Description

Due to recent changes in rustc regarding the interaction between mem::uninitialized and ManuallyDrop (basically the later no longer being a union), many crates are now directly having the code path nullified by LLVM, getting illegal instruction because they are treated as dead code.

Your Environment

rustc 1.38.0-nightly (78ca1bda3 2019-07-08)
binary: rustc
commit-hash: 78ca1bda3522b14bc0336bc01dd1d49fdba2cda7
commit-date: 2019-07-08
host: x86_64-unknown-linux-gnu
release: 1.38.0-nightly
LLVM version: 8.0

[profile.dev]
opt-level = 1

Causes found so far

• x11-rs issue, with additional context about the compiler change. Pending PR.
• Outdated versions of crossbeam::queue seems to cause this issue as well. Patches for specs, amethyst.