[Pkg-rust-maintainers] Bug#1053953: rust-indexmap: please upgrade to v2

[Peter Green]

preliminary analysis.

upstream changelog:

https://github.com/bluss/indexmap/blob/master/RELEASES.md

nothing looks two scary

forward dependencies:

the new version of indexmap depends on the new version of hasbrown, and my attempts at relaxing have been
unsuccesful, so it looks like we will need to do hashbrown first.

reverse dependencies:

The reverse dependency situation looks pretty good in general, details of individual packages below.

btm - jonas package, already uses 2.x upstream.
precious - jonas package, already uses 2.x upstream.
python-maturin - non rust team package, has not bumped dependency upstream already rc buggy and not in testing
rust-carapace-spec-clap - already uses 2.x upstream, debian package has dependency with no upper limit.
rust-cargo - uses 2.x since upstream version 0.74, upstream made no code changes when bumping indexmap version.
rust-cbindgen - upstream has not bumped but preliminary tests don't show any issues.
rust-clap-3 - clap 3.x still uses indexmap 1 clap 4.x no longer uses indexmap, but that patch is too big to reasonablly backport. Preliminary tests with a bumped version seem ok.
rust-gimli - upstream is on 2.x and appears to have bumped the dependency with no code changes (there are code changes in the commit, but they appear to relate to other dependency changes)
rust-h2 - upstream git (not yet included in a release) is on 2.x and appears to have bumped the dependency with no code changes (there are code changes in the commit, but they appear to relate to other dependency changes)
rust-laurel - non rust team package, upstream bumped dependency with no code changes.
rust-petgraph - upstream already uses 2.x, debian package has no upper limit on dependency.
rust-plist - upstream already uses 2.x
rust-pyproject-toml - upstream already uses 2.x
rust-quick-junit - upstream already uses 2.x
rust-ron - upstream uses 2.x in the latest (semver-breaking) version. The dependency bump was made with no code changes (though there was a feature name change)
rust-ruma-common - upstream uses 2.x in the latest (semver-breaking) version. The dependency bump was made with no code changes
rust-serde-with - upstream depends optionally on both versions 1.x and 2.x of indexmap. Debian currently disables the latter, looks like it needs to switch to disabling the former.
rust-serde-yaml - upstream uses 2.x in the latest (semver-breaking) version. The dependency bump was made with no code changes (though there was a feature change)
rust-sqlx-core - upstream uses 2.x, debian package has no upper limit on version.
rust-toml-edit - upstream uses 2.x, debian package has no upper limit on version.
rust-tre-command - upstream has not bumped but preliminary tests don't show any issues.
rust-tree-sitter-cli - upstream has not bumped but preliminary tests don't show any issues.
rust-configparser - upstream has not bumped but preliminary tests don't show any issues.
rust-cookie-store - upstream has not bumped but preliminary tests don't show any issues.
rust-elsa - upstream has not bumped but preliminary tests don't show any issues.
rust-object - upstream dependency bumped with no code changes
rust-py03 - upstream allows both versions 1.x and 2.x debian package has no upper limit on version.
rust-rkyv - upstream has not bumped, tests pass after bumping dependency and adding std feature to it.
rust-schemars - upstream has features for both versions of indexmap, currently the indexmap2 feature is disabled, no rdeps seem to depend on the indexmap feature
rust-serde-json - upstream uses 2.x
rust-toml - upstream uses 2.x in the latest (semver-breaking) version. The dependency bump was made with no code changes
rust-toml-0.5 - upstream uses 2.x in the latest (semver-breaking) version. The dependency bump was made with no code changes
rust-toml-edit - upstream uses 2.x in the latest (semver-breaking) version. The dependency bump was made with no code changes
rust-tower - upstream has not bumped, test failures look no worse than before.