Rust 1.6 regression watch


#1

Rust 1.6 is scheduled to be released two weeks from now, on January 21. Sadly, there are an alarming number of regressions still. Below is the ‘state of the regressions’ for the 1.6 release. We need any help we can get tackling them: some require bisecting to figure out what is going on, some require simple patches to revert. If you want to take one, just speak up on the issue tracker, but note that these need to be completed soon and backported to the beta branch (January 18th is probably the deadline). A number of them are assigned to me, but I will happily relinquish them. Just let me know.

First, this one is a stable regression from 1.4 -> 1.5. Nobody is sure what happened here, but it would be great if we could fix it in 1.6:

Next the regressions introduced in 1.6 beta:

Finally, some 1.7 matters that need attention:

  • Not a regression, but an improvement to language evolution. There are now lints for ‘future-incompatible’ changes. For example the new public-private changes for RFC 136. These need to be more descriptive though, indicating why we are breaking code.

#2

The macro ICE was fixed in https://github.com/rust-lang/rust/pull/30708