Make --target link arg non-local

[russelltg]

I'm running into a situation where I filter imported targets with CRATE_TYPES to not include cdylib libraries, but have an executable that depends on a cdylib. Since I'm cross-compiling using clang, it needs that --target flag to compile, but since that flag is only being set locally it doesn't work.

It's possible more flags should be set like this, but this is the one I was running into. Is this a supported usecase?

[jschwe]

Basically, you are hitting issue #413, correct?

From the issue:

Adding the argument to the global RUSTFLAGS has the side-effect of overriding any rustflags set via .cargo/config.toml, which may be unexpected, especially since it only happens in the cross-compiling with clang scenario.

Preferably I would like to solve the issue upstream, so that rustc automatically passes the --target parameter to clang when required. I already asked on zulip and there seems to be general support, but I haven't had time to work on it.

In the meantime (assuming you are on Linux), you could write a small bash script for your target platform like:

aarch64-linux-gnu-clang:

#!/usr/bin/env bash
clang  --target=aarch64-linux-gnu "${@}"

And then in corrosion call

corrosion_set_linker(your_target /path/to/aarch64-linux-gnu-clang)

Please note that the filename of the bash script should end with clang (or clang-XX, where XX is a version number e.g. 13 or 14 ), so that rustc can infer the linker type from the filename.

[russelltg]

Yes, for some reason I assumed my use case was niche enough and didn't look a ton for issues, thanks!

That's a reasonable workaround. What I did it manually set that flag as non local on all the targets that it uses. (basically a workaround to implement what this PR does)

I'll close this considering it's known and you're (very reasonably) not interested in a fix within corrosion.

Thanks!