Kilian's homepage and public feed Zola 2026-08-20T00:00:00+00:00 https://kilko.de/tags/nixpkgs/atom.xml 2026-08-20T00:00:00+00:00 2026-08-20T00:00:00+00:00 Unknown https://kilko.de/feed/til/nix-assert-versionolder/ <p>Sometimes you have to override a specific package with something that's newer than what's available in nixpkgs. Often times – if you're me at least – you'll forget having done that later and will keep the override on a then older version than what's available in nixpkgs. In that case, it can make sense to do the following so nix will fail your build once the package advances enough.</p> <pre class="giallo z-code"><code data-lang="nix"><span class="giallo-l"><span class="z-variable">package</span><span class="z-invalid z-illegal"> =</span></span> <span class="giallo-l"><span class="z-invalid z-illegal"> assert</span><span class="z-variable"> lib</span><span class="z-keyword">.</span><span class="z-variable">assertMsg</span><span> (</span><span class="z-variable">lib</span><span class="z-keyword">.</span><span class="z-variable">versionOlder</span><span class="z-variable"> pkgs</span><span class="z-keyword">.</span><span class="z-variable">fosrl-newt</span><span class="z-keyword">.</span><span class="z-variable">version</span><span class="z-punctuation z-definition z-string"> &quot;</span><span class="z-string">1.16.0</span><span class="z-punctuation z-definition z-string">&quot;</span><span>)</span></span> <span class="giallo-l"><span class="z-punctuation z-definition z-string"> &quot;</span><span class="z-string">nixpkgs now ships fosrl-newt &gt;= 1.16.0 - remove this override</span><span class="z-punctuation z-definition z-string">&quot;</span><span class="z-invalid z-illegal">;</span></span> <span class="giallo-l"><span class="z-variable"> pkgs</span><span class="z-keyword">.</span><span class="z-variable">fosrl-newt</span><span class="z-keyword">.</span><span class="z-variable">overrideAttrs</span><span> (</span><span class="z-variable z-parameter z-function">old</span><span>:</span><span class="z-keyword"> rec</span><span> {</span></span> <span class="giallo-l"><span class="z-comment"> #</span><span class="z-comment"> ...</span></span> <span class="giallo-l"><span> }</span><span>)</span><span class="z-invalid z-illegal">;</span></span></code></pre>