pkgs/by-name: document toplevel argument restrictions #325262
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We've been bitten by this at least twice, let's make sure to write it down.
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| well as those added through the use of overlays will cause defaults to be | ||
| overwritten in a unexpected and hard-to-debug fashion. | ||
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| In case you're intending to write more flexible package expressions, consider |
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This is not by-name's mistake. This is about callPackage. Whenever people use callPackage they are affected.
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Agreed it's not by-name's mistake.
This also say it's because it's callPackage'd. I still think it's worth to write it down like this, because people tend to be too fancy with what they do in by-name, and restricting it only to packages defined in the top-level (without defaults) and to only boolean enable flags prevents this effectively.
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The main restriction with by-name is that you can't use a custom callPackage, there's nothing else that I know of affecting the override interface. Besides, there is an upcoming check to enforce moving to by-name when touching packages at the top-level, so this suggestion doesn't make sense.
Let's just drop the sentence and make the guidelines more explicit if needed.
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Please propose exact wording in a new PR.
| @@ -76,6 +76,17 @@ and override its value in [`pkgs/top-level/all-packages.nix`](../top-level/all-p | |||
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| ### Toplevel argument restrictions | |||
| The list of toplevel arguments should be restricted to packages defined in the | |||
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Well, technically nothing hinders someone of creating a package with the exact same name of a Boolean flag.
What about with-shell?
https://github.com/NixOS/nixpkgs/blob/nixos-24.05/pkgs/applications/misc/with-shell/default.nix
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Doesn't have any "non-package args", so don't understand the question.
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I am saying that with-shell is an existing package, and because of callPackage no one can use with-shell as a simple Boolean flag.
| @@ -76,6 +76,17 @@ and override its value in [`pkgs/top-level/all-packages.nix`](../top-level/all-p | |||
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| ``` | |||
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| ### Toplevel argument restrictions | |||
| The list of toplevel arguments should be restricted to packages defined in the | |||
| common nixpkgs package set, and simple `enable*` boolean flags. | |||
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Attributes of type string are employed to indicate options. Emacs expression accepts toolkit as "gtk", "motif", "athena"...
And Emacs is outside by-name.
We've been bitten by this at least twice, let's make sure to write it down.
finalAttrs.{pname,version}introducing overriding traps #310373 (comment)Things done
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