fix: collator selection v2 storage migration

[wischli]

Description

Fixes unmentioned breaking storage change in collator selection pallet by manually backporting an improved version of their fix.

Unfortunately, we bump the storage version here higher than the max version of the [email protected] such that try-runtime throws an error:

[2024-06-06T09:06:24Z ERROR runtime::frame-support] CollatorSelection: On chain storage version StorageVersion(2) doesn't match current storage version StorageVersion(1).

This will lead to unsuccessful try-runtime CI in our codebase until we upgrade to SDK v1.11.0. I still prefer this over applying the migration and staying at v1. WDYT @lemunozm @mustermeiszer?

Checklist:

• I have added Rust doc comments to structs, enums, traits and functions
• I have made corresponding changes to the documentation
• I have performed a self-review of my code
• I have added tests that prove my fix is effective or that my feature works

[lemunozm]

we bump the storage version here higher than the max version of the [email protected] such that try-runtime throws an error

As a workaround, can we later force v1 again with a new migration?

[wischli]

we bump the storage version here higher than the max version of the [email protected] such that try-runtime throws an error

As a workaround, can we later force v1 again with a new migration?

Then, we could also just not bump the storage version with this migration.

[lemunozm]

Does that make sense to you? Or could it lead to future issues? I guess when the correct 1.11 migration enters, then it will migrate 0 entries and everything will work

[wischli]

Does that make sense to you? Or could it lead to future issues? I guess when the correct 1.11 migration enters, then it will migrate 0 entries and everything will work

Since we drain the Candidates storage here, re-applying this migrations shouldn't do any harm. So I am also fine with going the path of applying the migration in an unchecked fashion in which we don't bump the storage version. Will push after lunch!

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 46.68%. Comparing base (e1bad5f) to head (952f8f6).
Report is 9 commits behind head on polkadot-v1.7.2.

Additional details and impacted files

@@                 Coverage Diff                 @@
##           polkadot-v1.7.2    #1862      +/-   ##
===================================================
- Coverage            46.93%   46.68%   -0.26%     
===================================================
  Files                  166      167       +1     
  Lines                13048    13121      +73     
===================================================
+ Hits                  6124     6125       +1     
- Misses                6924     6996      +72     

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[lemunozm]

Great! And we do no longer get errors from try-runtime

[lemunozm]

LGTM!

[lemunozm]

Thanks for your good research about this topic

[lemunozm]

@wischli does it mean this PR is no longer needed?

[wischli]

@wischli does it mean this PR is no longer needed?

We still need the migration but the diff is now only 3 lines :)