[Pkg-rust-maintainers] Bug#1009667: rust-heck - new upstream release 0.4

[peter green]

Package: rust-heck

A new version of rust-cbindgen was recently uploaded, with a dependency on heck 0.4,
debian currently has 0.3. It would almost certainly be possible to patch cbindgen
to use heck 0.3 but I'm wondering if it makes more sense to upgrade heck.

The main changes in heck 0.4 are they renamed a bunch of stuff and they made
unicode support optional. I don't think these changes are significant enough
to justify packaging multiple versions of heck in parallel.

I started looking at the reverse dependencies of heck, all of them have fixes
upstream but in one case the upstream fix has not been included in a release
and in other cases the new upstream releases have semver bumps that would
open large dependency cans of worms. So it looks to me like patching is
likely the most reasonable approach in most cases to get the heck transition
to complete in a reasonable time.

rust-heck 0.3 -> 0.4
   rust-enum-as-inner 0.3 -> 0.4
     rust-trust-dns-proto no rdeps, already broken, not in testing
   rust-glib-macros fixed upstream, patching ( 91220bd0f31abe5d8ae3ac35aa4913664637ec83 ) seems like the best approach to avoid entangling the heck transition with a gtk stack transition
   rust-gtk3-macros fixed upstream, patching ( b74649ac901b284ac619ff40f8a16723fa72f653 ) seems like the best approach to avoid entangling the heck transition with a gtk stack transition
   rust-gtk4-macros fixed upstream, patching ( d0a6adb7a3ef5acc2d9fce7df8c16770b8a04f0a )seems like the best approach to avoid entangling the heck transition with a gtk stack transition
   rust-structopt-derive fixed in upstream git ( 2736281a647cecb23ae1c17bbaf625b18ebf4b38 ) , but not released, apply as patch.
   rust-strum-macros fixed upstream but updating opens up a dependency can of worms, patching ( fb88d04dcfb2eb2ba63c4f6dd924afed96d5b2f7seems ) the most sensible approach
   rust-system-deps patching (72af87c58bd92456218d5877eb9513c36810547e )seems like the best approach to avoid entangling the heck transition with a gtk stack transition
   rust-wasm-bindgen-webidl already broken and not in testing, see https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1007026

Anyone have any comments/objections before I go ahead and start working on this?