Regression report stable-2016-08-16 vs. beta-2016-09-21

  • From: stable-2016-08-16
  • To: beta-2016-09-21


  • 6263 crates tested: 4112 working / 1826 broken / 17 regressed / 5 fixed / 303 unknown.


  • There are 14 root regressions
  • There are 17 regressions

Root regressions, sorted by rank:

Full report.

I’ve only looked through a few so far but they looked legit. This release is scheduled to go out next Thursday.


Most of them have to do with as_ref+String fallout. The odd one is nanomsg-sys, which is an ICE - not sure if it has been reported so far.

  • “failed to read X/Cargo.toml” - slog, vnrc, hal, pmem
  • ICE - nanomsg-sys
  • “type annotations required: cannot resolve” - gluon, zmtp, carp, crowbook, bins, aluminum
  • “the lifetime parameter 'a is not constrained by the impl trait, self type, or predicates” - colerr
  • rustc overflowed stack! - pentry, boiler


gluon is fixed in git.


@eddyb what is the deal with as_ref + String?


Explained in issue Lint against using generic conversion traits when concrete methods are available


@bluss Do you know which change broke as_ref + String?


I thought it was new From impl for String


Yes, and reported and subsequently closed.


zmtp at least doesn’t look like the same type inference error: "type annotations required: cannot resolve std::borrow::Cow<'_, str>: std::borrow::Borrow<_>"


The “failed to read X/Cargo.toml” errors are false positives due to crater’s inability to munge Cargo.toml workspaces usefully. This could become problematic for crater’s continued usefulness.


I can’t repro the nanomsg-sys ICE.


OK, so here’s a new summary:

  • colerr says “the lifetime parameter 'a is not constrained by the impl trait, self type, or predicates”. Caused by
  • gluon, zmtp, carp, crowbook, bins, aluminum all fail because of a new From impl on String.
  • I can’t reproduce the nanomsg-sys ICE!
  • pentry and boiler are both overflowing the stack. This was thought to be fixed by increasing the stack size to 16MB. It’s not clear why it isn’t. I can’t reproduce.


I can’t even repro the stack overflows inside of a container using crater’s docker image :frowning:


I’ve started a crater run to test the impact of reverting