Function rustc_resolve::macros::sub_namespace_match

pub(crate) fn sub_namespace_match(
    candidate: Option<MacroKind>,
    requirement: Option<MacroKind>,
) -> bool

Macro namespace is separated into two sub-namespaces, one for bang macros and one for attribute-like macros (attributes, derives). We ignore resolutions from one sub-namespace when searching names in scope for another.