Rollup merge of #131931 - compiler-errors:constness-valid, r=fmease

Remove unnecessary constness from `lower_generic_args_of_path`

We pass `NotConst` to all callsites of `lower_generic_args_of_path` except for `lower_poly_trait_ref`, so let's not do that.

compiler/rustc_hir_analysis/src/hir_ty_lowering/bounds.rs

@@ -516,7 +516,6 @@ pub fn lower_ty_maybe_return_type_notation(&self, hir_ty: &hir::Ty<'tcx>) -> Ty<
                     self_ty,
                     trait_segment,
                     false,
-                    ty::BoundConstness::NotConst,
                 );
 
                 // SUBTLE: As noted at the end of `try_append_return_type_notation_params`

compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs

@@ -336,14 +336,7 @@ pub fn lower_generic_args_of_path_segment(
         def_id: DefId,
         item_segment: &hir::PathSegment<'tcx>,
     ) -> GenericArgsRef<'tcx> {
-        let (args, _) = self.lower_generic_args_of_path(
+        let (args, _) = self.lower_generic_args_of_path(span, def_id, &[], item_segment, None);
-            span,
-            def_id,
-            &[],
-            item_segment,
-            None,
-            ty::BoundConstness::NotConst,
-        );
         if let Some(c) = item_segment.args().constraints.first() {
             prohibit_assoc_item_constraint(self, c, Some((def_id, item_segment, span)));
         }
@@ -392,7 +385,6 @@ fn lower_generic_args_of_path(
         parent_args: &[ty::GenericArg<'tcx>],
         segment: &hir::PathSegment<'tcx>,
         self_ty: Option<Ty<'tcx>>,
-        constness: ty::BoundConstness,
     ) -> (GenericArgsRef<'tcx>, GenericArgCountResult) {
         // If the type is parameterized by this region, then replace this
         // region with the current anon region binding (in other words,
@@ -415,7 +407,7 @@ fn lower_generic_args_of_path(
             assert!(self_ty.is_none());
         }
 
-        let mut arg_count = check_generic_arg_count(
+        let arg_count = check_generic_arg_count(
             self,
             def_id,
             segment,
@@ -573,16 +565,6 @@ fn inferred_kind(
                 }
             }
         }
-        if let ty::BoundConstness::Const | ty::BoundConstness::ConstIfConst = constness
-            && generics.has_self
-            && !tcx.is_const_trait(def_id)
-        {
-            let reported = self.dcx().emit_err(crate::errors::ConstBoundForNonConstTrait {
-                span,
-                modifier: constness.as_str(),
-            });
-            arg_count.correct = Err(GenericArgCountMismatch { reported, invalid_args: vec![] });
-        }
 
         let mut args_ctx = GenericArgsCtxt {
             lowerer: self,
@@ -614,14 +596,8 @@ pub fn lower_generic_args_of_assoc_item(
         parent_args: GenericArgsRef<'tcx>,
     ) -> GenericArgsRef<'tcx> {
         debug!(?span, ?item_def_id, ?item_segment);
-        let (args, _) = self.lower_generic_args_of_path(
+        let (args, _) =
-            span,
+            self.lower_generic_args_of_path(span, item_def_id, parent_args, item_segment, None);
-            item_def_id,
-            parent_args,
-            item_segment,
-            None,
-            ty::BoundConstness::NotConst,
-        );
         if let Some(c) = item_segment.args().constraints.first() {
             prohibit_assoc_item_constraint(self, c, Some((item_def_id, item_segment, span)));
         }
@@ -647,7 +623,6 @@ pub fn lower_impl_trait_ref(
             self_ty,
             trait_ref.path.segments.last().unwrap(),
             true,
-            ty::BoundConstness::NotConst,
         )
     }
 
@@ -700,9 +675,17 @@ pub(crate) fn lower_poly_trait_ref(
             &[],
             trait_segment,
             Some(self_ty),
-            constness,
         );
 
+        if let ty::BoundConstness::Const | ty::BoundConstness::ConstIfConst = constness
+            && !self.tcx().is_const_trait(trait_def_id)
+        {
+            self.dcx().emit_err(crate::errors::ConstBoundForNonConstTrait {
+                span: trait_ref.path.span,
+                modifier: constness.as_str(),
+            });
+        }
+
         let tcx = self.tcx();
         let bound_vars = tcx.late_bound_vars(trait_ref.hir_ref_id);
         debug!(?bound_vars);
@@ -762,19 +745,11 @@ fn lower_mono_trait_ref(
         self_ty: Ty<'tcx>,
         trait_segment: &hir::PathSegment<'tcx>,
         is_impl: bool,
-        // FIXME(effects): Move all host param things in HIR ty lowering to AST lowering.
-        constness: ty::BoundConstness,
     ) -> ty::TraitRef<'tcx> {
         self.complain_about_internal_fn_trait(span, trait_def_id, trait_segment, is_impl);
 
-        let (generic_args, _) = self.lower_generic_args_of_path(
+        let (generic_args, _) =
-            span,
+            self.lower_generic_args_of_path(span, trait_def_id, &[], trait_segment, Some(self_ty));
-            trait_def_id,
-            &[],
-            trait_segment,
-            Some(self_ty),
-            constness,
-        );
         if let Some(c) = trait_segment.args().constraints.first() {
             prohibit_assoc_item_constraint(self, c, Some((trait_def_id, trait_segment, span)));
         }
@@ -1542,7 +1517,6 @@ fn lower_qpath(
         item_def_id: DefId,
         trait_segment: &hir::PathSegment<'tcx>,
         item_segment: &hir::PathSegment<'tcx>,
-        constness: ty::BoundConstness,
     ) -> Ty<'tcx> {
         let tcx = self.tcx();
 
@@ -1555,7 +1529,7 @@ fn lower_qpath(
         debug!(?self_ty);
 
         let trait_ref =
-            self.lower_mono_trait_ref(span, trait_def_id, self_ty, trait_segment, false, constness);
+            self.lower_mono_trait_ref(span, trait_def_id, self_ty, trait_segment, false);
         debug!(?trait_ref);
 
         let item_args =
@@ -1918,7 +1892,6 @@ pub fn lower_path(
                     def_id,
                     &path.segments[path.segments.len() - 2],
                     path.segments.last().unwrap(),
-                    ty::BoundConstness::NotConst,
                 )
             }
             Res::PrimTy(prim_ty) => {
@@ -2151,7 +2124,6 @@ pub fn lower_ty(&self, hir_ty: &hir::Ty<'tcx>) -> Ty<'tcx> {
                     &[],
                     &hir::PathSegment::invalid(),
                     None,
-                    ty::BoundConstness::NotConst,
                 );
                 tcx.at(span).type_of(def_id).instantiate(tcx, args)
             }