_multioutPropagateDev(): can't set propagatedBuildOutputs with __structuredAttrs

[SomeoneSerge]

Describe the bug

Steps To Reproduce

❯ nix-build << \EOF

test-structured-multiple-outputs.nix
with import <nixpkgs> { };

stdenv.mkDerivation {
  pname = "structured-multiple-outputs";
  version = "0.0.1";
  __structuredAttrs = true;
  outputs = [
    "out"
    "a"
    "b"
    "c"
  ];
  dontUnpack = true;
  postInstall = ''
    for output in $(getAllOutputNames) ; do
      mkdir "''${!output}"
    done
  '';
  propagatedBuildOutputs = [
    "a"
    "b"
    "c"
  ];
}
EOF
❯ cat result/nix-support/propagated-build-inputs 
 /nix/store/c39a0kg4fazhc80zfrh8zq7ryc8hc577-structured-multiple-outputs-0.0.1-a

Expected behavior

❯ cat result/nix-support/propagated-build-inputs 
 /nix/store/vj1xb9gm2miy36mkzhg5man4b0qfq48r-structured-multiple-outputs-0.0.1-a /nix/store/72h5ba19ln4awnsyjd2m0srhny4aqfcs-structured-multiple-outputs-0.0.1-b /nix/store/aifzdh9si8qr59rwx1g89z6z6yz5pvgq-structured-multiple-outputs-0.0.1-c

The above was obtained with:

  # _multioutPropagateDev() currently expects a space-separated string rather than an array
  preFixup = ''
    export propagatedBuildOutputs="''${propagatedBuildOutputs[@]}"
  '';

Notify maintainers

CC maybe @vcunat @Artturin ?

Metadata

Please run nix-shell -p nix-info --run "nix-info -m" and paste the result.

❯ nix flake metadata nixpkgs
Resolved URL:  path:/nix/store/dydg48djlykksz8cxq0xjplyxpa9pvf4-source?lastModified=1718160348&narHash=sha256-9YrUjdztqi4Gz8n3mBuqvCkMo4ojrA6nASwyIKWMpus%3D&rev=57d6973abba7ea108bac64ae7629e7431e0199b6
Locked URL:    path:/nix/store/dydg48djlykksz8cxq0xjplyxpa9pvf4-source?lastModified=1718160348&narHash=sha256-9YrUjdztqi4Gz8n3mBuqvCkMo4ojrA6nASwyIKWMpus%3D&rev=57d6973abba7ea108bac64ae7629e7431e0199b6
Description:   A collection of packages for the Nix package manager
Path:          /nix/store/dydg48djlykksz8cxq0xjplyxpa9pvf4-source
Revision:      57d6973abba7ea108bac64ae7629e7431e0199b6
Last modified: 2024-06-12 02:45:48

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