Rust unit tests fail in release about blst

[dot-asm]

I count it as resolved. One might be able to argue that failure might be caused by something in blst that can be formally viewed as ambiguous in respect to some comma in language specification, but odds are not in favour, since a whole bunch of compilers show no problem. But I'll keep my eyes open...

[dot-asm]

Now travis-ci tests with --release, and it's all green. It's using stable rustc 1.44.1 and whatever C compiler there is. There is some gcc on Linux platforms, some clang on MacOS and some msvc on Windows.

It's now possible to effectively separate cc flags by pre-building libblst.a manually. In order to do that, go to bindings/rust, execute [say] ../../build.sh -O1, cargo clean [just in case] and finally cargo test --release. This is assuming that you removed opt-level=2...

[paulhauner]

Turns out I can get those tests to pass if I add this to the Cargo.toml:

[profile.bench]
opt-level = 2

I'll make a branch which sets these values so it can compile inside Lighthouse, then make a PR for you to review.

[paulhauner]

Tt turns out I need to set the global Lighthouse build to opt-level = 2, which is a shame.

I imagine it's possible to run with opt-level = 3 (the default) if we can figure out what's causing the bad behaviour. I suspect it'll be inside an unsafe block.

I need to move on now, but I might come back to this and have a poke around.

[dot-asm]

What's your rustc --version? And what's your cc --version? Usually variance on optimization level is indication of a compiler bug. Note that there are two compilers involved and it can be bug in either... We probably should add an option to use pre-compiled libblst.a so that one can separate C and Rust flags for fine-grained troubleshooting... One should also wonder if CFLAGS environment variable have effect on cc-rs and if so, if you have one set... Try even env CC=clang cargo test --release.

Just in case, excessive questions mean that we can't reproduce the problem...

[paulhauner]

What's your rustc --version? And what's your cc --version?

Sorry for not providing this earlier.

rustc --version
rustc 1.44.1 (c7087fe00 2020-06-17)

cc --version
cc (GCC) 10.1.0
Copyright (C) 2020 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

[dot-asm]

cc (GCC) 10.1.0

I bet this is the problem:-) Either way, I've limited cc optimization level to 2 in build.rs.