nix whacks

Author: HyperfocusSurfer

content/nix_whacks.md

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+title = "Nix whacks"
+date = 2025-04-28
+[taxonomies]
+tags = ["nix"]
++++
+
+A loose collection of useful nix snippets.
+
+## Patch-in a PR while building a package
+
+Say, we want to include the [147th PR to done.fish](https://github.com/franciscolourenco/done/pull/147)
+
+* append `.diff` or `.patch` to the url, which will redirect you to [https://patch-diff.githubusercontent.com/raw/franciscolourenco/done/pull/147.diff](https://patch-diff.githubusercontent.com/raw/franciscolourenco/done/pull/147.diff)
+* pull and apply the patch via nix:
+
+```nix
+(fishPlugins.done.overrideAttrs (final: prev: {
+  patches = [(fetchpatch {
+    url = "https://patch-diff.githubusercontent.com/raw/franciscolourenco/done/pull/147.diff";
+    hash = "sha256-tIXVfXLSLwc54Z3HZcfwgGv1vEzAaBVNAjeq4vVNxNI=";
+  })];
+}))
+```
+
+[[Source](https://discourse.nixos.org/t/easiest-way-to-include-nixpkgs-pull-request/39307/3)]
+
+## Overriding non-trivial builders
+
+Default `overrideAttrs` is applied to the result of various `buildRustPackage`s and `buildGoModule`s, so if you want to override some builder-specific stuff (like `cargoHash`), you need to `override` the builder instead:
+
+```nix
+(tectonic-unwrapped.override (old: {
+  rustPlatform = old.rustPlatform // {
+    buildRustPackage = args: old.rustPlatform.buildRustPackage (args // {
+      # override src/cargoHash/buildFeatures here
+    });
+  };
+}))
+```
+
+[[Source](https://discourse.nixos.org/t/is-it-possible-to-override-cargosha256-in-buildrustpackage/4393/9)]