Auto merge of #129777 - nnethercote:unreachable_pub-4, r=Urgau

Add `unreachable_pub`, round 4

A follow-up to #129732.

r? `@Urgau`

compiler/rustc_trait_selection/src/traits/coherence.rs

@@ -54,7 +54,7 @@ pub fn add_placeholder_note<G: EmissionGuarantee>(err: &mut Diag<'_, G>) {
     );
 }
 
-pub fn suggest_increasing_recursion_limit<'tcx, G: EmissionGuarantee>(
+pub(crate) fn suggest_increasing_recursion_limit<'tcx, G: EmissionGuarantee>(
     tcx: TyCtxt<'tcx>,
     err: &mut Diag<'_, G>,
     overflowing_predicates: &[ty::Predicate<'tcx>],