Nixpkgs version

• Unstable (25.11)

Steps to reproduce

nix-build -A libtins on latest unstable.

Can Hydra reproduce this build failure?

Yes, Hydra can reproduce this build failure.

Link to Hydra build job

https://hydra.nixos.org/build/309029939

Relevant log output

> CMake Error at CMakeLists.txt:1 (CMAKE_MINIMUM_REQUIRED):
       >   Compatibility with CMake < 3.5 has been removed from CMake.
       >
       >   Update the VERSION argument <min> value.  Or, use the <min>...<max> syntax
       >   to tell CMake that the project requires at least <min> but has been updated
       >   to work with policies introduced by <max> or earlier.
       >
       >   Or, add -DCMAKE_POLICY_VERSION_MINIMUM=3.5 to try configuring anyway.

Additional context

Another instance of #445447

System metadata

• system: "x86_64-linux"
• host os: Linux 6.12.49, NixOS, 25.11 (Xantusia), 25.11.20251002.7df7ff7
• multi-user?: yes
• sandbox: yes
• version: nix-env (Nix) 2.28.5
• nixpkgs: /nix/store/9v6qa656sq3xc58vkxslqy646p0ajj61-source

Notify maintainers

@fdns

Note for maintainers: Please tag this issue in your pull request description. (i.e. Resolves #ISSUE.)

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• I assert that this is not a duplicate of an existing issue.
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