assertion failed: eps.windows(2).all(|w| w[0].cmp(self, &w[1]) != Ordering::Greater)

[jedisct1]

Got an ICE while compiling the protobuf crate with that recent snapshot: rustc 1.15.0-nightly (28d6623bc 2016-12-03) on arm.

thread 'rustc' panicked at 'assertion failed: eps.windows(2).all(|w| w[0].cmp(self, &w[1]) != Ordering::Greater)', /buildslave/rust-buildbot/slave/nightly-dist-rustc-cross-host-linux/build/src/librustc/ty/context.rs:1525

Meta

rustc --version --verbose:

rustc 1.15.0-nightly (28d6623bc 2016-12-03)
binary: rustc
commit-hash: 28d6623bccf8f7e9a40a47895df75dd9ef2619da
commit-date: 2016-12-03
host: arm-unknown-linux-gnueabihf
release: 1.15.0-nightly
LLVM version: 3.9

Backtrace: https://gist.github.com/f7ea7c27e5acb684140d2a5227621617

[nikomatsakis]

triage: P-high

[pnkfelix]

/me is super-weirded out by the fact that the panic message is claiming that the assertion is arising from within librustc/ty/context.rs; I'm pretty sure there's never been any code there that looks anything like eps.windows(2).all(|w| w[0].cmp(self, &w[1]). Is that mismatch potentially a sign of broken source span information (e.g. arising from macro expansion)?

[Badel2]

I have this issue when compiling anything, even an empty project. As far as I can tell, it wasn't present in nightlies 2217bd7 2016-11-25 and 1c44857 2016-11-28

thread 'rustc' panicked at 'assertion failed: eps.windows(2).all(|w| w[0].cmp(self, &w[1]) != Ordering::Greater)', /buildslave/rust-buildbot/slave/nightly-dist-rustc-cross-host-linux/build/src/librustc/ty/context.rs:1525

I tried to run with RUST_BACKTRACE=1 and it took 10 minutes (it takes maybe 1 second without). Backtrace: https://gist.github.com/Badel2/9d0f9245fadca1505042dd4af4ef553a

root@localhost:~# rustc --version --verbose
rustc 1.15.0-nightly (daf8c1dfc 2016-12-05)
binary: rustc
commit-hash: daf8c1dfce3b448fc581cc319f64632ec22bd0e1
commit-date: 2016-12-05
host: armv7-unknown-linux-gnueabihf
release: 1.15.0-nightly
LLVM version: 3.9

Update: I tried more nightly versions and the first one to crash is rustc 1.15.0-nightly (908dba0 2016-12-01). The line number is slightly different this time.

thread 'rustc' panicked at 'assertion failed: eps.windows(2).all(|w| w[0].cmp(self, &w[1]) != Ordering::Greater)', /buildslave/rust-buildbot/slave/nightly-dist-rustc-cross-host-linux/build/src/librustc/ty/context.rs:1544

[arielb1]

I can't reproduce this. What configuration are you using?

Reproduced using an armel rustc and compiling a trivial file.