Rollup merge of rust-lang#109166 - lcnr:define_opaque_types-explicit,…

… r=oli-obk

make `define_opaque_types` fully explicit

based on the idea of rust-lang#108389. Moved `define_opaque_types` into the actual operations, e.g. `eq`, instead of `infcx.at` because normalization doesn't use `define_opaque_types` and even creates it's own `At` with a different `define_opaque_types` internally.

Somewhat surprisingly, coherence actually relies on `DefineOpaqueTypes::Yes` for soundness which was revealed because I've incorrectly used `DefineOpaqueTypes::No` in `equate_impl_headers`. It feels concerning that even though this is the case, we still sometimes use `DefineOpaqueTypes::No` in coherence. I did not look into this as part of this PR as it is purely changing the structure of the code without changing behavior in any way.

r? `@oli-obk`

compiler/rustc_hir_analysis/src/coherence/builtin.rs

@@ -9,8 +9,8 @@ use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::lang_items::LangItem;
 use rustc_hir::ItemKind;
 use rustc_infer::infer::outlives::env::OutlivesEnvironment;
-use rustc_infer::infer::TyCtxtInferExt;
 use rustc_infer::infer::{self, RegionResolutionError};
+use rustc_infer::infer::{DefineOpaqueTypes, TyCtxtInferExt};
 use rustc_middle::ty::adjustment::CoerceUnsizedInfo;
 use rustc_middle::ty::{self, suggest_constraining_type_params, Ty, TyCtxt, TypeVisitableExt};
 use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt;
@@ -235,7 +235,8 @@ fn visit_implementation_of_dispatch_from_dyn(tcx: TyCtxt<'_>, impl_did: LocalDef
     use rustc_type_ir::sty::TyKind::*;
     match (source.kind(), target.kind()) {
         (&Ref(r_a, _, mutbl_a), Ref(r_b, _, mutbl_b))
-            if infcx.at(&cause, param_env).eq(r_a, *r_b).is_ok() && mutbl_a == *mutbl_b => {}
+            if infcx.at(&cause, param_env).eq(DefineOpaqueTypes::No, r_a, *r_b).is_ok()
+                && mutbl_a == *mutbl_b => {}
         (&RawPtr(tm_a), &RawPtr(tm_b)) if tm_a.mutbl == tm_b.mutbl => (),
         (&Adt(def_a, substs_a), &Adt(def_b, substs_b))
             if def_a.is_struct() && def_b.is_struct() =>
@@ -278,7 +279,9 @@ fn visit_implementation_of_dispatch_from_dyn(tcx: TyCtxt<'_>, impl_did: LocalDef
                         }
                     }
 
-                    if let Ok(ok) = infcx.at(&cause, param_env).eq(ty_a, ty_b) {
+                    if let Ok(ok) =
+                        infcx.at(&cause, param_env).eq(DefineOpaqueTypes::No, ty_a, ty_b)
+                    {
                         if ok.obligations.is_empty() {
                             create_err(
                                 "the trait `DispatchFromDyn` may only be implemented \
@@ -504,7 +507,7 @@ pub fn coerce_unsized_info<'tcx>(tcx: TyCtxt<'tcx>, impl_did: DefId) -> CoerceUn
                     // we may have to evaluate constraint
                     // expressions in the course of execution.)
                     // See e.g., #41936.
-                    if let Ok(ok) = infcx.at(&cause, param_env).eq(a, b) {
+                    if let Ok(ok) = infcx.at(&cause, param_env).eq(DefineOpaqueTypes::No, a, b) {
                         if ok.obligations.is_empty() {
                             return None;
                         }

compiler/rustc_hir_analysis/src/lib.rs

@@ -102,7 +102,7 @@ use rustc_errors::ErrorGuaranteed;
 use rustc_errors::{DiagnosticMessage, SubdiagnosticMessage};
 use rustc_hir as hir;
 use rustc_hir::Node;
-use rustc_infer::infer::{InferOk, TyCtxtInferExt};
+use rustc_infer::infer::{DefineOpaqueTypes, InferOk, TyCtxtInferExt};
 use rustc_macros::fluent_messages;
 use rustc_middle::middle;
 use rustc_middle::ty::query::Providers;
@@ -165,7 +165,7 @@ fn require_same_types<'tcx>(
 ) -> bool {
     let infcx = &tcx.infer_ctxt().build();
     let param_env = ty::ParamEnv::empty();
-    let errors = match infcx.at(cause, param_env).eq(expected, actual) {
+    let errors = match infcx.at(cause, param_env).eq(DefineOpaqueTypes::No, expected, actual) {
         Ok(InferOk { obligations, .. }) => traits::fully_solve_obligations(infcx, obligations),
         Err(err) => {
             infcx.err_ctxt().report_mismatched_types(cause, expected, actual, err).emit();

compiler/rustc_hir_typeck/src/closure.rs

@@ -8,7 +8,7 @@ use rustc_hir as hir;
 use rustc_hir::lang_items::LangItem;
 use rustc_hir_analysis::astconv::AstConv;
 use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
-use rustc_infer::infer::LateBoundRegionConversionTime;
+use rustc_infer::infer::{DefineOpaqueTypes, LateBoundRegionConversionTime};
 use rustc_infer::infer::{InferOk, InferResult};
 use rustc_macros::{TypeFoldable, TypeVisitable};
 use rustc_middle::ty::subst::InternalSubsts;
@@ -563,10 +563,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             ) {
                 // Check that E' = S'.
                 let cause = self.misc(hir_ty.span);
-                let InferOk { value: (), obligations } = self
-                    .at(&cause, self.param_env)
-                    .define_opaque_types(true)
-                    .eq(*expected_ty, supplied_ty)?;
+                let InferOk { value: (), obligations } = self.at(&cause, self.param_env).eq(
+                    DefineOpaqueTypes::Yes,
+                    *expected_ty,
+                    supplied_ty,
+                )?;
                 all_obligations.extend(obligations);
             }
 
@@ -576,10 +577,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 supplied_sig.output(),
             );
             let cause = &self.misc(decl.output.span());
-            let InferOk { value: (), obligations } = self
-                .at(cause, self.param_env)
-                .define_opaque_types(true)
-                .eq(expected_sigs.liberated_sig.output(), supplied_output_ty)?;
+            let InferOk { value: (), obligations } = self.at(cause, self.param_env).eq(
+                DefineOpaqueTypes::Yes,
+                expected_sigs.liberated_sig.output(),
+                supplied_output_ty,
+            )?;
             all_obligations.extend(obligations);
 
             let inputs = inputs.into_iter().map(|ty| self.resolve_vars_if_possible(ty));

compiler/rustc_hir_typeck/src/coercion.rs

@@ -45,7 +45,7 @@ use rustc_hir::intravisit::{self, Visitor};
 use rustc_hir::Expr;
 use rustc_hir_analysis::astconv::AstConv;
 use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
-use rustc_infer::infer::{Coercion, InferOk, InferResult};
+use rustc_infer::infer::{Coercion, DefineOpaqueTypes, InferOk, InferResult};
 use rustc_infer::traits::Obligation;
 use rustc_middle::lint::in_external_macro;
 use rustc_middle::ty::adjustment::{
@@ -143,11 +143,11 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
     fn unify(&self, a: Ty<'tcx>, b: Ty<'tcx>) -> InferResult<'tcx, Ty<'tcx>> {
         debug!("unify(a: {:?}, b: {:?}, use_lub: {})", a, b, self.use_lub);
         self.commit_if_ok(|_| {
-            let at = self.at(&self.cause, self.fcx.param_env).define_opaque_types(true);
+            let at = self.at(&self.cause, self.fcx.param_env);
             if self.use_lub {
-                at.lub(b, a)
+                at.lub(DefineOpaqueTypes::Yes, b, a)
             } else {
-                at.sup(b, a)
+                at.sup(DefineOpaqueTypes::Yes, b, a)
                     .map(|InferOk { value: (), obligations }| InferOk { value: a, obligations })
             }
         })
@@ -175,7 +175,7 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
             // so this will have the side-effect of making sure we have no ambiguities
             // due to `[type error]` and `_` not coercing together.
             let _ = self.commit_if_ok(|_| {
-                self.at(&self.cause, self.param_env).define_opaque_types(true).eq(a, b)
+                self.at(&self.cause, self.param_env).eq(DefineOpaqueTypes::Yes, a, b)
             });
             return success(vec![], self.fcx.tcx.ty_error(guar), vec![]);
         }
@@ -1101,9 +1101,13 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     (ty::FnDef(..), ty::FnDef(..)) => {
                         // Don't reify if the function types have a LUB, i.e., they
                         // are the same function and their parameters have a LUB.
-                        match self
-                            .commit_if_ok(|_| self.at(cause, self.param_env).lub(prev_ty, new_ty))
-                        {
+                        match self.commit_if_ok(|_| {
+                            self.at(cause, self.param_env).lub(
+                                DefineOpaqueTypes::No,
+                                prev_ty,
+                                new_ty,
+                            )
+                        }) {
                             // We have a LUB of prev_ty and new_ty, just return it.
                             Ok(ok) => return Ok(self.register_infer_ok_obligations(ok)),
                             Err(_) => {
@@ -1153,7 +1157,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             let sig = self
                 .at(cause, self.param_env)
                 .trace(prev_ty, new_ty)
-                .lub(a_sig, b_sig)
+                .lub(DefineOpaqueTypes::No, a_sig, b_sig)
                 .map(|ok| self.register_infer_ok_obligations(ok))?;
 
             // Reify both sides and return the reified fn pointer type.
@@ -1237,7 +1241,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 );
 
                 return self
-                    .commit_if_ok(|_| self.at(cause, self.param_env).lub(prev_ty, new_ty))
+                    .commit_if_ok(|_| {
+                        self.at(cause, self.param_env).lub(DefineOpaqueTypes::No, prev_ty, new_ty)
+                    })
                     .map(|ok| self.register_infer_ok_obligations(ok));
             }
         }
@@ -1248,8 +1254,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 if let Some(e) = first_error {
                     Err(e)
                 } else {
-                    self.commit_if_ok(|_| self.at(cause, self.param_env).lub(prev_ty, new_ty))
-                        .map(|ok| self.register_infer_ok_obligations(ok))
+                    self.commit_if_ok(|_| {
+                        self.at(cause, self.param_env).lub(DefineOpaqueTypes::No, prev_ty, new_ty)
+                    })
+                    .map(|ok| self.register_infer_ok_obligations(ok))
                 }
             }
             Ok(ok) => {
@@ -1487,8 +1495,12 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> {
             assert!(expression_ty.is_unit(), "if let hack without unit type");
             fcx.at(cause, fcx.param_env)
                 // needed for tests/ui/type-alias-impl-trait/issue-65679-inst-opaque-ty-from-val-twice.rs
-                .define_opaque_types(true)
-                .eq_exp(label_expression_as_expected, expression_ty, self.merged_ty())
+                .eq_exp(
+                    DefineOpaqueTypes::Yes,
+                    label_expression_as_expected,
+                    expression_ty,
+                    self.merged_ty(),
+                )
                 .map(|infer_ok| {
                     fcx.register_infer_ok_obligations(infer_ok);
                     expression_ty

compiler/rustc_hir_typeck/src/demand.rs

@@ -8,7 +8,7 @@ use rustc_hir::def::CtorKind;
 use rustc_hir::intravisit::Visitor;
 use rustc_hir::lang_items::LangItem;
 use rustc_hir::{is_range_literal, Node};
-use rustc_infer::infer::InferOk;
+use rustc_infer::infer::{DefineOpaqueTypes, InferOk};
 use rustc_middle::lint::in_external_macro;
 use rustc_middle::middle::stability::EvalResult;
 use rustc_middle::ty::adjustment::AllowTwoPhase;
@@ -113,7 +113,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         expected: Ty<'tcx>,
         actual: Ty<'tcx>,
     ) -> Option<DiagnosticBuilder<'tcx, ErrorGuaranteed>> {
-        match self.at(cause, self.param_env).define_opaque_types(true).sup(expected, actual) {
+        match self.at(cause, self.param_env).sup(DefineOpaqueTypes::Yes, expected, actual) {
             Ok(InferOk { obligations, value: () }) => {
                 self.register_predicates(obligations);
                 None
@@ -143,7 +143,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         expected: Ty<'tcx>,
         actual: Ty<'tcx>,
     ) -> Option<DiagnosticBuilder<'tcx, ErrorGuaranteed>> {
-        match self.at(cause, self.param_env).define_opaque_types(true).eq(expected, actual) {
+        match self.at(cause, self.param_env).eq(DefineOpaqueTypes::Yes, expected, actual) {
             Ok(InferOk { obligations, value: () }) => {
                 self.register_predicates(obligations);
                 None

compiler/rustc_hir_typeck/src/expr.rs

@@ -36,6 +36,7 @@ use rustc_hir_analysis::astconv::AstConv as _;
 use rustc_hir_analysis::check::ty_kind_suggestion;
 use rustc_infer::infer;
 use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
+use rustc_infer::infer::DefineOpaqueTypes;
 use rustc_infer::infer::InferOk;
 use rustc_infer::traits::ObligationCause;
 use rustc_middle::middle::stability;
@@ -1683,7 +1684,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                             if let Some(_) = remaining_fields.remove(&ident) {
                                 let target_ty = self.field_ty(base_expr.span, f, substs);
                                 let cause = self.misc(base_expr.span);
-                                match self.at(&cause, self.param_env).sup(target_ty, fru_ty) {
+                                match self.at(&cause, self.param_env).sup(
+                                    DefineOpaqueTypes::No,
+                                    target_ty,
+                                    fru_ty,
+                                ) {
                                     Ok(InferOk { obligations, value: () }) => {
                                         self.register_predicates(obligations)
                                     }

compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs

@@ -19,7 +19,7 @@ use rustc_hir_analysis::astconv::{
 };
 use rustc_infer::infer::canonical::{Canonical, OriginalQueryValues, QueryResponse};
 use rustc_infer::infer::error_reporting::TypeAnnotationNeeded::E0282;
-use rustc_infer::infer::InferResult;
+use rustc_infer::infer::{DefineOpaqueTypes, InferResult};
 use rustc_middle::ty::adjustment::{Adjust, Adjustment, AutoBorrow, AutoBorrowMutability};
 use rustc_middle::ty::error::TypeError;
 use rustc_middle::ty::fold::TypeFoldable;
@@ -558,7 +558,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             let span = self.tcx.hir().body(body_id).value.span;
             let ok = self
                 .at(&self.misc(span), self.param_env)
-                .eq(interior, witness)
+                .eq(DefineOpaqueTypes::No, interior, witness)
                 .expect("Failed to unify generator interior type");
             let mut obligations = ok.obligations;
 
@@ -1341,7 +1341,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             // This also occurs for an enum variant on a type alias.
             let impl_ty = self.normalize(span, tcx.type_of(impl_def_id).subst(tcx, substs));
             let self_ty = self.normalize(span, self_ty);
-            match self.at(&self.misc(span), self.param_env).eq(impl_ty, self_ty) {
+            match self.at(&self.misc(span), self.param_env).eq(
+                DefineOpaqueTypes::No,
+                impl_ty,
+                self_ty,
+            ) {
                 Ok(ok) => self.register_infer_ok_obligations(ok),
                 Err(_) => {
                     self.tcx.sess.delay_span_bug(

compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs

@@ -24,8 +24,8 @@ use rustc_hir_analysis::structured_errors::StructuredDiagnostic;
 use rustc_index::vec::IndexVec;
 use rustc_infer::infer::error_reporting::{FailureCode, ObligationCauseExt};
 use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
-use rustc_infer::infer::InferOk;
 use rustc_infer::infer::TypeTrace;
+use rustc_infer::infer::{DefineOpaqueTypes, InferOk};
 use rustc_middle::ty::adjustment::AllowTwoPhase;
 use rustc_middle::ty::visit::TypeVisitableExt;
 use rustc_middle::ty::{self, IsSuggestable, Ty};
@@ -301,9 +301,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
             // 3. Check if the formal type is a supertype of the checked one
             //    and register any such obligations for future type checks
-            let supertype_error = self
-                .at(&self.misc(provided_arg.span), self.param_env)
-                .sup(formal_input_ty, coerced_ty);
+            let supertype_error = self.at(&self.misc(provided_arg.span), self.param_env).sup(
+                DefineOpaqueTypes::No,
+                formal_input_ty,
+                coerced_ty,
+            );
             let subtyping_error = match supertype_error {
                 Ok(InferOk { obligations, value: () }) => {
                     self.register_predicates(obligations);
@@ -585,7 +587,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
             // Using probe here, since we don't want this subtyping to affect inference.
             let subtyping_error = self.probe(|_| {
-                self.at(&self.misc(arg_span), self.param_env).sup(formal_input_ty, coerced_ty).err()
+                self.at(&self.misc(arg_span), self.param_env)
+                    .sup(DefineOpaqueTypes::No, formal_input_ty, coerced_ty)
+                    .err()
             });
 
             // Same as above: if either the coerce type or the checked type is an error type,

compiler/rustc_hir_typeck/src/generator_interior/mod.rs

@@ -13,7 +13,7 @@ use rustc_hir::def_id::DefId;
 use rustc_hir::hir_id::HirIdSet;
 use rustc_hir::intravisit::{self, Visitor};
 use rustc_hir::{Arm, Expr, ExprKind, Guard, HirId, Pat, PatKind};
-use rustc_infer::infer::RegionVariableOrigin;
+use rustc_infer::infer::{DefineOpaqueTypes, RegionVariableOrigin};
 use rustc_middle::middle::region::{self, Scope, ScopeData, YieldData};
 use rustc_middle::ty::fold::FnMutDelegate;
 use rustc_middle::ty::{self, BoundVariableKind, RvalueScopes, Ty, TyCtxt, TypeVisitableExt};
@@ -327,7 +327,11 @@ pub fn resolve_interior<'a, 'tcx>(
     );
 
     // Unify the type variable inside the generator with the new witness
-    match fcx.at(&fcx.misc(body.value.span), fcx.param_env).eq(interior, witness) {
+    match fcx.at(&fcx.misc(body.value.span), fcx.param_env).eq(
+        DefineOpaqueTypes::No,
+        interior,
+        witness,
+    ) {
         Ok(ok) => fcx.register_infer_ok_obligations(ok),
         _ => bug!("failed to relate {interior} and {witness}"),
     }

compiler/rustc_hir_typeck/src/method/confirm.rs

@@ -8,7 +8,7 @@ use rustc_hir_analysis::astconv::generics::{
     check_generic_arg_count_for_call, create_substs_for_generic_args,
 };
 use rustc_hir_analysis::astconv::{AstConv, CreateSubstsForGenericArgsCtxt, IsMethodCall};
-use rustc_infer::infer::{self, InferOk};
+use rustc_infer::infer::{self, DefineOpaqueTypes, InferOk};
 use rustc_middle::traits::{ObligationCauseCode, UnifyReceiverContext};
 use rustc_middle::ty::adjustment::{Adjust, Adjustment, PointerCast};
 use rustc_middle::ty::adjustment::{AllowTwoPhase, AutoBorrow, AutoBorrowMutability};
@@ -478,7 +478,7 @@ impl<'a, 'tcx> ConfirmContext<'a, 'tcx> {
                 substs,
             })),
         );
-        match self.at(&cause, self.param_env).sup(method_self_ty, self_ty) {
+        match self.at(&cause, self.param_env).sup(DefineOpaqueTypes::No, method_self_ty, self_ty) {
             Ok(InferOk { obligations, value: () }) => {
                 self.register_predicates(obligations);
             }