Auto merge of #91354 - fee1-dead:const_env, r=spastorino

Cleanup: Eliminate ConstnessAnd

This is almost a behaviour-free change and purely a refactoring. "almost" because we appear to be using the wrong ParamEnv somewhere already, and this is now exposed by failing a test using the unstable `~const` feature.

We most definitely need to review all `without_const` and at some point should probably get rid of many of them by using `TraitPredicate` instead of `TraitRef`.

This is a continuation of https://github.com/rust-lang/rust/pull/90274.

r? `@oli-obk`

cc `@spastorino` `@ecstatic-morse`

compiler/rustc_typeck/src/astconv/mod.rs

@@ -1588,7 +1588,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                 traits::transitive_bounds_that_define_assoc_type(
                     tcx,
                     predicates.iter().filter_map(|(p, _)| {
-                        p.to_opt_poly_trait_ref().map(|trait_ref| trait_ref.value)
+                        Some(p.to_opt_poly_trait_pred()?.map_bound(|t| t.trait_ref))
                     }),
                     assoc_name,
                 )

compiler/rustc_typeck/src/bounds.rs

@@ -1,7 +1,7 @@
 //! Bounds are restrictions applied to some types after they've been converted into the
 //! `ty` form from the HIR.
 
-use rustc_middle::ty::{self, ToPredicate, Ty, TyCtxt, WithConstness};
+use rustc_middle::ty::{self, ToPredicate, Ty, TyCtxt};
 use rustc_span::Span;
 
 /// Collects together a list of type bounds. These lists of bounds occur in many places

compiler/rustc_typeck/src/check/compare_method.rs

@@ -208,8 +208,11 @@ fn compare_predicate_entailment<'tcx>(
     // The key step here is to update the caller_bounds's predicates to be
     // the new hybrid bounds we computed.
     let normalize_cause = traits::ObligationCause::misc(impl_m_span, impl_m_hir_id);
-    let param_env =
-        ty::ParamEnv::new(tcx.intern_predicates(&hybrid_preds.predicates), Reveal::UserFacing);
+    let param_env = ty::ParamEnv::new(
+        tcx.intern_predicates(&hybrid_preds.predicates),
+        Reveal::UserFacing,
+        hir::Constness::NotConst,
+    );
     let param_env =
         traits::normalize_param_env_or_error(tcx, impl_m.def_id, param_env, normalize_cause);
 
@@ -1165,8 +1168,11 @@ fn compare_type_predicate_entailment<'tcx>(
     debug!("compare_type_predicate_entailment: bounds={:?}", hybrid_preds);
 
     let normalize_cause = traits::ObligationCause::misc(impl_ty_span, impl_ty_hir_id);
-    let param_env =
-        ty::ParamEnv::new(tcx.intern_predicates(&hybrid_preds.predicates), Reveal::UserFacing);
+    let param_env = ty::ParamEnv::new(
+        tcx.intern_predicates(&hybrid_preds.predicates),
+        Reveal::UserFacing,
+        hir::Constness::NotConst,
+    );
     let param_env = traits::normalize_param_env_or_error(
         tcx,
         impl_ty.def_id,
@@ -1351,7 +1357,11 @@ pub fn check_type_bounds<'tcx>(
                 .to_predicate(tcx),
             ),
         };
-        ty::ParamEnv::new(tcx.intern_predicates(&predicates), Reveal::UserFacing)
+        ty::ParamEnv::new(
+            tcx.intern_predicates(&predicates),
+            Reveal::UserFacing,
+            param_env.constness(),
+        )
     };
     debug!(?normalize_param_env);
 
@@ -1360,13 +1370,7 @@ pub fn check_type_bounds<'tcx>(
         impl_ty_substs.rebase_onto(tcx, impl_ty.container.id(), impl_trait_ref.substs);
 
     tcx.infer_ctxt().enter(move |infcx| {
-        let constness = impl_ty
-            .container
-            .impl_def_id()
-            .map(|did| tcx.impl_constness(did))
-            .unwrap_or(hir::Constness::NotConst);
-
-        let inh = Inherited::with_constness(infcx, impl_ty.def_id.expect_local(), constness);
+        let inh = Inherited::new(infcx, impl_ty.def_id.expect_local());
         let infcx = &inh.infcx;
         let mut selcx = traits::SelectionContext::new(&infcx);
 
@@ -1410,8 +1414,7 @@ pub fn check_type_bounds<'tcx>(
 
         // Check that all obligations are satisfied by the implementation's
         // version.
-        let errors =
-            inh.fulfillment_cx.borrow_mut().select_all_with_constness_or_error(&infcx, constness);
+        let errors = inh.fulfillment_cx.borrow_mut().select_all_or_error(&infcx);
         if !errors.is_empty() {
             infcx.report_fulfillment_errors(&errors, None, false);
             return Err(ErrorReported);

compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs

@@ -610,10 +610,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
     #[instrument(skip(self), level = "debug")]
     pub(in super::super) fn select_all_obligations_or_error(&self) {
-        let errors = self
-            .fulfillment_cx
-            .borrow_mut()
-            .select_all_with_constness_or_error(&self, self.inh.constness);
+        let errors = self.fulfillment_cx.borrow_mut().select_all_or_error(&self);
 
         if !errors.is_empty() {
             self.report_fulfillment_errors(&errors, self.inh.body_id, false);
@@ -626,10 +623,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         fallback_has_occurred: bool,
         mutate_fulfillment_errors: impl Fn(&mut Vec<traits::FulfillmentError<'tcx>>),
     ) {
-        let mut result = self
-            .fulfillment_cx
-            .borrow_mut()
-            .select_with_constness_where_possible(self, self.inh.constness);
+        let mut result = self.fulfillment_cx.borrow_mut().select_where_possible(self);
         if !result.is_empty() {
             mutate_fulfillment_errors(&mut result);
             self.report_fulfillment_errors(&result, self.inh.body_id, fallback_has_occurred);

compiler/rustc_typeck/src/check/inherited.rs

@@ -53,9 +53,6 @@ pub struct Inherited<'a, 'tcx> {
     pub(super) deferred_generator_interiors:
         RefCell<Vec<(hir::BodyId, Ty<'tcx>, hir::GeneratorKind)>>,
 
-    /// Reports whether this is in a const context.
-    pub(super) constness: hir::Constness,
-
     pub(super) body_id: Option<hir::BodyId>,
 
     /// Whenever we introduce an adjustment from `!` into a type variable,
@@ -102,16 +99,6 @@ impl<'tcx> InheritedBuilder<'tcx> {
 
 impl Inherited<'a, 'tcx> {
     pub(super) fn new(infcx: InferCtxt<'a, 'tcx>, def_id: LocalDefId) -> Self {
-        let tcx = infcx.tcx;
-        let item_id = tcx.hir().local_def_id_to_hir_id(def_id);
-        Self::with_constness(infcx, def_id, tcx.hir().get(item_id).constness_for_typeck())
-    }
-
-    pub(super) fn with_constness(
-        infcx: InferCtxt<'a, 'tcx>,
-        def_id: LocalDefId,
-        constness: hir::Constness,
-    ) -> Self {
         let tcx = infcx.tcx;
         let item_id = tcx.hir().local_def_id_to_hir_id(def_id);
         let body_id = tcx.hir().maybe_body_owned_by(item_id);
@@ -128,7 +115,6 @@ impl Inherited<'a, 'tcx> {
             deferred_cast_checks: RefCell::new(Vec::new()),
             deferred_generator_interiors: RefCell::new(Vec::new()),
             diverging_type_vars: RefCell::new(Default::default()),
-            constness,
             body_id,
         }
     }

compiler/rustc_typeck/src/check/method/mod.rs

@@ -22,7 +22,7 @@ use rustc_infer::infer::{self, InferOk};
 use rustc_middle::ty::subst::Subst;
 use rustc_middle::ty::subst::{InternalSubsts, SubstsRef};
 use rustc_middle::ty::GenericParamDefKind;
-use rustc_middle::ty::{self, ToPredicate, Ty, TypeFoldable, WithConstness};
+use rustc_middle::ty::{self, ToPredicate, Ty, TypeFoldable};
 use rustc_span::symbol::Ident;
 use rustc_span::Span;
 use rustc_trait_selection::traits;

compiler/rustc_typeck/src/check/method/probe.rs

@@ -21,7 +21,7 @@ use rustc_infer::infer::{self, InferOk, TyCtxtInferExt};
 use rustc_middle::middle::stability;
 use rustc_middle::ty::subst::{InternalSubsts, Subst, SubstsRef};
 use rustc_middle::ty::GenericParamDefKind;
-use rustc_middle::ty::{self, ParamEnvAnd, ToPredicate, Ty, TyCtxt, TypeFoldable, WithConstness};
+use rustc_middle::ty::{self, ParamEnvAnd, ToPredicate, Ty, TyCtxt, TypeFoldable};
 use rustc_session::lint;
 use rustc_span::def_id::LocalDefId;
 use rustc_span::lev_distance::{find_best_match_for_name, lev_distance};

compiler/rustc_typeck/src/check/method/suggest.rs

@@ -12,7 +12,7 @@ use rustc_hir::{ExprKind, Node, QPath};
 use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
 use rustc_middle::ty::fast_reject::simplify_type;
 use rustc_middle::ty::print::with_crate_prefix;
-use rustc_middle::ty::{self, ToPredicate, Ty, TyCtxt, TypeFoldable, WithConstness};
+use rustc_middle::ty::{self, ToPredicate, Ty, TyCtxt, TypeFoldable};
 use rustc_span::lev_distance;
 use rustc_span::symbol::{kw, sym, Ident};
 use rustc_span::{source_map, FileName, MultiSpan, Span, Symbol};

compiler/rustc_typeck/src/check/wfcheck.rs

@@ -21,7 +21,6 @@ use rustc_middle::ty::subst::{GenericArgKind, InternalSubsts, Subst};
 use rustc_middle::ty::trait_def::TraitSpecializationKind;
 use rustc_middle::ty::{
     self, AdtKind, GenericParamDefKind, ToPredicate, Ty, TyCtxt, TypeFoldable, TypeVisitor,
-    WithConstness,
 };
 use rustc_session::parse::feature_err;
 use rustc_span::symbol::{sym, Ident, Symbol};

compiler/rustc_typeck/src/collect.rs

@@ -41,7 +41,7 @@ use rustc_middle::ty::subst::InternalSubsts;
 use rustc_middle::ty::util::Discr;
 use rustc_middle::ty::util::IntTypeExt;
 use rustc_middle::ty::{self, AdtKind, Const, DefIdTree, Ty, TyCtxt};
-use rustc_middle::ty::{ReprOptions, ToPredicate, WithConstness};
+use rustc_middle::ty::{ReprOptions, ToPredicate};
 use rustc_session::lint;
 use rustc_session::parse::feature_err;
 use rustc_span::symbol::{kw, sym, Ident, Symbol};