Check target with rustc directly

[dbkr]

To avoid depending on rustup (at least when not cross-compiling)

Fixes element-hq/element-web#17885

[jryans]

Hmm, are there cases where people don’t have rustup? Oh is that what Homebrew installation does? Strange, I’ve never used rust without rustup… 😅

[dbkr]

yeah - one of our packagers just builds in a rust environment without rustup, so they had to patch the check out to make it work again (and also I'd installed homebrew rust without rustup but might have to go rustup now anyway if I want multiple toolchains)

[jryans]

Thanks for looking into this! I learned that people don't always use rustup, which was news to me. 😅

[taw00]

I'm the packager who tripped over this.

For context: packagers (me included) who build packages in the more traditional way (RPMs, DEBs, etc) avoid using upstream libraries, toolchains, and such as much as possible and instead make every effort to rely on OS supplied and vetted components. rustup is not included in, for example, RHEL, CentOS, and Fedora's OS-shipped rust build environments, for all the obvious reasons. If you are building in those environments, you wait for the OS vender to go through their process of vetting and blessing the language toolchain and their updates.

In an ideal, most secure, build environment, the build system would also have zero access to the internet and all components necessary for the build would be in place, curated, and available locally. Node makes this really REALLY challenging, but we (community packagers) make certain compromises. :)

I hope that helps give color to this particular variety of issue. Cheers. -todd

[TheJJ]

I'm another packager who tipped over this, building for Gentoo, I had also patched away the check, thanks for the proper fix.

I just depend on the system-installed rust version, so no rustup involved.

I can only second what @taw00 says, the node+rust+... ecosystems make it very challenging properly packaging things especially without internet access...