Comment by pornel
10 months ago
The change itself was very reasonable. They only missed the mark on how that change was introduced. They should have waited with it until the next Rust edition, or at least held back a few releases to give users of the one affected package time to update.
The change was useful, fixing an inconsistency in a commonly used type. The downside was that it broke code in 1 package out of 100,000, and only broke a bit of useless code that was accidentally left in and didn't do anything. One package just needed to delete 6 characters.
Once the new version of Rust was released, they couldn't revert it without risk of breaking new code that may have started relying on the new behavior, so it was reasonable to stick with the one known problem than potentially introduce a bunch of new ones.
But that is not how backwards compatibility works. You do not break user space. And user space is pretty much out of your control! As a provider of a dependency you do not get to play such games with your users. At least not, when those users care about reliability.