Eliminate unnecessary parameter

compiler/rustc_hir_analysis/messages.ftl

@@ -37,7 +37,7 @@ hir_analysis_assoc_kind_mismatch = expected {$expected}, found {$got}
 
 hir_analysis_assoc_kind_mismatch_wrap_in_braces_sugg = consider adding braces here
 
-hir_analysis_associated_type_trait_uninferred_generic_params = cannot use the associated {$what} of a trait with uninferred generic parameters
+hir_analysis_associated_type_trait_uninferred_generic_params = cannot use the {$what} of a trait with uninferred generic parameters
     .suggestion = use a fully qualified path with inferred lifetimes
 
 hir_analysis_associated_type_trait_uninferred_generic_params_multipart_suggestion = use a fully qualified path with explicit lifetimes

compiler/rustc_hir_analysis/src/collect.rs

@@ -44,7 +44,6 @@ use rustc_trait_selection::traits::ObligationCtxt;
 use tracing::{debug, instrument};
 
 use crate::errors;
-use crate::hir_ty_lowering::errors::assoc_tag_str;
 use crate::hir_ty_lowering::{FeedConstTy, HirTyLowerer, RegionInferReason};
 
 pub(crate) mod dump;
@@ -450,7 +449,6 @@ impl<'tcx> HirTyLowerer<'tcx> for ItemCtxt<'tcx> {
         item_def_id: DefId,
         item_segment: &rustc_hir::PathSegment<'tcx>,
         poly_trait_ref: ty::PolyTraitRef<'tcx>,
-        assoc_tag: ty::AssocTag,
     ) -> Result<(DefId, ty::GenericArgsRef<'tcx>), ErrorGuaranteed> {
         if let Some(trait_ref) = poly_trait_ref.no_bound_vars() {
             let item_args = self.lowerer().lower_generic_args_of_assoc_item(
@@ -525,7 +523,7 @@ impl<'tcx> HirTyLowerer<'tcx> for ItemCtxt<'tcx> {
                 inferred_sugg,
                 bound,
                 mpart_sugg,
-                what: assoc_tag_str(assoc_tag),
+                what: self.tcx.def_descr(item_def_id),
             }))
         }
     }

compiler/rustc_hir_analysis/src/hir_ty_lowering/bounds.rs

@@ -803,6 +803,11 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
             }
         };
 
+        let trait_def_id = bound.def_id();
+        let assoc_fn = self
+            .probe_assoc_item(assoc_ident, ty::AssocTag::Fn, qpath_hir_id, span, trait_def_id)
+            .expect("failed to find associated fn");
+
         // Don't let `T::method` resolve to some `for<'a> <T as Tr<'a>>::method`,
         // which may happen via a higher-ranked where clause or supertrait.
         // This is the same restrictions as associated types; even though we could
@@ -815,16 +820,11 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                 inferred_sugg: Some(span.with_hi(item_segment.ident.span.lo())),
                 bound: format!("{}::", tcx.anonymize_bound_vars(bound).skip_binder(),),
                 mpart_sugg: None,
-                what: "function",
+                what: assoc_fn.descr(),
             }));
         }
 
-        let trait_def_id = bound.def_id();
-        let assoc_ty = self
-            .probe_assoc_item(assoc_ident, ty::AssocTag::Fn, qpath_hir_id, span, trait_def_id)
-            .expect("failed to find associated type");
-
-        Ok((bound, assoc_ty.def_id))
+        Ok((bound, assoc_fn.def_id))
     }
 
     /// Do the common parts of lowering an RTN type. This involves extending the

compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs

@@ -168,7 +168,6 @@ pub trait HirTyLowerer<'tcx> {
         item_def_id: DefId,
         item_segment: &hir::PathSegment<'tcx>,
         poly_trait_ref: ty::PolyTraitRef<'tcx>,
-        assoc_tag: ty::AssocTag,
     ) -> Result<(DefId, GenericArgsRef<'tcx>), ErrorGuaranteed>;
 
     fn lower_fn_sig(
@@ -1433,13 +1432,8 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         let assoc_item = self
             .probe_assoc_item(assoc_ident, mode.assoc_tag(), hir_ref_id, span, trait_did)
             .expect("failed to find associated item");
-        let (def_id, args) = self.lower_assoc_shared(
-            span,
-            assoc_item.def_id,
-            assoc_segment,
-            bound,
-            mode.assoc_tag(),
-        )?;
+        let (def_id, args) =
+            self.lower_assoc_shared(span, assoc_item.def_id, assoc_segment, bound)?;
         let result = LoweredAssoc::Term(def_id, args);
 
         if let Some(variant_def_id) = variant_resolution {

compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs

@@ -314,11 +314,10 @@ impl<'tcx> HirTyLowerer<'tcx> for FnCtxt<'_, 'tcx> {
         item_def_id: DefId,
         item_segment: &rustc_hir::PathSegment<'tcx>,
         poly_trait_ref: ty::PolyTraitRef<'tcx>,
-        _assoc_tag: ty::AssocTag,
     ) -> Result<(DefId, ty::GenericArgsRef<'tcx>), ErrorGuaranteed> {
         let trait_ref = self.instantiate_binder_with_fresh_vars(
             span,
-            // FIXME(mgca): this should be assoc const if that is the `kind`
+            // FIXME(mgca): `item_def_id` can be an AssocConst; rename this variant.
             infer::BoundRegionConversionTime::AssocTypeProjection(item_def_id),
             poly_trait_ref,
         );