Log 0.4.8 and 0.3.9 generation issue --cfg=atomic_cas

[ghost]

hey @acmcarther, not sure if that is problem of cargo raze or rules_rust but the recent dependency on log 0.3.9 fails to build. Example that indirectly depends on that log version is slogger or grpc-0.6.1 crates from crates.io.

The problem seems to lay that log-0.3.9 imports log-0.4.8 which core method set_logger depends on atomic operations that are flipped via atomic_cas cfg flag. That one doesn't seem to be passed on many platforms correctly during compilation time. (Tested on Ubuntu 18.04 and Arch Linux) .

Workaround is to force cfg flag with cargo raze.

[raze.crates.log.'0.4.8']
additional_flags = [
    "--cfg=atomic_cas"
]

Not sure if you or rules_rust are aware of this issue. That's why I am creating this post. Also for any other person dealing with similar problem as me.

[acmcarther]

Thanks for filing this.

Looks like Cargo sets this cfg on most platforms in their build.rs. This is something that's hard for me replicate in cargo-raze even with current build.rs support, because we lack the ability to plumb from build.rs stdout to attrs for the dependent crate('s BUILD rule).

#97 contains an info dump about how build script execution currently works wit cargo-raze. TL;DR: Not well.

I'll keep this open so that folks can find it.