error[E0557]: feature has been removed
   --> /wrkdirs/usr/ports/www/firefox-esr/work/firefox-78.15.0/third_party/rust/packed_simd/src/lib.rs:202:41
    |
202 | #![cfg_attr(use_const_generics, feature(const_generics))]
    |                                         ^^^^^^^^^^^^^^ feature has been removed
    |
    = note: removed in favor of `#![feature(adt_const_params]` and `#![feature(generic_const_exprs)]`

https://github.com/rust-lang/packed_simd/commit/45d5347a0d2187c046a546a477d2a53111cd7713

--- third_party/rust/packed_simd/src/lib.rs.orig	2021-10-21 12:39:34 UTC
+++ third_party/rust/packed_simd/src/lib.rs
@@ -199,7 +199,7 @@
 //!   Numeric casts are not very "precise": sometimes lossy, sometimes value
 //!   preserving, etc.
 
-#![cfg_attr(use_const_generics, feature(const_generics))]
+#![cfg_attr(use_const_generics, feature(adt_const_params))]
 #![cfg_attr(use_const_generics, allow(incomplete_features, clippy::from_over_into))]
 #![feature(
     repr_simd,