All faust software fails to build: impure path in link

[magnetophon]

Describe the bug

Any software that is compiled using faust, fails at the installPhase:

impure path `/tmp/faust2lv2.OOEUWy/dualMonoAmp.lv2/dualMonoAmp.so' used in link
collect2: error: ld returned 1 exit status

Presumably caused by these lines.

Similar issues:
#97420
#97520

To Reproduce
Steps to reproduce the behavior:

1. Check out a317361 or later.
2. run nix-env -f $NIXPKGS -iA magnetophonDSP.CharacterCompressor
3. get error.

Expected behavior
A clean install.

Metadata

• system: "x86_64-linux"
• host os: Linux 5.7.15, NixOS, 20.09pre242769.61525137fd1 (Nightingale)
• multi-user?: yes
• sandbox: yes
• version: nix-env (Nix) 2.3.7
• channels(bart): ""
• channels(root): "nixos-20.09pre242769.61525137fd1, nixos-hardware"
• nixpkgs: /nix/var/nix/profiles/per-user/root/channels/nixos

[magnetophon]

The offending line in the faust source is probably: https://github.com/grame-cncm/faust/blob/d747fd13a7668f1479ec4a3f0a045667ca36df1e/tools/faust2appls/faust2jaqt#L172

Most faust compile scripts have that line.

Would it make sense to patch mktemp?

[vcunat]

At a glance I'd think that this mktemp usage should be fine: #93560 (comment)

[vcunat]

I expect that script we have in wrapper gets confused by (re-)definition of $TMP.

[magnetophon]

@vcunat Thanks for having a look.

I expect that script we have in wrapper gets confused by (re-)definition of $TMP.

Why do you think that, and how do I fix it?

[vcunat]

Our latest wrapper code actually uses $TMP to detect tmpdir location... which might not be a good way now that I think of it; I haven't done any research, but mktemp is documented to use $TMPDIR which is a longer name and seems less likely to be clobbered like this.

[magnetophon]

@vcunat I tried to build with 441a7da (the latest unstable), which should include the commit you referred to, but I'm still getting the same issue.

Any ideas on how to fix it?

[magnetophon]

When I build 2a35f66 there is no problem anymore.
No idea what changed though.

[vcunat]

#93560 had been reverted. An improved version is planned (#97597) which most likely won't cause problems with faust (or elsewhere).

[magnetophon]

Thanks!