Rollup merge of rust-lang#158360 - oli-obk:borrowck-cleanups, r=lcnr

Various borrowck cleanups and param_env/opaque_types_defined_by query simplifications for typeck children

Various things I noticed while figuring out how to best allow changing some borrowck errors into FCWs

cc @rust-lang/types for the typeck children stuff, in case I missed some memo and am undoing some work

r? @ghost need perf first

Author: JonathanBrouwer

compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs

@@ -706,7 +706,7 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, 'tcx> {
             Some(Cause::LiveVar(..) | Cause::DropVar(..)) | None => {
                 // Here, under NLL: no cause was found. Under polonius: no cause was found, or a
                 // boring local was found, which we ignore like NLLs do to match its diagnostics.
-                if let Some(region) = self.to_error_region_vid(borrow_region_vid) {
+                if let Some(region) = self.regioncx.to_error_region_vid(borrow_region_vid) {
                     let (category, from_closure, span, region_name, path) =
                         self.free_region_constraint_info(borrow_region_vid, region);
                     if let Some(region_name) = region_name {

compiler/rustc_borrowck/src/diagnostics/mod.rs

@@ -116,11 +116,42 @@ impl<'infcx, 'tcx> BorrowckDiagnosticsBuffer<'infcx, 'tcx> {
     pub(crate) fn buffer_non_error(&mut self, diag: Diag<'infcx, ()>) {
         self.buffered_diags.push(BufferedDiag::NonError(diag));
     }
+    pub(crate) fn buffer_error(&mut self, diag: Diag<'infcx>) {
+        self.buffered_diags.push(BufferedDiag::Error(diag));
+    }
+
+    pub(crate) fn emit_errors(&mut self) -> Option<ErrorGuaranteed> {
+        let mut res = None;
+
+        // Buffer any move errors that we collected and de-duplicated.
+        for (_, (_, diag)) in std::mem::take(&mut self.buffered_move_errors) {
+            // We have already set tainted for this error, so just buffer it.
+            self.buffer_error(diag);
+        }
+        for (_, (mut diag, count)) in std::mem::take(&mut self.buffered_mut_errors) {
+            if count > 10 {
+                diag.note(format!("...and {} other attempted mutable borrows", count - 10));
+            }
+            self.buffer_error(diag);
+        }
+
+        if !self.buffered_diags.is_empty() {
+            self.buffered_diags.sort_by_key(|buffered_diag| buffered_diag.sort_span());
+            for buffered_diag in self.buffered_diags.drain(..) {
+                match buffered_diag {
+                    BufferedDiag::Error(diag) => res = Some(diag.emit()),
+                    BufferedDiag::NonError(diag) => diag.emit(),
+                }
+            }
+        }
+
+        res
+    }
 }
 
 impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
     pub(crate) fn buffer_error(&mut self, diag: Diag<'infcx>) {
-        self.diags_buffer.buffered_diags.push(BufferedDiag::Error(diag));
+        self.diags_buffer.buffer_error(diag);
     }
 
     pub(crate) fn buffer_non_error(&mut self, diag: Diag<'infcx, ()>) {
@@ -152,34 +183,6 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
         self.diags_buffer.buffered_mut_errors.insert(span, (diag, count));
     }
 
-    pub(crate) fn emit_errors(&mut self) -> Option<ErrorGuaranteed> {
-        let mut res = self.infcx.tainted_by_errors();
-
-        // Buffer any move errors that we collected and de-duplicated.
-        for (_, (_, diag)) in std::mem::take(&mut self.diags_buffer.buffered_move_errors) {
-            // We have already set tainted for this error, so just buffer it.
-            self.buffer_error(diag);
-        }
-        for (_, (mut diag, count)) in std::mem::take(&mut self.diags_buffer.buffered_mut_errors) {
-            if count > 10 {
-                diag.note(format!("...and {} other attempted mutable borrows", count - 10));
-            }
-            self.buffer_error(diag);
-        }
-
-        if !self.diags_buffer.buffered_diags.is_empty() {
-            self.diags_buffer.buffered_diags.sort_by_key(|buffered_diag| buffered_diag.sort_span());
-            for buffered_diag in self.diags_buffer.buffered_diags.drain(..) {
-                match buffered_diag {
-                    BufferedDiag::Error(diag) => res = Some(diag.emit()),
-                    BufferedDiag::NonError(diag) => diag.emit(),
-                }
-            }
-        }
-
-        res
-    }
-
     pub(crate) fn has_buffered_diags(&self) -> bool {
         self.diags_buffer.buffered_diags.is_empty()
     }

compiler/rustc_borrowck/src/diagnostics/opaque_types.rs

@@ -28,11 +28,10 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
         }
 
         let infcx = self.infcx;
-        let mut guar = None;
         let mut last_unexpected_hidden_region: Option<(Span, Ty<'_>, ty::OpaqueTypeKey<'tcx>)> =
             None;
         for error in errors {
-            guar = Some(match error {
+            match error {
                 DeferredOpaqueTypeError::InvalidOpaqueTypeArgs(err) => err.report(infcx),
                 DeferredOpaqueTypeError::LifetimeMismatchOpaqueParam(err) => {
                     infcx.dcx().emit_err(err)
@@ -82,11 +81,8 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                         )
                     ),
                 ),
-            });
+            };
         }
-        let guar = guar.unwrap();
-        self.root_cx.set_tainted_by_errors(guar);
-        self.infcx.set_tainted_by_errors(guar);
     }
 
     /// Try to note when an opaque is involved in a borrowck error and that

compiler/rustc_borrowck/src/diagnostics/region_errors.rs

@@ -28,6 +28,7 @@ use rustc_trait_selection::traits::{Obligation, ObligationCtxt};
 use tracing::{debug, instrument, trace};
 
 use super::{LIMITATION_NOTE, OutlivesSuggestionBuilder, RegionName, RegionNameSource};
+use crate::consumers::RegionInferenceContext;
 use crate::nll::ConstraintDescription;
 use crate::region_infer::{BlameConstraint, TypeTest};
 use crate::session_diagnostics::{
@@ -134,28 +135,28 @@ pub(crate) struct ErrorConstraintInfo<'tcx> {
     pub(super) span: Span,
 }
 
-impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
+impl<'tcx> RegionInferenceContext<'tcx> {
     /// Converts a region inference variable into a `ty::Region` that
     /// we can use for error reporting. If `r` is universally bound,
     /// then we use the name that we have on record for it. If `r` is
     /// existentially bound, then we check its inferred value and try
     /// to find a good name from that. Returns `None` if we can't find
     /// one (e.g., this is just some random part of the CFG).
     pub(super) fn to_error_region(&self, r: RegionVid) -> Option<ty::Region<'tcx>> {
-        self.to_error_region_vid(r).and_then(|r| self.regioncx.region_definition(r).external_name)
+        self.to_error_region_vid(r).and_then(|r| self.region_definition(r).external_name)
     }
 
     /// Returns the `RegionVid` corresponding to the region returned by
     /// `to_error_region`.
     pub(super) fn to_error_region_vid(&self, r: RegionVid) -> Option<RegionVid> {
-        if self.regioncx.universal_regions().is_universal_region(r) {
+        if self.universal_regions().is_universal_region(r) {
             Some(r)
         } else {
             // We just want something nameable, even if it's not
             // actually an upper bound.
-            let upper_bound = self.regioncx.approx_universal_upper_bound(r);
+            let upper_bound = self.approx_universal_upper_bound(r);
 
-            if self.regioncx.upper_bound_in_region_scc(r, upper_bound) {
+            if self.upper_bound_in_region_scc(r, upper_bound) {
                 self.to_error_region_vid(upper_bound)
             } else {
                 None
@@ -179,14 +180,16 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
         if let Some(r) = self.to_error_region(fr)
             && let ty::ReLateParam(late_param) = r.kind()
             && let ty::LateParamRegionKind::ClosureEnv = late_param.kind
-            && let DefiningTy::Closure(_, args) = self.regioncx.universal_regions().defining_ty
+            && let DefiningTy::Closure(_, args) = self.universal_regions().defining_ty
         {
             return args.as_closure().kind() == ty::ClosureKind::FnMut;
         }
 
         false
     }
+}
 
+impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
     // For generic associated types (GATs) which implied 'static requirement
     // from higher-ranked trait bounds (HRTB). Try to locate span of the trait
     // and the span which bounded to the trait for adding 'static lifetime suggestion
@@ -309,12 +312,12 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                 RegionErrorKind::TypeTestError { type_test } => {
                     // Try to convert the lower-bound region into something named we can print for
                     // the user.
-                    let lower_bound_region = self.to_error_region(type_test.lower_bound);
+                    let lower_bound_region = self.regioncx.to_error_region(type_test.lower_bound);
 
                     let type_test_span = type_test.span;
 
                     if let Some(lower_bound_region) = lower_bound_region {
-                        let generic_ty = self.name_regions(
+                        let generic_ty = self.regioncx.name_regions(
                             self.infcx.tcx,
                             type_test.generic_kind.to_ty(self.infcx.tcx),
                         );
@@ -324,7 +327,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                             self.body.source.def_id().expect_local(),
                             type_test_span,
                             Some(origin),
-                            self.name_regions(self.infcx.tcx, type_test.generic_kind),
+                            self.regioncx.name_regions(self.infcx.tcx, type_test.generic_kind),
                             lower_bound_region,
                         ));
                     } else {
@@ -450,7 +453,9 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
         debug!("report_region_error: category={:?} {:?} {:?}", category, cause, variance_info);
 
         // Check if we can use one of the "nice region errors".
-        if let (Some(f), Some(o)) = (self.to_error_region(fr), self.to_error_region(outlived_fr)) {
+        if let (Some(f), Some(o)) =
+            (self.regioncx.to_error_region(fr), self.regioncx.to_error_region(outlived_fr))
+        {
             let infer_err = self.infcx.err_ctxt();
             let nice =
                 NiceRegionError::new_from_span(&infer_err, self.mir_def_id(), cause.span, o, f);
@@ -481,7 +486,9 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                 d.note("meoow :c");
                 d
             }
-            (ConstraintCategory::Return(kind), true, false) if self.is_closure_fn_mut(fr) => {
+            (ConstraintCategory::Return(kind), true, false)
+                if self.regioncx.is_closure_fn_mut(fr) =>
+            {
                 self.report_fnmut_error(&errci, kind)
             }
             (ConstraintCategory::Assignment, true, false)
@@ -736,7 +743,10 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
         // Only show an extra note if we can find an 'error region' for both of the region
         // variables. This avoids showing a noisy note that just mentions 'synthetic' regions
         // that don't help the user understand the error.
-        match (self.to_error_region(errci.fr), self.to_error_region(errci.outlived_fr)) {
+        match (
+            self.regioncx.to_error_region(errci.fr),
+            self.regioncx.to_error_region(errci.outlived_fr),
+        ) {
             (Some(f), Some(o)) => {
                 self.maybe_suggest_constrain_dyn_trait_impl(&mut diag, f, o, category);
 
@@ -842,7 +852,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
         outlived_fr: RegionVid,
     ) {
         if let (Some(f), Some(outlived_f)) =
-            (self.to_error_region(fr), self.to_error_region(outlived_fr))
+            (self.regioncx.to_error_region(fr), self.regioncx.to_error_region(outlived_fr))
         {
             if outlived_f.kind() != ty::ReStatic {
                 return;
@@ -1013,7 +1023,9 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
     }
 
     fn suggest_adding_lifetime_params(&self, diag: &mut Diag<'_>, sub: RegionVid, sup: RegionVid) {
-        let (Some(sub), Some(sup)) = (self.to_error_region(sub), self.to_error_region(sup)) else {
+        let (Some(sub), Some(sup)) =
+            (self.regioncx.to_error_region(sub), self.regioncx.to_error_region(sup))
+        else {
             return;
         };
 

compiler/rustc_borrowck/src/diagnostics/region_name.rs

@@ -283,7 +283,7 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, 'tcx> {
     /// named variants.
     #[instrument(level = "trace", skip(self))]
     fn give_name_from_error_region(&self, fr: RegionVid) -> Option<RegionName> {
-        let error_region = self.to_error_region(fr)?;
+        let error_region = self.regioncx.to_error_region(fr)?;
 
         let tcx = self.infcx.tcx;
 
@@ -1015,7 +1015,7 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, 'tcx> {
         &self,
         fr: RegionVid,
     ) -> Option<RegionName> {
-        let ty::ReEarlyParam(region) = self.to_error_region(fr)?.kind() else {
+        let ty::ReEarlyParam(region) = self.regioncx.to_error_region(fr)?.kind() else {
             return None;
         };
         if region.is_named() {
@@ -1050,7 +1050,7 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, 'tcx> {
         &self,
         fr: RegionVid,
     ) -> Option<RegionName> {
-        let ty::ReEarlyParam(region) = self.to_error_region(fr)?.kind() else {
+        let ty::ReEarlyParam(region) = self.regioncx.to_error_region(fr)?.kind() else {
             return None;
         };
         if region.is_named() {

compiler/rustc_borrowck/src/lib.rs

@@ -48,6 +48,7 @@ use rustc_mir_dataflow::points::DenseLocationMap;
 use rustc_mir_dataflow::{Analysis, EntryStates, Results, ResultsVisitor, visit_results};
 use rustc_session::lint::builtin::{TAIL_EXPR_DROP_ORDER, UNUSED_MUT};
 use rustc_span::{ErrorGuaranteed, Span, Symbol};
+use rustc_trait_selection::traits::query::type_op::{QueryTypeOp, TypeOp, TypeOpOutput};
 use smallvec::SmallVec;
 use tracing::{debug, instrument};
 
@@ -323,7 +324,6 @@ fn borrowck_collect_region_constraints<'tcx>(
     let input_promoted: &IndexSlice<_, _> = &promoted.borrow();
     if let Some(e) = input_body.tainted_by_errors {
         infcx.set_tainted_by_errors(e);
-        root_cx.set_tainted_by_errors(e);
     }
 
     // Replace all regions with fresh inference variables. This
@@ -571,15 +571,16 @@ fn borrowck_check_region_constraints<'tcx>(
 
     debug!("mbcx.used_mut: {:?}", mbcx.used_mut);
     mbcx.lint_unused_mut();
-    if let Some(guar) = mbcx.emit_errors() {
-        mbcx.root_cx.set_tainted_by_errors(guar);
-    }
 
     let result = PropagatedBorrowCheckResults {
         closure_requirements: opt_closure_req,
         used_mut_upvars: mbcx.used_mut_upvars,
     };
 
+    if let Some(guar) = mbcx.diags_buffer.emit_errors().or(infcx.tainted_by_errors()) {
+        root_cx.set_tainted_by_errors(guar);
+    }
+
     if let Some(consumer) = &mut root_cx.consumer {
         consumer.insert_body(
             def,
@@ -707,6 +708,14 @@ impl<'tcx> BorrowckInferCtxt<'tcx> {
 
         next_region
     }
+
+    fn fully_perform<Q: QueryTypeOp<'tcx> + TypeVisitable<TyCtxt<'tcx>>>(
+        &self,
+        q: Q,
+        span: Span,
+    ) -> Result<TypeOpOutput<'tcx, ty::ParamEnvAnd<'tcx, Q>>, ErrorGuaranteed> {
+        self.param_env.and(q).fully_perform(&self.infcx, self.root_def_id, span)
+    }
 }
 
 impl<'tcx> Deref for BorrowckInferCtxt<'tcx> {
@@ -718,7 +727,7 @@ impl<'tcx> Deref for BorrowckInferCtxt<'tcx> {
 }
 
 pub(crate) struct MirBorrowckCtxt<'a, 'infcx, 'tcx> {
-    root_cx: &'a mut BorrowCheckRootCtxt<'tcx>,
+    root_cx: &'a BorrowCheckRootCtxt<'tcx>,
     infcx: &'infcx BorrowckInferCtxt<'tcx>,
     body: &'a Body<'tcx>,
     move_data: &'a MoveData<'tcx>,

compiler/rustc_borrowck/src/nll.rs

@@ -111,7 +111,7 @@ pub(crate) fn compute_closure_requirements_modulo_opaques<'tcx>(
 ///
 /// This may result in errors being reported.
 pub(crate) fn compute_regions<'tcx>(
-    root_cx: &mut BorrowCheckRootCtxt<'tcx>,
+    root_cx: &BorrowCheckRootCtxt<'tcx>,
     infcx: &BorrowckInferCtxt<'tcx>,
     body: &Body<'tcx>,
     location_table: &PoloniusLocationTable,

compiler/rustc_borrowck/src/root_cx.rs

@@ -72,7 +72,7 @@ impl<'tcx> BorrowCheckRootCtxt<'tcx> {
     }
 
     pub(super) fn used_mut_upvars(
-        &mut self,
+        &self,
         nested_body_def_id: LocalDefId,
     ) -> &SmallVec<[FieldIdx; 8]> {
         &self.propagated_borrowck_results[&nested_body_def_id].used_mut_upvars

compiler/rustc_borrowck/src/type_check/constraint_conversion.rs

@@ -11,7 +11,7 @@ use rustc_middle::ty::{
     self, GenericArgKind, Ty, TyCtxt, TypeFoldable, TypeVisitableExt, elaborate, fold_regions,
 };
 use rustc_span::Span;
-use rustc_trait_selection::traits::query::type_op::{TypeOp, TypeOpOutput};
+use rustc_trait_selection::traits::query::type_op::TypeOpOutput;
 use tracing::{debug, instrument};
 
 use crate::constraints::OutlivesConstraint;
@@ -287,11 +287,7 @@ impl<'a, 'tcx> ConstraintConversion<'a, 'tcx> {
             ConstraintCategory<'tcx>,
         )>,
     ) -> Ty<'tcx> {
-        match self.infcx.param_env.and(DeeplyNormalize { value: ty }).fully_perform(
-            self.infcx,
-            self.infcx.root_def_id,
-            self.span,
-        ) {
+        match self.infcx.fully_perform(DeeplyNormalize { value: ty }, self.span) {
             Ok(TypeOpOutput { output: ty, constraints, .. }) => {
                 // FIXME(higher_ranked_auto): What should we do with the assumptions here?
                 if let Some(QueryRegionConstraints { constraints, assumptions: _ }) = constraints {