Function emit_inline_always_target_feature_diagnostic 

pub(crate) fn emit_inline_always_target_feature_diagnostic<'a, 'tcx>(
    tcx: TyCtxt<'tcx>,
    call_span: Span,
    callee_def_id: DefId,
    caller_def_id: DefId,
    callee_only: &[&'a str],
)

Emit diagnostic for calls to #[inline(always)]-annotated functions with a #[target_feature] attribute where the caller enables a different set of target features.