Auto merge of rust-lang#114781 - fee1-dead-contrib:param-impl-source, r=davidtwco

Remove constness from `ImplSource::Param`

Author: bors

compiler/rustc_ast_lowering/src/lib.rs

@@ -2495,35 +2495,31 @@ impl<'hir> GenericArgsCtor<'hir> {
 
         let id = lcx.next_node_id();
         let hir_id = lcx.next_id();
+
+        let Some(host_param_id) = lcx.host_param_id else {
+            lcx.tcx
+                .sess
+                .delay_span_bug(span, "no host param id for call in const yet no errors reported");
+            return;
+        };
+
         let body = lcx.lower_body(|lcx| {
-            (
-                &[],
-                match constness {
-                    ast::Const::Yes(_) => {
-                        let hir_id = lcx.next_id();
-                        let res =
-                            Res::Def(DefKind::ConstParam, lcx.host_param_id.unwrap().to_def_id());
-                        let expr_kind = hir::ExprKind::Path(hir::QPath::Resolved(
-                            None,
-                            lcx.arena.alloc(hir::Path {
-                                span,
-                                res,
-                                segments: arena_vec![lcx; hir::PathSegment::new(Ident {
-                                    name: sym::host,
-                                    span,
-                                }, hir_id, res)],
-                            }),
-                        ));
-                        lcx.expr(span, expr_kind)
-                    }
-                    ast::Const::No => lcx.expr(
+            (&[], {
+                let hir_id = lcx.next_id();
+                let res = Res::Def(DefKind::ConstParam, host_param_id.to_def_id());
+                let expr_kind = hir::ExprKind::Path(hir::QPath::Resolved(
+                    None,
+                    lcx.arena.alloc(hir::Path {
                         span,
-                        hir::ExprKind::Lit(
-                            lcx.arena.alloc(hir::Lit { span, node: ast::LitKind::Bool(true) }),
-                        ),
-                    ),
-                },
-            )
+                        res,
+                        segments: arena_vec![lcx; hir::PathSegment::new(Ident {
+                            name: sym::host,
+                            span,
+                        }, hir_id, res)],
+                    }),
+                ));
+                lcx.expr(span, expr_kind)
+            })
         });
 
         let attr_id = lcx.tcx.sess.parse_sess.attr_id_generator.mk_attr_id();

compiler/rustc_const_eval/src/transform/check_consts/check.rs

@@ -772,7 +772,7 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
                     };
 
                     match implsrc {
-                        Ok(Some(ImplSource::Param(ty::BoundConstness::ConstIfConst, _))) => {
+                        Ok(Some(ImplSource::Param(_))) if tcx.features().effects => {
                             debug!(
                                 "const_trait_impl: provided {:?} via where-clause in {:?}",
                                 trait_ref, param_env

compiler/rustc_const_eval/src/transform/check_consts/qualifs.rs

@@ -174,8 +174,7 @@ impl Qualif for NeedsNonConstDrop {
 
         if !matches!(
             impl_src,
-            ImplSource::Builtin(BuiltinImplSource::Misc, _)
-                | ImplSource::Param(ty::BoundConstness::ConstIfConst, _)
+            ImplSource::Builtin(BuiltinImplSource::Misc, _) | ImplSource::Param(_)
         ) {
             // If our const destruct candidate is not ConstDestruct or implied by the param env,
             // then it's bad

compiler/rustc_middle/src/traits/mod.rs

@@ -649,7 +649,7 @@ pub enum ImplSource<'tcx, N> {
     /// for some type parameter. The `Vec<N>` represents the
     /// obligations incurred from normalizing the where-clause (if
     /// any).
-    Param(ty::BoundConstness, Vec<N>),
+    Param(Vec<N>),
 
     /// Successful resolution for a builtin impl.
     Builtin(BuiltinImplSource, Vec<N>),
@@ -659,21 +659,21 @@ impl<'tcx, N> ImplSource<'tcx, N> {
     pub fn nested_obligations(self) -> Vec<N> {
         match self {
             ImplSource::UserDefined(i) => i.nested,
-            ImplSource::Param(_, n) | ImplSource::Builtin(_, n) => n,
+            ImplSource::Param(n) | ImplSource::Builtin(_, n) => n,
         }
     }
 
     pub fn borrow_nested_obligations(&self) -> &[N] {
         match self {
             ImplSource::UserDefined(i) => &i.nested,
-            ImplSource::Param(_, n) | ImplSource::Builtin(_, n) => &n,
+            ImplSource::Param(n) | ImplSource::Builtin(_, n) => &n,
         }
     }
 
     pub fn borrow_nested_obligations_mut(&mut self) -> &mut [N] {
         match self {
             ImplSource::UserDefined(i) => &mut i.nested,
-            ImplSource::Param(_, n) | ImplSource::Builtin(_, n) => n,
+            ImplSource::Param(n) | ImplSource::Builtin(_, n) => n,
         }
     }
 
@@ -687,7 +687,7 @@ impl<'tcx, N> ImplSource<'tcx, N> {
                 args: i.args,
                 nested: i.nested.into_iter().map(f).collect(),
             }),
-            ImplSource::Param(ct, n) => ImplSource::Param(ct, n.into_iter().map(f).collect()),
+            ImplSource::Param(n) => ImplSource::Param(n.into_iter().map(f).collect()),
             ImplSource::Builtin(source, n) => {
                 ImplSource::Builtin(source, n.into_iter().map(f).collect())
             }

compiler/rustc_middle/src/traits/select.rs

@@ -127,6 +127,7 @@ pub enum SelectionCandidate<'tcx> {
     /// an applicable bound in the trait definition. The `usize` is an index
     /// into the list returned by `tcx.item_bounds`. The constness is the
     /// constness of the bound in the trait.
+    // FIXME(effects) do we need this constness
     ProjectionCandidate(usize, ty::BoundConstness),
 
     /// Implementation of a `Fn`-family trait by one of the anonymous types

compiler/rustc_middle/src/traits/structural_impls.rs

@@ -13,8 +13,8 @@ impl<'tcx, N: fmt::Debug> fmt::Debug for traits::ImplSource<'tcx, N> {
                 write!(f, "Builtin({source:?}, {d:?})")
             }
 
-            super::ImplSource::Param(ct, n) => {
-                write!(f, "ImplSourceParamData({n:?}, {ct:?})")
+            super::ImplSource::Param(n) => {
+                write!(f, "ImplSourceParamData({n:?})")
             }
         }
     }

compiler/rustc_trait_selection/src/solve/eval_ctxt/select.rs

@@ -123,7 +123,7 @@ impl<'tcx> InferCtxtSelectExt<'tcx> for InferCtxt<'tcx> {
             // It's fine not to do anything to rematch these, since there are no
             // nested obligations.
             (Certainty::Yes, CandidateSource::ParamEnv(_) | CandidateSource::AliasBound) => {
-                Ok(Some(ImplSource::Param(ty::BoundConstness::NotConst, nested_obligations)))
+                Ok(Some(ImplSource::Param(nested_obligations)))
             }
 
             (Certainty::Maybe(_), _) => Ok(None),

compiler/rustc_trait_selection/src/traits/select/confirmation.rs

@@ -59,8 +59,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
             ParamCandidate(param) => {
                 let obligations =
                     self.confirm_param_candidate(obligation, param.map_bound(|t| t.trait_ref));
-                // FIXME(effects)
-                ImplSource::Param(ty::BoundConstness::NotConst, obligations)
+                ImplSource::Param(obligations)
             }
 
             ImplCandidate(impl_def_id) => {
@@ -72,9 +71,9 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                 ImplSource::Builtin(BuiltinImplSource::Misc, data)
             }
 
-            ProjectionCandidate(idx, constness) => {
+            ProjectionCandidate(idx, _) => {
                 let obligations = self.confirm_projection_candidate(obligation, idx)?;
-                ImplSource::Param(constness, obligations)
+                ImplSource::Param(obligations)
             }
 
             ObjectCandidate(idx) => self.confirm_object_candidate(obligation, idx)?,

src/tools/clippy/clippy_utils/src/qualify_min_const_fn.rs

@@ -415,7 +415,7 @@ fn is_ty_const_destruct<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>, body: &Body<'tcx>
 
         if !matches!(
             impl_src,
-            ImplSource::Builtin(BuiltinImplSource::Misc, _) | ImplSource::Param(ty::BoundConstness::ConstIfConst, _)
+            ImplSource::Builtin(BuiltinImplSource::Misc, _) | ImplSource::Param(_)
         ) {
             return false;
         }

tests/ui/rfcs/rfc-2632-const-trait-impl/assoc-type-const-bound-usage.rs

@@ -1,6 +1,6 @@
 // known-bug: #110395
 // FIXME check-pass
-#![feature(const_trait_impl)]
+#![feature(const_trait_impl, effects)]
 
 #[const_trait]
 trait Foo {