Auto merge of rust-lang#132623 - nnethercote:rustc_borrowck-cleanups-…

…2, r=Nadrieril

`rustc_borrowck` cleanups, part 2

The code under `do_mir_borrowck` is pretty messy, especially the various types like `MirBorrowckCtxt`, `BorrowckInferCtxt`, `MirTypeckResults`, `MirTypeckRegionConstraints`, `CreateResult`, `TypeChecker`, `TypeVerifier`, `LivenessContext`, `LivenessResults`. This PR does some tidying up, though there's still plenty of mess left afterwards.

A sequel to rust-lang#132250.

r? `@compiler-errors`

compiler/rustc_borrowck/src/diagnostics/bound_region_errors.rs

@@ -60,7 +60,7 @@ impl<'tcx> UniverseInfo<'tcx> {
             UniverseInfo::RelateTys { expected, found } => {
                 let err = mbcx.infcx.err_ctxt().report_mismatched_types(
                     &cause,
-                    mbcx.param_env,
+                    mbcx.infcx.param_env,
                     expected,
                     found,
                     TypeError::RegionsPlaceholderMismatch,

compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs

@@ -266,7 +266,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                 }
             }
 
-            if self.param_env.caller_bounds().iter().any(|c| {
+            if self.infcx.param_env.caller_bounds().iter().any(|c| {
                 c.as_trait_clause().is_some_and(|pred| {
                     pred.skip_binder().self_ty() == ty && self.infcx.tcx.is_fn_trait(pred.def_id())
                 })
@@ -682,13 +682,13 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                 // Normalize before comparing to see through type aliases and projections.
                 let old_ty = ty::EarlyBinder::bind(ty).instantiate(tcx, generic_args);
                 let new_ty = ty::EarlyBinder::bind(ty).instantiate(tcx, new_args);
-                if let Ok(old_ty) =
-                    tcx.try_normalize_erasing_regions(self.infcx.typing_env(self.param_env), old_ty)
-                    && let Ok(new_ty) = tcx.try_normalize_erasing_regions(
-                        self.infcx.typing_env(self.param_env),
-                        new_ty,
-                    )
-                {
+                if let Ok(old_ty) = tcx.try_normalize_erasing_regions(
+                    self.infcx.typing_env(self.infcx.param_env),
+                    old_ty,
+                ) && let Ok(new_ty) = tcx.try_normalize_erasing_regions(
+                    self.infcx.typing_env(self.infcx.param_env),
+                    new_ty,
+                ) {
                     old_ty == new_ty
                 } else {
                     false
@@ -707,15 +707,16 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
             // Test the callee's predicates, substituting in `ref_ty` for the moved argument type.
             clauses.instantiate(tcx, new_args).predicates.iter().all(|&(mut clause)| {
                 // Normalize before testing to see through type aliases and projections.
-                if let Ok(normalized) =
-                    tcx.try_normalize_erasing_regions(self.infcx.typing_env(self.param_env), clause)
-                {
+                if let Ok(normalized) = tcx.try_normalize_erasing_regions(
+                    self.infcx.typing_env(self.infcx.param_env),
+                    clause,
+                ) {
                     clause = normalized;
                 }
                 self.infcx.predicate_must_hold_modulo_regions(&Obligation::new(
                     tcx,
                     ObligationCause::dummy(),
-                    self.param_env,
+                    self.infcx.param_env,
                     clause,
                 ))
             })
@@ -904,7 +905,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
         let ty = moved_place.ty(self.body, self.infcx.tcx).ty;
         debug!("ty: {:?}, kind: {:?}", ty, ty.kind());
 
-        let Some(assign_value) = self.infcx.err_ctxt().ty_kind_suggestion(self.param_env, ty)
+        let Some(assign_value) = self.infcx.err_ctxt().ty_kind_suggestion(self.infcx.param_env, ty)
         else {
             return;
         };
@@ -1304,7 +1305,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
     pub(crate) fn implements_clone(&self, ty: Ty<'tcx>) -> bool {
         let Some(clone_trait_def) = self.infcx.tcx.lang_items().clone_trait() else { return false };
         self.infcx
-            .type_implements_trait(clone_trait_def, [ty], self.param_env)
+            .type_implements_trait(clone_trait_def, [ty], self.infcx.param_env)
             .must_apply_modulo_regions()
     }
 
@@ -1437,7 +1438,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
         let ocx = ObligationCtxt::new_with_diagnostics(self.infcx);
         let cause = ObligationCause::misc(span, self.mir_def_id());
 
-        ocx.register_bound(cause, self.param_env, ty, def_id);
+        ocx.register_bound(cause, self.infcx.param_env, ty, def_id);
         let errors = ocx.select_all_or_error();
 
         // Only emit suggestion if all required predicates are on generic
@@ -1957,7 +1958,8 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                 && let ty::Ref(_, inner, _) = rcvr_ty.kind()
                 && let inner = inner.peel_refs()
                 && (Holds { ty: inner }).visit_ty(local_ty).is_break()
-                && let None = self.infcx.type_implements_trait_shallow(clone, inner, self.param_env)
+                && let None =
+                    self.infcx.type_implements_trait_shallow(clone, inner, self.infcx.param_env)
             {
                 err.span_label(
                     span,
@@ -1989,7 +1991,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
             let obligation = Obligation::new(
                 self.infcx.tcx,
                 ObligationCause::dummy(),
-                self.param_env,
+                self.infcx.param_env,
                 trait_ref,
             );
             self.infcx.err_ctxt().suggest_derive(
@@ -3398,7 +3400,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
             if let Some(iter_trait) = tcx.get_diagnostic_item(sym::Iterator)
                 && self
                     .infcx
-                    .type_implements_trait(iter_trait, [return_ty], self.param_env)
+                    .type_implements_trait(iter_trait, [return_ty], self.infcx.param_env)
                     .must_apply_modulo_regions()
             {
                 err.span_suggestion_hidden(
@@ -3839,14 +3841,15 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                     tcx.get_diagnostic_item(sym::deref_target).and_then(|deref_target| {
                         Instance::try_resolve(
                             tcx,
-                            self.infcx.typing_env(self.param_env),
+                            self.infcx.typing_env(self.infcx.param_env),
                             deref_target,
                             method_args,
                         )
                         .transpose()
                     });
                 if let Some(Ok(instance)) = deref_target {
-                    let deref_target_ty = instance.ty(tcx, self.infcx.typing_env(self.param_env));
+                    let deref_target_ty =
+                        instance.ty(tcx, self.infcx.typing_env(self.infcx.param_env));
                     err.note(format!("borrow occurs due to deref coercion to `{deref_target_ty}`"));
                     err.span_note(tcx.def_span(instance.def_id()), "deref defined here");
                 }

compiler/rustc_borrowck/src/diagnostics/mod.rs

@@ -864,7 +864,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
 
             let kind = call_kind(
                 self.infcx.tcx,
-                self.infcx.typing_env(self.param_env),
+                self.infcx.typing_env(self.infcx.param_env),
                 method_did,
                 method_args,
                 *fn_span,
@@ -1160,7 +1160,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                         let suggest = match tcx.get_diagnostic_item(sym::IntoIterator) {
                             Some(def_id) => type_known_to_meet_bound_modulo_regions(
                                 self.infcx,
-                                self.param_env,
+                                self.infcx.param_env,
                                 Ty::new_imm_ref(tcx, tcx.lifetimes.re_erased, ty),
                                 def_id,
                             ),
@@ -1224,7 +1224,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                                 BoundRegionConversionTime::FnCall,
                                 tcx.fn_sig(method_did).instantiate(tcx, method_args).input(0),
                             )
-                            && self.infcx.can_eq(self.param_env, ty, self_ty)
+                            && self.infcx.can_eq(self.infcx.param_env, ty, self_ty)
                         {
                             err.subdiagnostic(CaptureReasonSuggest::FreshReborrow {
                                 span: move_span.shrink_to_hi(),
@@ -1258,7 +1258,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                             if let Some(errors) = self.infcx.type_implements_trait_shallow(
                                 clone_trait,
                                 ty,
-                                self.param_env,
+                                self.infcx.param_env,
                             ) && !has_sugg
                             {
                                 let msg = match &errors[..] {

compiler/rustc_borrowck/src/diagnostics/move_errors.rs

@@ -305,7 +305,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
         let Some(copy_trait_def) = self.infcx.tcx.lang_items().copy_trait() else { return false };
         // This is only going to be ambiguous if there are incoherent impls, because otherwise
         // ambiguity should never happen in MIR.
-        self.infcx.type_implements_trait(copy_trait_def, [ty], self.param_env).may_apply()
+        self.infcx.type_implements_trait(copy_trait_def, [ty], self.infcx.param_env).may_apply()
     }
 
     fn report_cannot_move_from_static(&mut self, place: Place<'tcx>, span: Span) -> Diag<'infcx> {

compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs

@@ -1242,7 +1242,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                             .type_implements_trait_shallow(
                                 clone_trait,
                                 ty.peel_refs(),
-                                self.param_env,
+                                self.infcx.param_env,
                             )
                             .as_deref()
                         {
@@ -1279,7 +1279,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                                 let obligation = traits::Obligation::new(
                                     self.infcx.tcx,
                                     traits::ObligationCause::dummy(),
-                                    self.param_env,
+                                    self.infcx.param_env,
                                     trait_ref,
                                 );
                                 self.infcx.err_ctxt().suggest_derive(

compiler/rustc_borrowck/src/diagnostics/region_errors.rs

@@ -952,7 +952,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
 
             if let Ok(Some(instance)) = ty::Instance::try_resolve(
                 tcx,
-                self.infcx.typing_env(self.param_env),
+                self.infcx.typing_env(self.infcx.param_env),
                 *fn_did,
                 self.infcx.resolve_vars_if_possible(args),
             ) {
@@ -1091,7 +1091,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
             peeled_ty = ref_ty;
             count += 1;
         }
-        if !self.infcx.type_is_copy_modulo_regions(self.param_env, peeled_ty) {
+        if !self.infcx.type_is_copy_modulo_regions(self.infcx.param_env, peeled_ty) {
             return;
         }
 
@@ -1160,7 +1160,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
         let ocx = ObligationCtxt::new(&self.infcx);
         ocx.register_obligations(preds.iter().map(|(pred, span)| {
             trace!(?pred);
-            Obligation::misc(tcx, span, self.mir_def_id(), self.param_env, pred)
+            Obligation::misc(tcx, span, self.mir_def_id(), self.infcx.param_env, pred)
         }));
 
         if ocx.select_all_or_error().is_empty() && count > 0 {

compiler/rustc_borrowck/src/lib.rs

@@ -140,7 +140,6 @@ fn do_mir_borrowck<'tcx>(
 ) -> (BorrowCheckResult<'tcx>, Option<Box<BodyWithBorrowckFacts<'tcx>>>) {
     let def = input_body.source.def_id().expect_local();
     let infcx = BorrowckInferCtxt::new(tcx, def);
-    let param_env = tcx.param_env(def);
 
     let mut local_names = IndexVec::from_elem(None, &input_body.local_decls);
     for var_debug_info in &input_body.var_debug_info {
@@ -175,8 +174,7 @@ fn do_mir_borrowck<'tcx>(
     // will have a lifetime tied to the inference context.
     let mut body_owned = input_body.clone();
     let mut promoted = input_promoted.to_owned();
-    let free_regions =
-        nll::replace_regions_in_mir(&infcx, param_env, &mut body_owned, &mut promoted);
+    let free_regions = nll::replace_regions_in_mir(&infcx, &mut body_owned, &mut promoted);
     let body = &body_owned; // no further changes
 
     // FIXME(-Znext-solver): A bit dubious that we're only registering
@@ -192,7 +190,7 @@ fn do_mir_borrowck<'tcx>(
         .iter_enumerated()
         .map(|(idx, body)| (idx, MoveData::gather_moves(body, tcx, |_| true)));
 
-    let mut flow_inits = MaybeInitializedPlaces::new(tcx, body, &move_data)
+    let flow_inits = MaybeInitializedPlaces::new(tcx, body, &move_data)
         .iterate_to_fixpoint(tcx, body, Some("borrowck"))
         .into_results_cursor(body);
 
@@ -213,18 +211,12 @@ fn do_mir_borrowck<'tcx>(
         body,
         &promoted,
         &location_table,
-        param_env,
-        &mut flow_inits,
+        flow_inits,
         &move_data,
         &borrow_set,
-        tcx.closure_captures(def),
         consumer_options,
     );
 
-    // `flow_inits` is large, so we drop it as soon as possible. This reduces
-    // peak memory usage significantly on some benchmarks.
-    drop(flow_inits);
-
     // Dump MIR results into a file, if that is enabled. This let us
     // write unit-tests, as well as helping with debugging.
     nll::dump_nll_mir(&infcx, body, &regioncx, &opt_closure_req, &borrow_set);
@@ -251,7 +243,6 @@ fn do_mir_borrowck<'tcx>(
         let promoted_body = &promoted[idx];
         let mut promoted_mbcx = MirBorrowckCtxt {
             infcx: &infcx,
-            param_env,
             body: promoted_body,
             move_data: &move_data,
             location_table: &location_table, // no need to create a real one for the promoted, it is not used
@@ -291,7 +282,6 @@ fn do_mir_borrowck<'tcx>(
 
     let mut mbcx = MirBorrowckCtxt {
         infcx: &infcx,
-        param_env,
         body,
         move_data: &move_data,
         location_table: &location_table,
@@ -448,12 +438,14 @@ fn get_flow_results<'a, 'tcx>(
 pub(crate) struct BorrowckInferCtxt<'tcx> {
     pub(crate) infcx: InferCtxt<'tcx>,
     pub(crate) reg_var_to_origin: RefCell<FxIndexMap<ty::RegionVid, RegionCtxt>>,
+    pub(crate) param_env: ParamEnv<'tcx>,
 }
 
 impl<'tcx> BorrowckInferCtxt<'tcx> {
     pub(crate) fn new(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> Self {
         let infcx = tcx.infer_ctxt().build(TypingMode::analysis_in_body(tcx, def_id));
-        BorrowckInferCtxt { infcx, reg_var_to_origin: RefCell::new(Default::default()) }
+        let param_env = tcx.param_env(def_id);
+        BorrowckInferCtxt { infcx, reg_var_to_origin: RefCell::new(Default::default()), param_env }
     }
 
     pub(crate) fn next_region_var<F>(
@@ -532,7 +524,6 @@ impl<'tcx> Deref for BorrowckInferCtxt<'tcx> {
 
 struct MirBorrowckCtxt<'a, 'infcx, 'tcx> {
     infcx: &'infcx BorrowckInferCtxt<'tcx>,
-    param_env: ParamEnv<'tcx>,
     body: &'a Body<'tcx>,
     move_data: &'a MoveData<'tcx>,