Rollup merge of #102786 - compiler-errors:no-tuple-candidate, r=lcnr

Remove tuple candidate, nothing special about it

r? `@lcnr` you mentioned this during the talk you gave i think

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

@@ -1021,7 +1021,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         let self_ty = self.infcx().shallow_resolve(obligation.self_ty().skip_binder());
         match self_ty.kind() {
             ty::Tuple(_) => {
-                candidates.vec.push(TupleCandidate);
+                candidates.vec.push(BuiltinCandidate { has_nested: false });
             }
             ty::Infer(ty::TyVar(_)) => {
                 candidates.ambiguous = true;

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

@@ -126,8 +126,6 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                 let data = self.confirm_const_destruct_candidate(obligation, def_id)?;
                 ImplSource::ConstDestruct(data)
             }
-
-            TupleCandidate => ImplSource::Tuple,
         };
 
         if !obligation.predicate.is_const_if_const() {

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

@@ -1562,7 +1562,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         };
 
         // (*) Prefer `BuiltinCandidate { has_nested: false }`, `PointeeCandidate`,
-        // `DiscriminantKindCandidate`, `ConstDestructCandidate`, and `TupleCandidate`
+        // `DiscriminantKindCandidate`, `ConstDestructCandidate`
         // to anything else.
         //
         // This is a fix for #53123 and prevents winnowing from accidentally extending the
@@ -1583,8 +1583,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                 BuiltinCandidate { has_nested: false }
                 | DiscriminantKindCandidate
                 | PointeeCandidate
-                | ConstDestructCandidate(_)
-                | TupleCandidate,
+                | ConstDestructCandidate(_),
                 _,
             ) => true,
             (
@@ -1592,8 +1591,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                 BuiltinCandidate { has_nested: false }
                 | DiscriminantKindCandidate
                 | PointeeCandidate
-                | ConstDestructCandidate(_)
-                | TupleCandidate,
+                | ConstDestructCandidate(_),
             ) => false,
 
             (ParamCandidate(other), ParamCandidate(victim)) => {