Switching to opt-level=z on i686-windows-msvc triggers STATUS_ACCESS_VIOLATION

[dignifiedquire]

I have a crate which compiles and tests fine, but as soon as I switch opt-level=z it triggers STATUS_ACCESS_VIOLATION in some tests, but only on the windows targets. Tested on

• nightly-2019-11-06
• nightly-2019-12-20

The corresponding log outputs can be found here https://ci.appveyor.com/project/dignifiedquire/deltachat-core-rust/builds/29699168
and the code chatmail/core#1087

I am sorry I don't have a more reduced testcase, but I am quite clueless on how to debug this tbh.

[dignifiedquire]

Tested on windows x86_64, no issues present

[Brooooooklyn]

napi-rs/napi-rs#297 same issue here

[hameerabbasi]

As this is:

• Unsound
• A tier 1 platform
• Occurs on working code

we're assigning P-critical. See the wg-prioritization discussion.

[jyn514]

Is this a regression in 1.48? Could you test on 1.47 and see if the same issue happens there?

[Brooooooklyn]

Tested 1.36.0 ~ 1.48.0, all these versions occurred this bug.