rustc_coherence_is_core #1494
Description
Just as a heads up rust-lang/rust#94963 changed the way this kind of impls on builtin and foreign types are handled. Libcore now uses #![rustc_coherence_is_core] to allow impls on any builtin type without #[lang = "..."] and other sysroot crates use #[rustc_allow_incoherent_impl] on all impl items for non-local impls.
Originally posted by @bjorn3 in #1086 (comment)