Disallow duplicate indexes using constant evaluation

[pkhry]

Description

following a suggestion from here #628 (comment)

Notes

It seems that it's not possible to have a good error message this way, as format! in cant be used in constant_blocks, so string interpolation is not possible unless we pick up const_format and re-export it from the library.

[gui1117]

I was basing my PR on top of yours, so I re-opened it.

@bkchr if you like it we can merge it

[ggwpez]

This was actually a major change that we released as a patch... it broke the docs build here https://docs.rs/crate/polkadot-sdk/0.12.1/builds/1788762
cc @gui1117 @nkpar

Also there was no CHANGELOG entry here?

[ggwpez]

Since this is arguably a breaking fix, do you think patch is still fine?

[bkchr]

Since this is arguably a breaking fix, do you think patch is still fine?

Yes, before this invalid code was emitted.

[gui1117]

A fix should have been pushed for the crates in 2412, 2409 and 2407, maybe polkadot-sdk 0.12.1 is an earlier version? or some crates have been missed.

Because we released and yank versions, sorry for that, the automatic changelog missed, I manually added it.

EDIT: I think pallet-revive-eth-rpc is using a non-supported version of sc-network.
paritytech/polkadot-sdk#7437 (comment)

It is surprising, in polkadot-sdk 0.12.1, pallet-revive-eth-rpc is using a different sc-cli than in the workspace, they are using sc-cli v0.49.0 instead of sc-cli v0.50.0 that is used by all other crates.

sc-cli v0.49.0 is using sc-network v0.47.0 and this version has not been patched, apparently

We can patch sc-network v0.47.0 but I think the issue may actually be different: why is pallet-revive-eth-rpc using a different version for sc-cli ? Something seems wrong during the publish process

[serban300]

Since there hasn't been any error report from any customer could we just fix the docs and keep this release ?

Sorry, I thought this change wasn't major since it doesn't change any interface or structure. It just adds a check for duplicate indexes, which should prevent misusing the library.