perlPackages.Po4a affects g++

[JohnAZoidberg]

Issue description

Adding perlPackages.Po4a changes which g++ is used.
I encountered it when trying to write a derivation which requires the po4a-translate command. But when I add perlPackages.Po4a to the nativeBuildInputs the C++ compiler is different and the project won't build anymore.
Can be reproduced in the nix-shell as well.

Steps to reproduce

$ readlink -f $(which g++)
/nix/store/w2px3blinprrzx6wva8x7m0l9l27jzj9-gcc-wrapper-7.4.0/bin/g++
$ nix-shell -p perlPackages.Po4a
$ readlink -f $(which g++)
/nix/store/y60j0zq2j50iaaqjn39i18hkhp277zfy-gcc-wrapper-7.4.0/bin/g++

Technical details

• system: "x86_64-linux"
• host os: Linux 5.0.7, NixOS, 19.09pre177249.dfd8f84aef1 (Loris)
• multi-user?: yes
• sandbox: yes
• version: nix-env (Nix) 2.2.2
• nixpkgs: /nix/store/vw34y7p1zml11w2cdsj4a6afgkj2w4pw-source

My version of NixOS is equivalent to this tree of nixpkgs-unstable.

[LnL7]

I don't think that's the problem, user-env-packages only affects nix-env/systemPackages. Without that nix-shell and builds are still affected by the propagated compiler (or other build tools).

[JohnAZoidberg]

How could I work around this? (In the context of using it as nativeBuildInputs)

[JohnAZoidberg]

The closure is (notice how there's no gcc):

$ nix-closure $(nix-build '<nixpkgs>' -A perlPackages.Po4a)
/nix/store/681354n3k44r8z90m35hm8945vsp95h1-glibc-2.27
/nix/store/7yjxqw8187sj0py0vixnnfwjprgq9m32-attr-2.4.48
/nix/store/dlqjzmrdlp3vipfwyfz2n39cpf1ad2j6-acl-2.2.53
/nix/store/baylddnb83lh45v3fz15ddhbpxbdb7m7-coreutils-8.31
/nix/store/7750im9ysip9hmc1j8xkcaqy6j14bhsr-perl-5.28.1
/nix/store/44marm0sy7lfisarzgfnxsjzvd12q1j2-perl5.28.1-SGMLSpm-1.1
/nix/store/5lyvydxv0w4f2s1ba84pjlbpvqkgn1ni-linux-headers-4.19.16
/nix/store/s3f5sqsm4mfigpkz6cmi99i24yng5msr-perl5.28.1-MIME-Charset-1.012.2
/nix/store/7g3li1crggcg36rn684zbxiva1i184sm-perl5.28.1-Unicode-LineBreak-2019.001
/nix/store/886w5d5zwg0p6ggbz5vwyk4aiqgsdzgw-perl5.28.1-TermReadKey-2.38
/nix/store/j4fz5m9si39qvns44zcwdya5zpdlhz58-perl5.28.1-Module-Build-0.4224
/nix/store/f5wl80zkrd3fc1jxsljmnpn7y02lz6v1-glibc-2.27-bin
/nix/store/qaybsxbkg4n19lfh2p59a3q6sgzi7ndn-perl5.28.1-Text-CharWidth-0.04
/nix/store/sr4253np2gz2bpha4gn8gqlmiw604155-glibc-2.27-dev
/nix/store/kpzpklf8d4dl16r2n5xzl6qapdf9636q-perl5.28.1-Text-WrapI18N-0.06
/nix/store/pjg2pmk1zh5l1cc3kb67xc68s4n9b0w4-perl5.28.1-gettext-1.07
/nix/store/yjkch3aia9ny4dq42dbcjrdwqb1y8c33-bash-4.4-p23
/nix/store/9pihd9jvw7xnvq3vsdz0h48f34q60vzi-perl5.28.1-po4a-0.47

When I force configure to ignore the wrong gcc it fails during the compilation with the same error as in #28748 (missing <stdlib.h>). I can't remove glibc in the inputs of my project since it's not there. But that must mean the glibc in the closure of perlPackages.Po4a is the problem.

I can build my derivation if I add just the binaries to the path:

  preConfigure = ''
    export PATH="${perlPackages.Po4a}/bin:$PATH"
  '';

[stale]

Thank you for your contributions.

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