Point at overlapping impls when type annotations are needed

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

@@ -464,7 +464,7 @@ fn report_conflicting_impls(
 
 /// Recovers the "impl X for Y" signature from `impl_def_id` and returns it as a
 /// string.
-fn to_pretty_impl_header(tcx: TyCtxt<'_>, impl_def_id: DefId) -> Option<String> {
+crate fn to_pretty_impl_header(tcx: TyCtxt<'_>, impl_def_id: DefId) -> Option<String> {
     use std::fmt::Write;
 
     let trait_ref = tcx.impl_trait_ref(impl_def_id)?;