Add with_opt_const_effect_param helper, simplify

compiler/rustc_hir_typeck/src/callee.rs

@@ -8,7 +8,6 @@ use rustc_errors::{Applicability, Diagnostic, ErrorGuaranteed, StashKey};
 use rustc_hir as hir;
 use rustc_hir::def::{self, CtorKind, Namespace, Res};
 use rustc_hir::def_id::DefId;
-use rustc_hir::HirId;
 use rustc_hir_analysis::autoderef::Autoderef;
 use rustc_infer::{
     infer,
@@ -373,7 +372,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     ) -> Ty<'tcx> {
         let (fn_sig, def_id) = match *callee_ty.kind() {
             ty::FnDef(def_id, args) => {
-                self.enforce_context_effects(call_expr.hir_id, call_expr.span, def_id, args);
+                self.enforce_context_effects(call_expr.span, def_id, args);
                 let fn_sig = self.tcx.fn_sig(def_id).instantiate(self.tcx, args);
 
                 // Unit testing: function items annotated with
@@ -770,7 +769,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     #[tracing::instrument(level = "debug", skip(self, span))]
     pub(super) fn enforce_context_effects(
         &self,
-        call_expr_hir: HirId,
         span: Span,
         callee_did: DefId,
         callee_args: GenericArgsRef<'tcx>,

compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs

@@ -165,7 +165,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         span: Span,
         method: MethodCallee<'tcx>,
     ) {
-        self.enforce_context_effects(hir_id, span, method.def_id, method.args);
+        self.enforce_context_effects(span, method.def_id, method.args);
         self.write_resolution(hir_id, Ok((DefKind::AssocFn, method.def_id)));
         self.write_args(hir_id, method.args);
     }

compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs

@@ -282,12 +282,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                                 span: provided_arg.span,
                             });
                         } else {
-                            self.enforce_context_effects(
-                                provided_arg.hir_id,
-                                provided_arg.span,
-                                def_id,
-                                args,
-                            )
+                            self.enforce_context_effects(provided_arg.span, def_id, args)
                         }
                     }
                 } else {

compiler/rustc_middle/src/ty/util.rs

@@ -813,6 +813,23 @@ impl<'tcx> TyCtxt<'tcx> {
             None => self.consts.true_,
         }
     }
+
+    /// Constructs generic args for an item, optionally appending a const effect param type
+    pub fn with_opt_const_effect_param(
+        self,
+        caller_def_id: LocalDefId,
+        callee_def_id: DefId,
+        args: impl IntoIterator<Item: Into<ty::GenericArg<'tcx>>>,
+    ) -> ty::GenericArgsRef<'tcx> {
+        let generics = self.generics_of(callee_def_id);
+        assert_eq!(generics.parent, None);
+
+        let opt_const_param = generics.host_effect_index.is_some().then(|| {
+            ty::GenericArg::from(self.expected_const_effect_param_for_body(caller_def_id))
+        });
+
+        self.mk_args_from_iter(args.into_iter().map(|arg| arg.into()).chain(opt_const_param))
+    }
 }
 
 struct OpaqueTypeExpander<'tcx> {

compiler/rustc_mir_build/src/build/matches/test.rs

@@ -494,14 +494,12 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         }
 
         let eq_def_id = self.tcx.require_lang_item(LangItem::PartialEq, Some(source_info.span));
-
-        let mut args: Vec<ty::GenericArg<'tcx>> = vec![ty.into(), ty.into()];
-        // If `PartialEq` is `#[const_trait]`, then add a const effect param
-        if self.tcx.generics_of(eq_def_id).host_effect_index.is_some() {
-            args.push(self.tcx.expected_const_effect_param_for_body(self.def_id).into());
-        }
-
-        let method = trait_method(self.tcx, eq_def_id, sym::eq, args);
+        let method = trait_method(
+            self.tcx,
+            eq_def_id,
+            sym::eq,
+            self.tcx.with_opt_const_effect_param(self.def_id, eq_def_id, [ty, ty]),
+        );
 
         let bool_ty = self.tcx.types.bool;
         let eq_result = self.temp(bool_ty, source_info.span);

compiler/rustc_mir_build/src/thir/pattern/const_to_pat.rs

@@ -265,20 +265,19 @@ impl<'tcx> ConstToPat<'tcx> {
         // error, because that's never worked, due to compiler
         // using `PartialEq::eq` in this scenario in the past.)
         let partial_eq_trait_id = tcx.require_lang_item(hir::LangItem::PartialEq, Some(self.span));
-        let mut args: Vec<ty::GenericArg<'tcx>> = vec![ty.into(), ty.into()];
-        // If `PartialEq` is `#[const_trait]`, then add a const effect param
-        if tcx.generics_of(partial_eq_trait_id).host_effect_index.is_some() {
-            args.push(
-                tcx.expected_const_effect_param_for_body(tcx.hir().enclosing_body_owner(self.id))
-                    .into(),
-            );
-        }
-
         let partial_eq_obligation = Obligation::new(
             tcx,
             ObligationCause::dummy(),
             self.param_env,
-            ty::TraitRef::new(tcx, partial_eq_trait_id, args),
+            ty::TraitRef::new(
+                tcx,
+                partial_eq_trait_id,
+                tcx.with_opt_const_effect_param(
+                    tcx.hir().enclosing_body_owner(self.id),
+                    partial_eq_trait_id,
+                    [ty, ty],
+                ),
+            ),
         );
 
         // This *could* accept a type that isn't actually `PartialEq`, because region bounds get

tests/ui/rfcs/rfc-2632-const-trait-impl/effects/minicore.rs

@@ -344,9 +344,9 @@ trait PartialEq<Rhs: ?Sized = Self> {
     }
 }
 
-impl<A: ?Sized, B: ?Sized> PartialEq<&B> for &A
+impl<A: ?Sized, B: ?Sized> const PartialEq<&B> for &A
 where
-    A: PartialEq<B>,
+    A: ~const PartialEq<B>,
 {
     fn eq(&self, other: &&B) -> bool {
         PartialEq::eq(*self, *other)