Rollup merge of #132344 - compiler-errors:same-thing, r=lcnr

Merge `HostPolarity` and `BoundConstness`

They're basically the same thing, and I think `BoundConstness` is easier to use.

r? fee1-dead or reassign

compiler/rustc_hir_analysis/src/bounds.rs

@@ -84,11 +84,11 @@ impl<'tcx> Bounds<'tcx> {
         &mut self,
         tcx: TyCtxt<'tcx>,
         bound_trait_ref: ty::PolyTraitRef<'tcx>,
-        host: ty::HostPolarity,
+        constness: ty::BoundConstness,
         span: Span,
     ) {
         if tcx.is_const_trait(bound_trait_ref.def_id()) {
-            self.clauses.push((bound_trait_ref.to_host_effect_clause(tcx, host), span));
+            self.clauses.push((bound_trait_ref.to_host_effect_clause(tcx, constness), span));
         } else {
             tcx.dcx().span_delayed_bug(span, "tried to lower {host:?} bound for non-const trait");
         }

compiler/rustc_hir_analysis/src/check/compare_impl_item.rs

@@ -218,7 +218,7 @@ fn compare_method_predicate_entailment<'tcx>(
                     tcx.const_conditions(trait_m.def_id).instantiate_own(tcx, trait_to_impl_args),
                 )
                 .map(|(trait_ref, _)| {
-                    trait_ref.to_host_effect_clause(tcx, ty::HostPolarity::Maybe)
+                    trait_ref.to_host_effect_clause(tcx, ty::BoundConstness::Maybe)
                 }),
         );
     }
@@ -272,7 +272,7 @@ fn compare_method_predicate_entailment<'tcx>(
                 tcx,
                 cause,
                 param_env,
-                const_condition.to_host_effect_clause(tcx, ty::HostPolarity::Maybe),
+                const_condition.to_host_effect_clause(tcx, ty::BoundConstness::Maybe),
             ));
         }
     }
@@ -1942,7 +1942,7 @@ fn compare_type_predicate_entailment<'tcx>(
                     tcx.const_conditions(trait_ty.def_id).instantiate_own(tcx, trait_to_impl_args),
                 )
                 .map(|(trait_ref, _)| {
-                    trait_ref.to_host_effect_clause(tcx, ty::HostPolarity::Maybe)
+                    trait_ref.to_host_effect_clause(tcx, ty::BoundConstness::Maybe)
                 }),
         );
     }
@@ -1985,7 +1985,7 @@ fn compare_type_predicate_entailment<'tcx>(
                 tcx,
                 cause,
                 param_env,
-                const_condition.to_host_effect_clause(tcx, ty::HostPolarity::Maybe),
+                const_condition.to_host_effect_clause(tcx, ty::BoundConstness::Maybe),
             ));
         }
     }
@@ -2091,7 +2091,7 @@ pub(super) fn check_type_bounds<'tcx>(
                         tcx,
                         mk_cause(span),
                         param_env,
-                        c.to_host_effect_clause(tcx, ty::HostPolarity::Maybe),
+                        c.to_host_effect_clause(tcx, ty::BoundConstness::Maybe),
                     )
                 }),
         );

compiler/rustc_hir_analysis/src/check/wfcheck.rs

@@ -1388,7 +1388,7 @@ fn check_impl<'tcx>(
                                 ObligationCauseCode::WellFormed(None),
                             ),
                             wfcx.param_env,
-                            bound.to_host_effect_clause(tcx, ty::HostPolarity::Maybe),
+                            bound.to_host_effect_clause(tcx, ty::BoundConstness::Maybe),
                         ))
                     }
                 }

compiler/rustc_hir_analysis/src/collect/predicates_of.rs

@@ -709,7 +709,7 @@ pub(super) fn assert_only_contains_predicates_from<'tcx>(
                 match clause.kind().skip_binder() {
                     ty::ClauseKind::HostEffect(ty::HostEffectPredicate {
                         trait_ref: _,
-                        host: ty::HostPolarity::Maybe,
+                        constness: ty::BoundConstness::Maybe,
                     }) => {}
                     _ => {
                         bug!(
@@ -725,8 +725,8 @@ pub(super) fn assert_only_contains_predicates_from<'tcx>(
                 match clause.kind().skip_binder() {
                     ty::ClauseKind::HostEffect(pred) => {
                         assert_eq!(
-                            pred.host,
-                            ty::HostPolarity::Maybe,
+                            pred.constness,
+                            ty::BoundConstness::Maybe,
                             "expected `~const` predicate when computing `{filter:?}` \
                             implied bounds: {clause:?}",
                         );
@@ -936,7 +936,7 @@ pub(super) fn const_conditions<'tcx>(
         bounds.push_const_bound(
             tcx,
             ty::Binder::dummy(ty::TraitRef::identity(tcx, def_id.to_def_id())),
-            ty::HostPolarity::Maybe,
+            ty::BoundConstness::Maybe,
             DUMMY_SP,
         );
 
@@ -956,7 +956,7 @@ pub(super) fn const_conditions<'tcx>(
                 clause.kind().map_bound(|clause| match clause {
                     ty::ClauseKind::HostEffect(ty::HostEffectPredicate {
                         trait_ref,
-                        host: ty::HostPolarity::Maybe,
+                        constness: ty::BoundConstness::Maybe,
                     }) => trait_ref,
                     _ => bug!("converted {clause:?}"),
                 }),
@@ -994,7 +994,7 @@ pub(super) fn implied_const_bounds<'tcx>(
                 clause.kind().map_bound(|clause| match clause {
                     ty::ClauseKind::HostEffect(ty::HostEffectPredicate {
                         trait_ref,
-                        host: ty::HostPolarity::Maybe,
+                        constness: ty::BoundConstness::Maybe,
                     }) => trait_ref,
                     _ => bug!("converted {clause:?}"),
                 }),

compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs

@@ -721,7 +721,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                             bounds.push_const_bound(
                                 tcx,
                                 poly_trait_ref,
-                                ty::HostPolarity::Const,
+                                ty::BoundConstness::Const,
                                 span,
                             );
                         }
@@ -744,7 +744,12 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
             PredicateFilter::ConstIfConst | PredicateFilter::SelfConstIfConst => match constness {
                 hir::BoundConstness::Maybe(span) => {
                     if polarity == ty::PredicatePolarity::Positive {
-                        bounds.push_const_bound(tcx, poly_trait_ref, ty::HostPolarity::Maybe, span);
+                        bounds.push_const_bound(
+                            tcx,
+                            poly_trait_ref,
+                            ty::BoundConstness::Maybe,
+                            span,
+                        );
                     }
                 }
                 hir::BoundConstness::Always(_) | hir::BoundConstness::Never => {}

compiler/rustc_hir_typeck/src/callee.rs

@@ -853,9 +853,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
         let host = match self.tcx.hir().body_const_context(self.body_id) {
             Some(hir::ConstContext::Const { .. } | hir::ConstContext::Static(_)) => {
-                ty::HostPolarity::Const
+                ty::BoundConstness::Const
             }
-            Some(hir::ConstContext::ConstFn) => ty::HostPolarity::Maybe,
+            Some(hir::ConstContext::ConstFn) => ty::BoundConstness::Maybe,
             None => return,
         };
 

compiler/rustc_middle/src/ty/context.rs

@@ -76,8 +76,8 @@ use crate::traits::solve::{
 };
 use crate::ty::predicate::ExistentialPredicateStableCmpExt as _;
 use crate::ty::{
-    self, AdtDef, AdtDefData, AdtKind, Binder, Clause, Clauses, Const, GenericArg, GenericArgs,
-    GenericArgsRef, GenericParamDefKind, HostPolarity, ImplPolarity, List, ListWithCachedTypeInfo,
+    self, AdtDef, AdtDefData, AdtKind, Binder, BoundConstness, Clause, Clauses, Const, GenericArg,
+    GenericArgs, GenericArgsRef, GenericParamDefKind, ImplPolarity, List, ListWithCachedTypeInfo,
     ParamConst, ParamTy, Pattern, PatternKind, PolyExistentialPredicate, PolyFnSig, Predicate,
     PredicateKind, PredicatePolarity, Region, RegionKind, ReprOptions, TraitObjectVisitor, Ty,
     TyKind, TyVid, Visibility,
@@ -2205,7 +2205,7 @@ macro_rules! nop_slice_lift {
 nop_slice_lift! {ty::ValTree<'a> => ty::ValTree<'tcx>}
 
 TrivialLiftImpls! {
-    ImplPolarity, PredicatePolarity, Promoted, HostPolarity,
+    ImplPolarity, PredicatePolarity, Promoted, BoundConstness,
 }
 
 macro_rules! sty_debug_print {

compiler/rustc_middle/src/ty/flags.rs

@@ -267,7 +267,7 @@ impl FlagComputation {
             }
             ty::PredicateKind::Clause(ty::ClauseKind::HostEffect(ty::HostEffectPredicate {
                 trait_ref,
-                host: _,
+                constness: _,
             })) => {
                 self.add_args(trait_ref.args);
             }

compiler/rustc_middle/src/ty/print/pretty.rs

@@ -1959,7 +1959,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
             ty::BoundConstness::Const => {
                 p!("const ");
             }
-            ty::BoundConstness::ConstIfConst => {
+            ty::BoundConstness::Maybe => {
                 p!("~const ");
             }
         }
@@ -3076,9 +3076,9 @@ define_print! {
     }
 
     ty::HostEffectPredicate<'tcx> {
-        let constness = match self.host {
-            ty::HostPolarity::Const => { "const" }
-            ty::HostPolarity::Maybe => { "~const" }
+        let constness = match self.constness {
+            ty::BoundConstness::Const => { "const" }
+            ty::BoundConstness::Maybe => { "~const" }
         };
         p!(print(self.trait_ref.self_ty()), ": {constness} ");
         p!(print(self.trait_ref.print_trait_sugared()))

compiler/rustc_next_trait_solver/src/solve/effect_goals.rs

@@ -44,7 +44,7 @@ where
     ) -> Result<Candidate<I>, NoSolution> {
         if let Some(host_clause) = assumption.as_host_effect_clause() {
             if host_clause.def_id() == goal.predicate.def_id()
-                && host_clause.host().satisfies(goal.predicate.host)
+                && host_clause.constness().satisfies(goal.predicate.constness)
             {
                 if !DeepRejectCtxt::relate_rigid_rigid(ecx.cx()).args_may_unify(
                     goal.predicate.trait_ref.args,
@@ -91,7 +91,7 @@ where
             cx,
             cx.implied_const_bounds(alias_ty.def_id)
                 .iter_instantiated(cx, alias_ty.args)
-                .map(|trait_ref| trait_ref.to_host_effect_clause(cx, goal.predicate.host)),
+                .map(|trait_ref| trait_ref.to_host_effect_clause(cx, goal.predicate.constness)),
         ) {
             candidates.extend(Self::probe_and_match_goal_against_assumption(
                 ecx,
@@ -107,7 +107,7 @@ where
                             .map(|trait_ref| {
                                 goal.with(
                                     cx,
-                                    trait_ref.to_host_effect_clause(cx, goal.predicate.host),
+                                    trait_ref.to_host_effect_clause(cx, goal.predicate.constness),
                                 )
                             }),
                     );
@@ -163,7 +163,10 @@ where
                 .const_conditions(impl_def_id)
                 .iter_instantiated(cx, impl_args)
                 .map(|bound_trait_ref| {
-                    goal.with(cx, bound_trait_ref.to_host_effect_clause(cx, goal.predicate.host))
+                    goal.with(
+                        cx,
+                        bound_trait_ref.to_host_effect_clause(cx, goal.predicate.constness),
+                    )
                 });
             ecx.add_goals(GoalSource::ImplWhereBound, const_conditions);
 

compiler/rustc_privacy/src/lib.rs

@@ -139,7 +139,7 @@ where
             }
             ty::ClauseKind::HostEffect(pred) => {
                 try_visit!(self.visit_trait(pred.trait_ref));
-                pred.host.visit_with(self)
+                pred.constness.visit_with(self)
             }
             ty::ClauseKind::Projection(ty::ProjectionPredicate {
                 projection_term: projection_ty,

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

@@ -545,10 +545,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                                 polarity: ty::PredicatePolarity::Positive,
                             }),
                             None,
-                            Some(match predicate.host {
-                                ty::HostPolarity::Maybe => ty::BoundConstness::ConstIfConst,
-                                ty::HostPolarity::Const => ty::BoundConstness::Const,
-                            }),
+                            Some(predicate.constness),
                             None,
                             String::new(),
                         );
@@ -2238,18 +2235,16 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                     (None, _) => Some(cannot_do_this),
                     // suggested using default post message
                     (
-                        Some(ty::BoundConstness::Const | ty::BoundConstness::ConstIfConst),
+                        Some(ty::BoundConstness::Const | ty::BoundConstness::Maybe),
                         Some(AppendConstMessage::Default),
                     ) => Some(format!("{cannot_do_this} in const contexts")),
                     // overridden post message
                     (
-                        Some(ty::BoundConstness::Const | ty::BoundConstness::ConstIfConst),
+                        Some(ty::BoundConstness::Const | ty::BoundConstness::Maybe),
                         Some(AppendConstMessage::Custom(custom_msg, _)),
                     ) => Some(format!("{cannot_do_this}{custom_msg}")),
                     // fallback to generic message
-                    (Some(ty::BoundConstness::Const | ty::BoundConstness::ConstIfConst), None) => {
-                        None
-                    }
+                    (Some(ty::BoundConstness::Const | ty::BoundConstness::Maybe), None) => None,
                 }
             })
             .unwrap_or_else(|| {

compiler/rustc_trait_selection/src/traits/effects.rs

@@ -47,7 +47,7 @@ fn match_candidate<'tcx>(
     obligation: &HostEffectObligation<'tcx>,
     candidate: ty::Binder<'tcx, ty::HostEffectPredicate<'tcx>>,
 ) -> Result<ThinVec<PredicateObligation<'tcx>>, NoSolution> {
-    if !candidate.skip_binder().host.satisfies(obligation.predicate.host) {
+    if !candidate.skip_binder().constness.satisfies(obligation.predicate.constness) {
         return Err(NoSolution);
     }
 
@@ -135,7 +135,8 @@ fn evaluate_host_effect_from_selection_candiate<'tcx>(
                             .map(|(trait_ref, _)| {
                                 obligation.with(
                                     tcx,
-                                    trait_ref.to_host_effect_clause(tcx, obligation.predicate.host),
+                                    trait_ref
+                                        .to_host_effect_clause(tcx, obligation.predicate.constness),
                                 )
                             }),
                     );

compiler/rustc_ty_utils/src/ty.rs

@@ -155,7 +155,7 @@ fn param_env(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ParamEnv<'_> {
     if tcx.is_conditionally_const(def_id) {
         predicates.extend(
             tcx.const_conditions(def_id).instantiate_identity(tcx).into_iter().map(
-                |(trait_ref, _)| trait_ref.to_host_effect_clause(tcx, ty::HostPolarity::Maybe),
+                |(trait_ref, _)| trait_ref.to_host_effect_clause(tcx, ty::BoundConstness::Maybe),
             ),
         );
     }

compiler/rustc_type_ir/src/elaborate.rs

@@ -160,7 +160,7 @@ impl<I: Interner, O: Elaboratable<I>> Elaborator<I, O> {
                 cx.implied_const_bounds(data.def_id()).iter_identity().map(|trait_ref| {
                     elaboratable.child(
                         trait_ref
-                            .to_host_effect_clause(cx, data.host)
+                            .to_host_effect_clause(cx, data.constness)
                             .instantiate_supertrait(cx, bound_clause.rebind(data.trait_ref)),
                     )
                 }),

compiler/rustc_type_ir/src/predicate.rs

@@ -112,9 +112,9 @@ impl<I: Interner> ty::Binder<I, TraitRef<I>> {
         self.skip_binder().def_id
     }
 
-    pub fn to_host_effect_clause(self, cx: I, host: HostPolarity) -> I::Clause {
+    pub fn to_host_effect_clause(self, cx: I, constness: BoundConstness) -> I::Clause {
         self.map_bound(|trait_ref| {
-            ty::ClauseKind::HostEffect(HostEffectPredicate { trait_ref, host })
+            ty::ClauseKind::HostEffect(HostEffectPredicate { trait_ref, constness })
         })
         .upcast(cx)
     }
@@ -757,7 +757,7 @@ impl<I: Interner> fmt::Debug for NormalizesTo<I> {
 #[cfg_attr(feature = "nightly", derive(TyEncodable, TyDecodable, HashStable_NoContext))]
 pub struct HostEffectPredicate<I: Interner> {
     pub trait_ref: ty::TraitRef<I>,
-    pub host: HostPolarity,
+    pub constness: BoundConstness,
 }
 
 impl<I: Interner> HostEffectPredicate<I> {
@@ -785,28 +785,8 @@ impl<I: Interner> ty::Binder<I, HostEffectPredicate<I>> {
     }
 
     #[inline]
-    pub fn host(self) -> HostPolarity {
-        self.skip_binder().host
-    }
-}
-
-#[derive(Clone, Copy, Hash, PartialEq, Eq, Debug)]
-#[derive(TypeVisitable_Generic, TypeFoldable_Generic)]
-#[cfg_attr(feature = "nightly", derive(TyEncodable, TyDecodable, HashStable_NoContext))]
-pub enum HostPolarity {
-    /// May be called in const environments if the callee is const.
-    Maybe,
-    /// Always allowed to be called in const environments.
-    Const,
-}
-
-impl HostPolarity {
-    pub fn satisfies(self, goal: HostPolarity) -> bool {
-        match (self, goal) {
-            (HostPolarity::Const, HostPolarity::Const | HostPolarity::Maybe) => true,
-            (HostPolarity::Maybe, HostPolarity::Maybe) => true,
-            (HostPolarity::Maybe, HostPolarity::Const) => false,
-        }
+    pub fn constness(self) -> BoundConstness {
+        self.skip_binder().constness
     }
 }
 
@@ -831,8 +811,8 @@ pub struct CoercePredicate<I: Interner> {
     pub b: I::Ty,
 }
 
-#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
-#[cfg_attr(feature = "nightly", derive(HashStable_NoContext, TyEncodable, TyDecodable))]
+#[derive(Clone, Copy, Hash, PartialEq, Eq, Debug)]
+#[cfg_attr(feature = "nightly", derive(TyEncodable, TyDecodable, HashStable_NoContext))]
 pub enum BoundConstness {
     /// `Type: const Trait`
     ///
@@ -841,14 +821,22 @@ pub enum BoundConstness {
     /// `Type: ~const Trait`
     ///
     /// Requires resolving to const only when we are in a const context.
-    ConstIfConst,
+    Maybe,
 }
 
 impl BoundConstness {
+    pub fn satisfies(self, goal: BoundConstness) -> bool {
+        match (self, goal) {
+            (BoundConstness::Const, BoundConstness::Const | BoundConstness::Maybe) => true,
+            (BoundConstness::Maybe, BoundConstness::Maybe) => true,
+            (BoundConstness::Maybe, BoundConstness::Const) => false,
+        }
+    }
+
     pub fn as_str(self) -> &'static str {
         match self {
             Self::Const => "const",
-            Self::ConstIfConst => "~const",
+            Self::Maybe => "~const",
         }
     }
 }
@@ -857,14 +845,7 @@ impl fmt::Display for BoundConstness {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
             Self::Const => f.write_str("const"),
-            Self::ConstIfConst => f.write_str("~const"),
+            Self::Maybe => f.write_str("~const"),
         }
     }
 }
-
-impl<I> Lift<I> for BoundConstness {
-    type Lifted = BoundConstness;
-    fn lift_to_interner(self, _: I) -> Option<Self::Lifted> {
-        Some(self)
-    }
-}