nim_builder: fails to build package when config.nims is missing a line ending

[daylinmorgan]

Nixpkgs version

• Unstable (25.05)

Describe the bug

nim_builder adds the line switch("backend", "c") to config.nims, but if config.nims has no line-ending it makes incorrect syntax so package build fails.

Steps to reproduce

Update nimble in nixos to v.18.0 and use nix build.

Expected behaviour

build completes successfully

Screenshots

No response

Relevant log output

Running phase: unpackPhase
@nix { "action": "setPhase", "phase": "unpackPhase" }
unpacking source archive /nix/store/h578k9z8vpc2sdy00qwgvh7i1civzia4-source
source root is source
Running phase: patchPhase
@nix { "action": "setPhase", "phase": "patchPhase" }
Running phase: updateAutotoolsGnuConfigScriptsPhase
@nix { "action": "setPhase", "phase": "updateAutotoolsGnuConfigScriptsPhase" }
Running phase: configurePhase
@nix { "action": "setPhase", "phase": "configurePhase" }
generating config.nims
Running phase: buildPhase
@nix { "action": "setPhase", "phase": "buildPhase" }
build job 0: nim compile --define:git_revision_override=v0.18.0 --parallelBuild:8 --outdir:/nix/store/ml4qqrf587a5bx3z6n2wbshnaishs351-nimble-0.18.0/bin src/nimble
�[1m/build/source/config.nims(9, 38) �[0m�[31mError: �[0mexpression 'switch("backend", "c")' has no type (or is ambiguous)�[36m�[0m�[0m
build phase failed

Additional context

No response

System metadata

• system: "x86_64-linux"
• host os: Linux 6.13.7, NixOS, 25.05 (Warbler), 25.05.20250315.c80f6a7
• multi-user?: yes
• sandbox: yes
• version: nix-env (Lix, like Nix) 2.93.0-dev-pre20250318-6e6ff58 System type: x86_64-linux Additional system types: i686-linux, x86_64-v1-linux, x86_64-v2-linux, x86_64-v3-linux, x86_64-v4-linux Features: gc, signed-caches System configuration file: /etc/nix/nix.conf User configuration files: /home/daylin/.config/nix/nix.conf:/etc/xdg/nix/nix.conf:/home/daylin/.nix-profile/etc/xdg/nix/nix.conf:/nix/profile/etc/xdg/nix/nix.conf:/home/daylin/.local/state/nix/profile/etc/xdg/nix/nix.conf:/etc/profiles/per-user/daylin/etc/xdg/nix/nix.conf:/nix/var/nix/profiles/default/etc/xdg/nix/nix.conf:/run/current-system/sw/etc/xdg/nix/nix.conf Store directory: /nix/store State directory: /nix/var/nix Data directory: /nix/store/32siqmws3z1ivk3546ahfa1phavzyxwa-lix-2.93.0-dev-pre20250318-6e6ff58/share
• channels(root): "nixos-23.11"
• nixpkgs: /nix/store/alzxn3hjisc84hrlv44x6hni48crww26-source

Notify maintainers

@ehmry

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