Rust Nightly is missing a library

[witchof0x20]

Describe the bug

As of rust nightly 2020-06-22, Rust nightly cannot find libz.so.1
This issue is not present in Rust nightly 2020-06-21.

To Reproduce
Steps to reproduce the behavior:

nix-shell -p rustup
rustup update nightly
rustup run nightly rustc

/home/jade/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/rustc: error while loading shared libraries: libz.so.1: cannot open shared object file: No such file or directory

Expected behavior
rustc works

Additional context
This also happens with rust nightly from https://github.com/mozilla/nixpkgs-mozilla

Notify maintainers
@Mic92

Metadata

• system: "x86_64-linux"
• host os: Linux 5.4.46, NixOS, 20.03.2262.2b417708c28 (Markhor)
• multi-user?: yes
• sandbox: no
• version: nix-env (Nix) 2.3.6
• channels(root): "nixos-20.03.2262.2b417708c28, nixpkgs-unstable-20.09pre221694.342eaba9ebb"
• channels(jade): ""
• nixpkgs: /nix/var/nix/profiles/per-user/root/channels/nixos

Maintainer information:

# a list of nixpkgs attributes affected by the problem
attribute:
# a list of nixos modules affected by the problem
module:

[Mic92]

We are currently using patchelf in rustup internally to set the elf interpreter. Looks like we need to extend this to also extend the RPATH to add zlib. If someone makes a PR, I will review it! Not sure when I would get to implement that myself.

[Mic92]

Here is where we add patchelf: https://github.com/NixOS/nixpkgs/blob/master/pkgs/development/tools/rust/rustup/0001-dynamically-patchelf-binaries.patch

[witchof0x20]

I'm working on a patch for this. This is definitely the issue, just need to find the right way to extend the RPATH. I have something replacing it with a path containing zlib, but that overwrites the existing $ORIGIN/../lib, which breaks it. I would like to verify what is setting $ORIGIN/../lib there but hardcoding it should provide an early fix

[witchof0x20]

Extending the RPATH seems not to have worked

$ patchelf --print-rpath ~/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/rustc
$ORIGIN/../lib:/nix/store/byijk75wjm55sjngzl2zls2hgrg49lal-zlib-1.2.11/lib
$ .rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/rustc
.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/rustc: error while loading shared libraries: libz.so.1: cannot open shared object file: No such file or directory

[witchof0x20]

I'm investigating patching the files in lib
This issue may have been introduced by rust-lang/rust#72696 so it's likely the new zlib dependency shows up in the LLVM libraries