints(&infcx, region_bound_pairs);
 
-        let errors = infcx.resolve_regions(id.expect_owner().to_def_id(), &outlives_environment);
+        let errors = infcx.resolve_regions(&outlives_environment);
 
         debug!(?errors, "errors");
 

compiler/rustc_typeck/src/coherence/builtin.rs

@@ -349,7 +349,7 @@ fn visit_implementation_of_dispatch_from_dyn<'tcx>(tcx: TyCtxt<'tcx>, impl_did:
 
                     // Finally, resolve all regions.
                     let outlives_env = OutlivesEnvironment::new(param_env);
-                    infcx.resolve_regions_and_report_errors(impl_did.to_def_id(), &outlives_env);
+                    infcx.resolve_regions_and_report_errors(&outlives_env);
                 }
             }
             _ => {
@@ -606,7 +606,7 @@ pub fn coerce_unsized_info<'tcx>(tcx: TyCtxt<'tcx>, impl_did: DefId) -> CoerceUn
 
         // Finally, resolve all regions.
         let outlives_env = OutlivesEnvironment::new(param_env);
-        infcx.resolve_regions_and_report_errors(impl_did.to_def_id(), &outlives_env);
+        infcx.resolve_regions_and_report_errors(&outlives_env);
 
         CoerceUnsizedInfo { custom_kind: kind }
     })

compiler/rustc_typeck/src/impl_wf_check/min_specialization.rs

@@ -150,7 +150,7 @@ fn get_impl_substs<'tcx>(
 
     // Conservatively use an empty `ParamEnv`.
     let outlives_env = OutlivesEnvironment::new(ty::ParamEnv::empty());
-    infcx.resolve_regions_and_report_errors(impl1_def_id.to_def_id(), &outlives_env);
+    infcx.resolve_regions_and_report_errors(&outlives_env);
     let Ok(impl2_substs) = infcx.fully_resolve(impl2_substs) else {
         let span = tcx.def_span(impl1_def_id);
         tcx.sess.emit_err(SubstsOnOverriddenImpl { span });

compiler/rustc_typeck/src/outlives/outlives_bounds.rs

 use rustc_hir as hir;
 use rustc_middle::ty::{self, Ty};
-use rustc_span::source_map::Span;
 use rustc_trait_selection::infer::InferCtxt;
 use rustc_trait_selection::traits::query::type_op::{self, TypeOp, TypeOpOutput};
 use rustc_trait_selection::traits::query::NoSolution;
@@ -14,7 +13,6 @@ fn implied_outlives_bounds(
         param_env: ty::ParamEnv<'tcx>,
         body_id: hir::HirId,
         ty: Ty<'tcx>,
-        span: Span,
     ) -> Vec<OutlivesBound<'tcx>>;
 }
 
@@ -38,16 +36,14 @@ impl<'cx, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'cx, 'tcx> {
     ///   Note that this may cause outlives obligations to be injected
     ///   into the inference context with this body-id.
     /// - `ty`, the type that we are supposed to assume is WF.
-    /// - `span`, a span to use when normalizing, hopefully not important,
-    ///   might be useful if a `bug!` occurs.
-    #[instrument(level = "debug", skip(self, param_env, body_id, span))]
+    #[instrument(level = "debug", skip(self, param_env, body_id))]
     fn implied_outlives_bounds(
         &self,
         param_env: ty::ParamEnv<'tcx>,
         body_id: hir::HirId,
         ty: Ty<'tcx>,
-        span: Span,
     ) -> Vec<OutlivesBound<'tcx>> {
+        let span = self.tcx.hir().span(body_id);
         let result = param_env
             .and(type_op::implied_outlives_bounds::ImpliedOutlivesBounds { ty })
             .fully_perform(self);