Make ClosureOutlivesRequirement not rely on an unresolved type

compiler/rustc_borrowck/src/constraints/mod.rs

@@ -92,7 +92,7 @@ pub struct OutlivesConstraint<'tcx> {
     pub span: Span,
 
     /// What caused this constraint?
-    pub category: ConstraintCategory<'tcx>,
+    pub category: ConstraintCategory,
 
     /// Variance diagnostic information
     pub variance_info: VarianceDiagInfo<'tcx>,

compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs

@@ -976,7 +976,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         err: &mut Diagnostic,
         location: Location,
         issued_borrow: &BorrowData<'tcx>,
-        explanation: BorrowExplanation<'tcx>,
+        explanation: BorrowExplanation,
     ) {
         let used_in_call = matches!(
             explanation,
@@ -1326,7 +1326,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         borrow: &BorrowData<'tcx>,
         drop_span: Span,
         borrow_spans: UseSpans<'tcx>,
-        explanation: BorrowExplanation<'tcx>,
+        explanation: BorrowExplanation,
     ) -> DiagnosticBuilder<'cx, ErrorGuaranteed> {
         debug!(
             "report_local_value_does_not_live_long_enough(\
@@ -1532,7 +1532,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         drop_span: Span,
         borrow_spans: UseSpans<'tcx>,
         proper_span: Span,
-        explanation: BorrowExplanation<'tcx>,
+        explanation: BorrowExplanation,
     ) -> DiagnosticBuilder<'cx, ErrorGuaranteed> {
         if let BorrowExplanation::MustBeValidFor { category, span, from_closure: false, .. } =
             explanation
@@ -1646,7 +1646,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         borrow: &BorrowData<'tcx>,
         borrow_span: Span,
         return_span: Span,
-        category: ConstraintCategory<'tcx>,
+        category: ConstraintCategory,
         opt_place_desc: Option<&String>,
     ) -> Option<DiagnosticBuilder<'cx, ErrorGuaranteed>> {
         let return_kind = match category {
@@ -1741,7 +1741,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         use_span: UseSpans<'tcx>,
         var_span: Span,
         fr_name: &RegionName,
-        category: ConstraintCategory<'tcx>,
+        category: ConstraintCategory,
         constraint_span: Span,
         captured_var: &str,
     ) -> DiagnosticBuilder<'cx, ErrorGuaranteed> {

compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs

@@ -21,7 +21,7 @@ use crate::{
 use super::{find_use, RegionName, UseSpans};
 
 #[derive(Debug)]
-pub(crate) enum BorrowExplanation<'tcx> {
+pub(crate) enum BorrowExplanation {
     UsedLater(LaterUseKind, Span, Option<Span>),
     UsedLaterInLoop(LaterUseKind, Span, Option<Span>),
     UsedLaterWhenDropped {
@@ -30,7 +30,7 @@ pub(crate) enum BorrowExplanation<'tcx> {
         should_note_order: bool,
     },
     MustBeValidFor {
-        category: ConstraintCategory<'tcx>,
+        category: ConstraintCategory,
         from_closure: bool,
         span: Span,
         region_name: RegionName,
@@ -49,7 +49,7 @@ pub(crate) enum LaterUseKind {
     Other,
 }
 
-impl<'tcx> BorrowExplanation<'tcx> {
+impl<'tcx> BorrowExplanation {
     pub(crate) fn is_explained(&self) -> bool {
         !matches!(self, BorrowExplanation::Unexplained)
     }
@@ -284,7 +284,7 @@ impl<'tcx> BorrowExplanation<'tcx> {
     fn add_lifetime_bound_suggestion_to_diagnostic(
         &self,
         err: &mut Diagnostic,
-        category: &ConstraintCategory<'tcx>,
+        category: &ConstraintCategory,
         span: Span,
         region_name: &RegionName,
     ) {
@@ -316,7 +316,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         &self,
         borrow_region: RegionVid,
         outlived_region: RegionVid,
-    ) -> (ConstraintCategory<'tcx>, bool, Span, Option<RegionName>, Vec<ExtraConstraintInfo>) {
+    ) -> (ConstraintCategory, bool, Span, Option<RegionName>, Vec<ExtraConstraintInfo>) {
         let (blame_constraint, extra_info) = self.regioncx.best_blame_constraint(
             borrow_region,
             NllRegionVariableOrigin::FreeRegion,
@@ -348,7 +348,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         location: Location,
         borrow: &BorrowData<'tcx>,
         kind_place: Option<(WriteKind, Place<'tcx>)>,
-    ) -> BorrowExplanation<'tcx> {
+    ) -> BorrowExplanation {
         let regioncx = &self.regioncx;
         let body: &Body<'_> = &self.body;
         let tcx = self.infcx.tcx;

compiler/rustc_borrowck/src/diagnostics/outlives_suggestion.rs

@@ -161,7 +161,7 @@ impl OutlivesSuggestionBuilder {
     pub(crate) fn intermediate_suggestion(
         &mut self,
         mbcx: &MirBorrowckCtxt<'_, '_>,
-        errci: &ErrorConstraintInfo<'_>,
+        errci: &ErrorConstraintInfo,
         diag: &mut Diagnostic,
     ) {
         // Emit an intermediate note.

compiler/rustc_borrowck/src/diagnostics/region_errors.rs

@@ -2,6 +2,7 @@
 #![deny(rustc::diagnostic_outside_of_impl)]
 //! Error reporting machinery for lifetime errors.
 
+use either::Either;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::{Applicability, Diagnostic, DiagnosticBuilder, ErrorGuaranteed, MultiSpan};
 use rustc_hir::def_id::DefId;
@@ -16,7 +17,7 @@ use rustc_infer::infer::{
     NllRegionVariableOrigin, RelateParamBound,
 };
 use rustc_middle::hir::place::PlaceBase;
-use rustc_middle::mir::{ConstraintCategory, ReturnConstraint};
+use rustc_middle::mir::{ConstraintCategory, ReturnConstraint, TerminatorKind};
 use rustc_middle::ty::subst::InternalSubsts;
 use rustc_middle::ty::Region;
 use rustc_middle::ty::TypeVisitor;
@@ -39,7 +40,7 @@ use crate::{
     MirBorrowckCtxt,
 };
 
-impl<'tcx> ConstraintDescription for ConstraintCategory<'tcx> {
+impl ConstraintDescription for ConstraintCategory {
     fn description(&self) -> &'static str {
         // Must end with a space. Allows for empty names to be provided.
         match self {
@@ -115,15 +116,15 @@ pub(crate) enum RegionErrorKind<'tcx> {
 
 /// Information about the various region constraints involved in a borrow checker error.
 #[derive(Clone, Debug)]
-pub struct ErrorConstraintInfo<'tcx> {
+pub struct ErrorConstraintInfo {
     // fr: outlived_fr
     pub(super) fr: RegionVid,
     pub(super) fr_is_local: bool,
     pub(super) outlived_fr: RegionVid,
     pub(super) outlived_fr_is_local: bool,
 
     // Category and span for best blame constraint
-    pub(super) category: ConstraintCategory<'tcx>,
+    pub(super) category: ConstraintCategory,
     pub(super) span: Span,
 }
 
@@ -498,7 +499,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
     /// ```
     fn report_fnmut_error(
         &self,
-        errci: &ErrorConstraintInfo<'tcx>,
+        errci: &ErrorConstraintInfo,
         kind: ReturnConstraint,
     ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
         let ErrorConstraintInfo { outlived_fr, span, .. } = errci;
@@ -571,7 +572,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
     #[instrument(level = "debug", skip(self))]
     fn report_escaping_data_error(
         &self,
-        errci: &ErrorConstraintInfo<'tcx>,
+        errci: &ErrorConstraintInfo,
     ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
         let ErrorConstraintInfo { span, category, .. } = errci;
 
@@ -675,7 +676,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
     /// ```
     fn report_general_error(
         &self,
-        errci: &ErrorConstraintInfo<'tcx>,
+        errci: &ErrorConstraintInfo,
     ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
         let ErrorConstraintInfo {
             fr,
@@ -788,15 +789,20 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
         diag: &mut Diagnostic,
         f: Region<'tcx>,
         o: Region<'tcx>,
-        category: &ConstraintCategory<'tcx>,
+        category: &ConstraintCategory,
     ) {
         if !o.is_static() {
             return;
         }
 
         let tcx = self.infcx.tcx;
 
-        let instance = if let ConstraintCategory::CallArgument(Some(func_ty)) = category {
+        let instance =
+            if let ConstraintCategory::CallArgument(location) = category
+                && let Either::Right(term) = self.body.stmt_at(*location)
+                && let TerminatorKind::Call { func, .. } = &term.kind
+        {
+            let func_ty = func.ty(self.body, tcx);
             let (fn_did, substs) = match func_ty.kind() {
                 ty::FnDef(fn_did, substs) => (fn_did, substs),
                 _ => return,

compiler/rustc_borrowck/src/region_infer/mod.rs

@@ -91,7 +91,7 @@ pub struct RegionInferenceContext<'tcx> {
 
     /// Map closure bounds to a `Span` that should be used for error reporting.
     closure_bounds_mapping:
-        FxHashMap<Location, FxHashMap<(RegionVid, RegionVid), (ConstraintCategory<'tcx>, Span)>>,
+        FxHashMap<Location, FxHashMap<(RegionVid, RegionVid), (ConstraintCategory, Span)>>,
 
     /// Map universe indexes to information on why we created it.
     universe_causes: FxHashMap<ty::UniverseIndex, UniverseInfo<'tcx>>,
@@ -267,7 +267,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         member_constraints_in: MemberConstraintSet<'tcx, RegionVid>,
         closure_bounds_mapping: FxHashMap<
             Location,
-            FxHashMap<(RegionVid, RegionVid), (ConstraintCategory<'tcx>, Span)>,
+            FxHashMap<(RegionVid, RegionVid), (ConstraintCategory, Span)>,
         >,
         universe_causes: FxHashMap<ty::UniverseIndex, UniverseInfo<'tcx>>,
         type_tests: Vec<TypeTest<'tcx>>,
@@ -1807,7 +1807,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
     pub(crate) fn retrieve_closure_constraint_info(
         &self,
         constraint: OutlivesConstraint<'tcx>,
-    ) -> Option<(ConstraintCategory<'tcx>, Span)> {
+    ) -> Option<(ConstraintCategory, Span)> {
         match constraint.locations {
             Locations::All(_) => None,
             Locations::Single(loc) => {
@@ -1822,7 +1822,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         fr1: RegionVid,
         fr1_origin: NllRegionVariableOrigin,
         fr2: RegionVid,
-    ) -> (ConstraintCategory<'tcx>, ObligationCause<'tcx>) {
+    ) -> (ConstraintCategory, ObligationCause<'tcx>) {
         let BlameConstraint { category, cause, .. } = self
             .best_blame_constraint(fr1, fr1_origin, |r| self.provides_universal_region(r, fr1, fr2))
             .0;
@@ -2362,7 +2362,7 @@ impl<'tcx> ClosureRegionRequirementsExt<'tcx> for ClosureRegionRequirements<'tcx
 
 #[derive(Clone, Debug)]
 pub struct BlameConstraint<'tcx> {
-    pub category: ConstraintCategory<'tcx>,
+    pub category: ConstraintCategory,
     pub from_closure: bool,
     pub cause: ObligationCause<'tcx>,
     pub variance_info: ty::VarianceDiagInfo<'tcx>,

compiler/rustc_borrowck/src/type_check/canonical.rs

@@ -28,7 +28,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
     pub(super) fn fully_perform_op<R: fmt::Debug, Op>(
         &mut self,
         locations: Locations,
-        category: ConstraintCategory<'tcx>,
+        category: ConstraintCategory,
         op: Op,
     ) -> Fallible<R>
     where
@@ -85,7 +85,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         &mut self,
         trait_ref: ty::TraitRef<'tcx>,
         locations: Locations,
-        category: ConstraintCategory<'tcx>,
+        category: ConstraintCategory,
     ) {
         self.prove_predicate(
             ty::Binder::dummy(ty::PredicateKind::Trait(ty::TraitPredicate {
@@ -124,7 +124,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         &mut self,
         predicates: impl IntoIterator<Item = impl ToPredicate<'tcx>>,
         locations: Locations,
-        category: ConstraintCategory<'tcx>,
+        category: ConstraintCategory,
     ) {
         for predicate in predicates {
             let predicate = predicate.to_predicate(self.tcx());
@@ -139,7 +139,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         &mut self,
         predicate: ty::Predicate<'tcx>,
         locations: Locations,
-        category: ConstraintCategory<'tcx>,
+        category: ConstraintCategory,
     ) {
         let param_env = self.param_env;
         self.fully_perform_op(
@@ -164,7 +164,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         &mut self,
         value: T,
         location: impl NormalizeLocation,
-        category: ConstraintCategory<'tcx>,
+        category: ConstraintCategory,
     ) -> T
     where
         T: type_op::normalize::Normalizable<'tcx> + fmt::Display + Copy + 'tcx,

compiler/rustc_borrowck/src/type_check/constraint_conversion.rs

@@ -37,7 +37,7 @@ pub(crate) struct ConstraintConversion<'a, 'tcx> {
     param_env: ty::ParamEnv<'tcx>,
     locations: Locations,
     span: Span,
-    category: ConstraintCategory<'tcx>,
+    category: ConstraintCategory,
     constraints: &'a mut MirTypeckRegionConstraints<'tcx>,
 }
 
@@ -50,7 +50,7 @@ impl<'a, 'tcx> ConstraintConversion<'a, 'tcx> {
         param_env: ty::ParamEnv<'tcx>,
         locations: Locations,
         span: Span,
-        category: ConstraintCategory<'tcx>,
+        category: ConstraintCategory,
         constraints: &'a mut MirTypeckRegionConstraints<'tcx>,
     ) -> Self {
         Self {
@@ -175,7 +175,7 @@ impl<'a, 'tcx> ConstraintConversion<'a, 'tcx> {
         &mut self,
         sup: ty::RegionVid,
         sub: ty::RegionVid,
-        category: ConstraintCategory<'tcx>,
+        category: ConstraintCategory,
     ) {
         let category = match self.category {
             ConstraintCategory::Boring | ConstraintCategory::BoringNoLocation => category,
@@ -203,7 +203,7 @@ impl<'a, 'b, 'tcx> TypeOutlivesDelegate<'tcx> for &'a mut ConstraintConversion<'
         _origin: SubregionOrigin<'tcx>,
         a: ty::Region<'tcx>,
         b: ty::Region<'tcx>,
-        constraint_category: ConstraintCategory<'tcx>,
+        constraint_category: ConstraintCategory,
     ) {
         let b = self.to_region_vid(b);
         let a = self.to_region_vid(a);