lib.callPackages(With): guard against a repeated mistake #81713
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One other option could be to merge these functions and automatically choose the right of the two variants (single package or a set of them). |
| in | ||
| if lib.isDerivation pkgs then throw | ||
| "function callPackages called on a *single* derivation `${pkgs.name or "<unknown-name>"}`." | ||
| else lib.mapAttrs mkAttrOverridable pkgs; |
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Parenthetical to this PR but doing a mapAttrs over all of pkgs seems like a really bad idea for performance. Hadn't noticed that before.
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Typically callPackages is used on tiny sets, fortunately.
Is there a faster way? Even if it's very hacky, we can at least use it to measure potential performance benefit – estimate how much human work is worth putting into this.
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A quick nix-env -qa ... trace showed only a few larger sets, all under 100
trace: 28
trace: 34
trace: 43
trace: 43
trace: 88
trace: 93
(caveat is that this quick test recurses into a bit fewer sets than Hydra)
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I'll assume it's not bad enough to invest more time (of mine).
For example see the parent commit.
For example see the parent commit.
I tried some 8-second evaluation tasks on nixpkgs on this commit and its parent, and the performance impact didn't seem measurable (only a tiny bit more memory).