Perfecting Rust Packaging

[brson]

@jauhien

System wide LLVM: it worked for us, but now we've switched to shipping shared LLVM libraries only, so we need support for linking with shared libs from Rust upstream /see rust-lang/rust#27937/.

Noted.

@jauhien

Installation of multiple rusts. It works for us without multirust, the only thing we need is the ability to install rust libs/binaries to custom dirs. There is one bug in the rust installer that we temporary fix with patch.

Huh. I'm sad to say I've looked at this patch for a while and still don't see what the bug is. Can you explain in more detail what the patch is working around? Is there a filed issue? (I know that --libdir has always been in some state of broken)

@jauhien

Cargo/rust infrastructure support in general: the main problem is how to make cargo use system libraries during production build (it fetches everything and uses fetched versions). This + not very clean linking model (or may be I just do not understand it well enough) makes shipping cargo based packages in gentoo at the moment near impossible. The ideal solution would be if there existed some 'production' mode for cargo when it is used just as a nice build system and uses only packages already installed in the system. If no necessary package is found it should just fail.

This is a common theme!

cc @alexcrichton

@jauhien

-Werror switched on during Rust build, ideally it would be good to have a possibility to switch it off (I'm just sedding mk scripts at the moment)

Ah, interesting point. I've opened an issue: Option to control -Werror in makefiles · Issue #28599 · rust-lang/rust · GitHub

@jauhien

Additional libraries suffix. At the moment I'm sedding with sed -i -e "s/CFG_FILENAME_EXTRA=.*/CFG_FILENAME_EXTRA=${postfix}/" mk/main.mk, it would be good to have some switch in the build system to do this (it is necessary for the possibility of relible side by side istallation of libs).

Ah, yes, that makes sense. Although we (try to) tie that extra bit to the version number. Perhaps we're just not capturing enough metadata to differentiate the versions of Rust you are installing together?

In fact, the code looks wrong. It's hashing an undefined variable...

Would hashing the version number as intended be enough to distinguish your sxs installs?

Edit: After investigation, this does actually hash the version number correctly before CFG_RELEASE is defined. I don't understand why offhand.