Rollup merge of #111246 - lcnr:no-escaping-bound-vars, r=compiler-errors

forbid escaping bound vars in combine

removes the `CollectAllMismatches` in favor of a slightly more manual approach.

r? types cc ``@estebank``

compiler/rustc_infer/src/infer/combine.rs

@@ -73,6 +73,8 @@ impl<'tcx> InferCtxt<'tcx> {
         R: ObligationEmittingRelation<'tcx>,
     {
         let a_is_expected = relation.a_is_expected();
+        debug_assert!(!a.has_escaping_bound_vars());
+        debug_assert!(!b.has_escaping_bound_vars());
 
         match (a.kind(), b.kind()) {
             // Relate integral variables to other types
@@ -163,6 +165,8 @@ impl<'tcx> InferCtxt<'tcx> {
         R: ObligationEmittingRelation<'tcx>,
     {
         debug!("{}.consts({:?}, {:?})", relation.tag(), a, b);
+        debug_assert!(!a.has_escaping_bound_vars());
+        debug_assert!(!b.has_escaping_bound_vars());
         if a == b {
             return Ok(a);
         }
@@ -238,22 +242,12 @@ impl<'tcx> InferCtxt<'tcx> {
             (_, ty::ConstKind::Infer(InferConst::Var(vid))) => {
                 return self.unify_const_variable(vid, a);
             }
-            (ty::ConstKind::Unevaluated(..), _) if self.tcx.lazy_normalization() => {
+            (ty::ConstKind::Unevaluated(..), _) | (_, ty::ConstKind::Unevaluated(..))
-                // FIXME(#59490): Need to remove the leak check to accommodate
+                if self.tcx.lazy_normalization() =>
-                // escaping bound variables here.
+            {
-                if !a.has_escaping_bound_vars() && !b.has_escaping_bound_vars() {
+                relation.register_const_equate_obligation(a, b);
-                    relation.register_const_equate_obligation(a, b);
-                }
                 return Ok(b);
             }
-            (_, ty::ConstKind::Unevaluated(..)) if self.tcx.lazy_normalization() => {
-                // FIXME(#59490): Need to remove the leak check to accommodate
-                // escaping bound variables here.
-                if !a.has_escaping_bound_vars() && !b.has_escaping_bound_vars() {
-                    relation.register_const_equate_obligation(a, b);
-                }
-                return Ok(a);
-            }
             _ => {}
         }
 

compiler/rustc_trait_selection/src/traits/error_reporting/method_chain.rs

@@ -1,102 +0,0 @@
-use crate::infer::InferCtxt;
-
-use rustc_infer::infer::ObligationEmittingRelation;
-use rustc_infer::traits::PredicateObligations;
-use rustc_middle::ty::error::TypeError;
-use rustc_middle::ty::relate::{self, Relate, RelateResult, TypeRelation};
-use rustc_middle::ty::{self, Ty, TyCtxt};
-
-pub struct CollectAllMismatches<'a, 'tcx> {
-    pub infcx: &'a InferCtxt<'tcx>,
-    pub param_env: ty::ParamEnv<'tcx>,
-    pub errors: Vec<TypeError<'tcx>>,
-}
-
-impl<'a, 'tcx> TypeRelation<'tcx> for CollectAllMismatches<'a, 'tcx> {
-    fn tag(&self) -> &'static str {
-        "CollectAllMismatches"
-    }
-
-    fn tcx(&self) -> TyCtxt<'tcx> {
-        self.infcx.tcx
-    }
-
-    fn param_env(&self) -> ty::ParamEnv<'tcx> {
-        self.param_env
-    }
-
-    fn a_is_expected(&self) -> bool {
-        true
-    }
-
-    fn relate_with_variance<T: Relate<'tcx>>(
-        &mut self,
-        _: ty::Variance,
-        _: ty::VarianceDiagInfo<'tcx>,
-        a: T,
-        b: T,
-    ) -> RelateResult<'tcx, T> {
-        self.relate(a, b)
-    }
-
-    fn regions(
-        &mut self,
-        a: ty::Region<'tcx>,
-        _b: ty::Region<'tcx>,
-    ) -> RelateResult<'tcx, ty::Region<'tcx>> {
-        Ok(a)
-    }
-
-    fn tys(&mut self, a: Ty<'tcx>, b: Ty<'tcx>) -> RelateResult<'tcx, Ty<'tcx>> {
-        self.infcx.probe(|_| {
-            if a.is_ty_var() || b.is_ty_var() {
-                Ok(a)
-            } else {
-                self.infcx.super_combine_tys(self, a, b).or_else(|e| {
-                    self.errors.push(e);
-                    Ok(a)
-                })
-            }
-        })
-    }
-
-    fn consts(
-        &mut self,
-        a: ty::Const<'tcx>,
-        b: ty::Const<'tcx>,
-    ) -> RelateResult<'tcx, ty::Const<'tcx>> {
-        self.infcx.probe(|_| {
-            if a.is_ct_infer() || b.is_ct_infer() {
-                Ok(a)
-            } else {
-                relate::super_relate_consts(self, a, b) // could do something similar here for constants!
-            }
-        })
-    }
-
-    fn binders<T: Relate<'tcx>>(
-        &mut self,
-        a: ty::Binder<'tcx, T>,
-        b: ty::Binder<'tcx, T>,
-    ) -> RelateResult<'tcx, ty::Binder<'tcx, T>> {
-        Ok(a.rebind(self.relate(a.skip_binder(), b.skip_binder())?))
-    }
-}
-
-impl<'tcx> ObligationEmittingRelation<'tcx> for CollectAllMismatches<'_, 'tcx> {
-    fn alias_relate_direction(&self) -> ty::AliasRelationDirection {
-        // FIXME(deferred_projection_equality): We really should get rid of this relation.
-        ty::AliasRelationDirection::Equate
-    }
-
-    fn register_obligations(&mut self, _obligations: PredicateObligations<'tcx>) {
-        // FIXME(deferred_projection_equality)
-    }
-
-    fn register_predicates(
-        &mut self,
-        _obligations: impl IntoIterator<Item: ty::ToPredicate<'tcx>>,
-    ) {
-        // FIXME(deferred_projection_equality)
-    }
-}

compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs

@@ -1,5 +1,4 @@
 mod ambiguity;
-pub mod method_chain;
 pub mod on_unimplemented;
 pub mod suggestions;
 
@@ -559,6 +558,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
             suggest_increasing_limit,
             |err| {
                 self.note_obligation_cause_code(
+                    obligation.cause.body_id,
                     err,
                     predicate,
                     obligation.param_env,
@@ -1431,6 +1431,7 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                 | ObligationCauseCode::ExprItemObligation(..) = code
                 {
                     self.note_obligation_cause_code(
+                        error.obligation.cause.body_id,
                         &mut diag,
                         error.obligation.predicate,
                         error.obligation.param_env,
@@ -2544,6 +2545,7 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
         // message, and fall back to regular note otherwise.
         if !self.maybe_note_obligation_cause_for_async_await(err, obligation) {
             self.note_obligation_cause_code(
+                obligation.cause.body_id,
                 err,
                 obligation.predicate,
                 obligation.param_env,

compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs

@@ -25,10 +25,9 @@ use rustc_hir::{AsyncGeneratorKind, GeneratorKind, Node};
 use rustc_hir::{Expr, HirId};
 use rustc_infer::infer::error_reporting::TypeErrCtxt;
 use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
-use rustc_infer::infer::{InferOk, LateBoundRegionConversionTime};
+use rustc_infer::infer::{DefineOpaqueTypes, InferOk, LateBoundRegionConversionTime};
 use rustc_middle::hir::map;
 use rustc_middle::ty::error::TypeError::{self, Sorts};
-use rustc_middle::ty::relate::TypeRelation;
 use rustc_middle::ty::{
     self, suggest_arbitrary_trait_bound, suggest_constraining_type_param, AdtKind,
     GeneratorDiagnosticData, GeneratorInteriorTypeCause, Infer, InferTy, InternalSubsts,
@@ -39,9 +38,9 @@ use rustc_span::def_id::LocalDefId;
 use rustc_span::symbol::{sym, Ident, Symbol};
 use rustc_span::{BytePos, DesugaringKind, ExpnKind, MacroKind, Span, DUMMY_SP};
 use rustc_target::spec::abi;
+use std::iter;
 use std::ops::Deref;
 
-use super::method_chain::CollectAllMismatches;
 use super::InferCtxtPrivExt;
 use crate::infer::InferCtxtExt as _;
 use crate::traits::query::evaluate_obligation::InferCtxtExt as _;
@@ -319,6 +318,7 @@ pub trait TypeErrCtxtExt<'tcx> {
 
     fn note_obligation_cause_code<T>(
         &self,
+        body_id: LocalDefId,
         err: &mut Diagnostic,
         predicate: T,
         param_env: ty::ParamEnv<'tcx>,
@@ -359,8 +359,9 @@ pub trait TypeErrCtxtExt<'tcx> {
     );
     fn note_function_argument_obligation(
         &self,
-        arg_hir_id: HirId,
+        body_id: LocalDefId,
         err: &mut Diagnostic,
+        arg_hir_id: HirId,
         parent_code: &ObligationCauseCode<'tcx>,
         param_env: ty::ParamEnv<'tcx>,
         predicate: ty::Predicate<'tcx>,
@@ -2742,6 +2743,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
         // bound that introduced the obligation (e.g. `T: Send`).
         debug!(?next_code);
         self.note_obligation_cause_code(
+            obligation.cause.body_id,
             err,
             obligation.predicate,
             obligation.param_env,
@@ -2753,6 +2755,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
 
     fn note_obligation_cause_code<T>(
         &self,
+        body_id: LocalDefId,
         err: &mut Diagnostic,
         predicate: T,
         param_env: ty::ParamEnv<'tcx>,
@@ -3152,6 +3155,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                     // #74711: avoid a stack overflow
                     ensure_sufficient_stack(|| {
                         self.note_obligation_cause_code(
+                            body_id,
                             err,
                             parent_predicate,
                             param_env,
@@ -3163,6 +3167,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                 } else {
                     ensure_sufficient_stack(|| {
                         self.note_obligation_cause_code(
+                            body_id,
                             err,
                             parent_predicate,
                             param_env,
@@ -3292,6 +3297,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                 // #74711: avoid a stack overflow
                 ensure_sufficient_stack(|| {
                     self.note_obligation_cause_code(
+                        body_id,
                         err,
                         parent_predicate,
                         param_env,
@@ -3307,6 +3313,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                 // #74711: avoid a stack overflow
                 ensure_sufficient_stack(|| {
                     self.note_obligation_cause_code(
+                        body_id,
                         err,
                         parent_predicate,
                         param_env,
@@ -3323,8 +3330,9 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                 ..
             } => {
                 self.note_function_argument_obligation(
-                    arg_hir_id,
+                    body_id,
                     err,
+                    arg_hir_id,
                     parent_code,
                     param_env,
                     predicate,
@@ -3332,6 +3340,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                 );
                 ensure_sufficient_stack(|| {
                     self.note_obligation_cause_code(
+                        body_id,
                         err,
                         predicate,
                         param_env,
@@ -3553,8 +3562,9 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
     }
     fn note_function_argument_obligation(
         &self,
-        arg_hir_id: HirId,
+        body_id: LocalDefId,
         err: &mut Diagnostic,
+        arg_hir_id: HirId,
         parent_code: &ObligationCauseCode<'tcx>,
         param_env: ty::ParamEnv<'tcx>,
         failed_pred: ty::Predicate<'tcx>,
@@ -3587,7 +3597,6 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
             // to an associated type (as seen from `trait_pred`) in the predicate. Like in
             // trait_pred `S: Sum<<Self as Iterator>::Item>` and predicate `i32: Sum<&()>`
             let mut type_diffs = vec![];
-
             if let ObligationCauseCode::ExprBindingObligation(def_id, _, _, idx) = parent_code.deref()
                 && let Some(node_substs) = typeck_results.node_substs_opt(call_hir_id)
                 && let where_clauses = self.tcx.predicates_of(def_id).instantiate(self.tcx, node_substs)
@@ -3596,14 +3605,26 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                 if let Some(where_pred) = where_pred.to_opt_poly_trait_pred()
                     && let Some(failed_pred) = failed_pred.to_opt_poly_trait_pred()
                 {
-                    let mut c = CollectAllMismatches {
+                    let where_pred = self.instantiate_binder_with_placeholders(where_pred);
-                        infcx: self.infcx,
+                    let failed_pred = self.instantiate_binder_with_fresh_vars(
-                        param_env,
+                        expr.span,
-                        errors: vec![],
+                        LateBoundRegionConversionTime::FnCall,
+                        failed_pred
+                    );
+
+                    let zipped =
+                        iter::zip(where_pred.trait_ref.substs, failed_pred.trait_ref.substs);
+                    for (expected, actual) in zipped {
+                        self.probe(|_| {
+                            match self
+                                .at(&ObligationCause::misc(expr.span, body_id), param_env)
+                                .eq(DefineOpaqueTypes::No, expected, actual)
+                            {
+                                Ok(_) => (), // We ignore nested obligations here for now.
+                                Err(err) => type_diffs.push(err),
+                            }
+                        })
                     };
-                    if let Ok(_) = c.relate(where_pred, failed_pred) {
-                        type_diffs = c.errors;
-                    }
                 } else if let Some(where_pred) = where_pred.to_opt_poly_projection_pred()
                     && let Some(failed_pred) = failed_pred.to_opt_poly_projection_pred()
                     && let Some(found) = failed_pred.skip_binder().term.ty()