Looks like it has already been fixed by #418939, but did not yet make it into the unstable branch.

Nixpkgs version

• Unstable (25.11)

Steps to reproduce

nix-build '<nixpkgs>' -I nixpkgs=channel:nixos-unstable --arg crossSystem '{ config = "aarch64-unknown-linux-gnu"; }' -A perl

Relevant log output

Checking type fd_set ... found
Checking whether fd_set has fds_bits ... no
Checking whether siginfo_t has si_fd ... yes
Checking for dirfd ... found
Checking for fdclose ... missing
...
In file included from perl.h:49,
                 from miniperlmain.c:57:
xconfig.h:114:3: error: invalid preprocessing directive #HAS_FDOPENDIR
  114 | # HAS_FDOPENDIR         /**/
      |   ^~~~~~~~~~~~~

System metadata

• system: "x86_64-linux"
• host os: Linux 6.15.1, NixOS, 25.05 (Warbler), 25.05.803579.70c74b02eac4
• multi-user?: yes
• sandbox: yes
• version: nix-env (Nix) 2.28.3
• channels(root): "nixos-25.05, nixos-hardware"
• nixpkgs: /nix/store/gdz4yp5sjq3b1q0g9ad9hicqsx1alvif-nixos-25.05/nixos

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