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treewide: use lib.systems.equals when comparing elaborated systems#319552

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Kranzes:lib.systems.equals
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treewide: use lib.systems.equals when comparing elaborated systems#319552
Kranzes wants to merge 1 commit intoNixOS:masterfrom
Kranzes:lib.systems.equals

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@Kranzes Kranzes commented Jun 13, 2024

Description of changes

nixpkgs/lib/systems/default.nix

Lines 30 to 46 in 3f84a27

/**
Elaborated systems contain functions, which means that they don't satisfy
`==` for a lack of reflexivity.
They might *appear* to satisfy `==` reflexivity when the same exact value is
compared to itself, because object identity is used as an "optimization";
compare the value with a reconstruction of itself, e.g. with `f == a: f a`,
or perhaps calling `elaborate` twice, and one will see reflexivity fail as described.
Hence a custom equality test.
Note that this does not canonicalize the systems, so you'll want to make sure
both arguments have been `elaborate`-d.
*/
equals =
let removeFunctions = a: filterAttrs (_: v: !isFunction v) a;
in a: b: removeFunctions a == removeFunctions b; 

nix-repl> (lib.systems.elaborate { system = "x86_64-linux"; }) ==  (lib.systems.elaborate { config = "x86_64-unknown-linux-gnu"; })
false

nix-repl> lib.systems.equals (lib.systems.elaborate { system = "x86_64-linux"; }) (lib.systems.elaborate { config = "x86_64-unknown-linux-gnu"; })
true

nix-repl> lib.systems.equals (lib.systems.elaborate { system = "x86_64-linux"; }) stdenv.buildPlatform
true

nix-repl> (lib.systems.elaborate { system = "x86_64-linux"; }) == stdenv.buildPlatform
false

nix-repl> lib.systems.equals (lib.systems.elaborate { system = "x86_64-linux"; }) stdenv.buildPlatform
true

Things done

  • Built on platform(s)
    • x86_64-linux
    • aarch64-linux
    • x86_64-darwin
    • aarch64-darwin
  • For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
    • sandbox = relaxed
    • sandbox = true
  • Tested, as applicable:
  • Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
  • Tested basic functionality of all binary files (usually in ./result/bin/)
  • 24.11 Release Notes (or backporting 23.11 and 24.05 Release notes)
    • (Package updates) Added a release notes entry if the change is major or breaking
    • (Module updates) Added a release notes entry if the change is significant
    • (Module addition) Added a release notes entry if adding a new NixOS module
  • Fits CONTRIBUTING.md.

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@github-actions github-actions bot added 6.topic: python Python is a high-level, general-purpose programming language. 6.topic: haskell General-purpose, statically typed, purely functional programming language 6.topic: qt/kde Object-oriented framework for GUI creation 6.topic: kernel The Linux kernel 6.topic: rust General-purpose programming language emphasizing performance, type safety, and concurrency. 6.topic: golang Go is a high-level general purpose programming language that is statically typed and compiled. 6.topic: ruby A dynamic, open source programming language with a focus on simplicity and productivity. 6.topic: vim Advanced text editor 6.topic: stdenv Standard environment 6.topic: nodejs Node.js is a free, open-source, cross-platform JavaScript runtime environment 6.topic: TeX Issues regarding texlive and TeX in general 6.topic: lua Lua is a powerful, efficient, lightweight, embeddable scripting language. 6.topic: systemd Software suite that provides an array of system components for Linux operating systems. labels Jun 13, 2024
@ofborg ofborg bot added 10.rebuild-darwin: 0 This PR does not cause any packages to rebuild on Darwin. 10.rebuild-linux: 0 This PR does not cause any packages to rebuild on Linux. labels Jun 13, 2024
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Kranzes commented Jun 13, 2024

This is not the right solution, this destroys eval performance. We need to re-create this PR #238331.

@Kranzes Kranzes closed this Jun 13, 2024
@eclairevoyant eclairevoyant mentioned this pull request Mar 16, 2025
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6.topic: golang Go is a high-level general purpose programming language that is statically typed and compiled. 6.topic: haskell General-purpose, statically typed, purely functional programming language 6.topic: kernel The Linux kernel 6.topic: lua Lua is a powerful, efficient, lightweight, embeddable scripting language. 6.topic: nodejs Node.js is a free, open-source, cross-platform JavaScript runtime environment 6.topic: python Python is a high-level, general-purpose programming language. 6.topic: qt/kde Object-oriented framework for GUI creation 6.topic: ruby A dynamic, open source programming language with a focus on simplicity and productivity. 6.topic: rust General-purpose programming language emphasizing performance, type safety, and concurrency. 6.topic: stdenv Standard environment 6.topic: systemd Software suite that provides an array of system components for Linux operating systems. 6.topic: TeX Issues regarding texlive and TeX in general 6.topic: vim Advanced text editor 10.rebuild-darwin: 0 This PR does not cause any packages to rebuild on Darwin. 10.rebuild-linux: 0 This PR does not cause any packages to rebuild on Linux.

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