Zero Hydra Failures towards 22.11 NixOS release

November 8, 2022

The end of November is near and that means NixOS will get a release soon. One of the late stages is Zero Hydra Failures phase: there everyone squashes most of known build failures in nixpkgs/master before branching off new 22.11 release. tracks the effort and has a few hints on how to locate all known build failures in various places. So far there is a few thousands build failures in nixpkgs/master.

I had a chance to fix zsnes build failure. As you can see it’s a trivial fix. And we need a lot of fixes like these. If you would like to help nixpkgs and upstream projects then please join the effort of fixing those! Thank you in advance :)

Below I’ll run through an example build fix in more detail.

I usually start from periodic builder against nixpkgs/master. There I pick most recent evaluation and navigate to Still failing jobs tab. From there I pick failing package I like and check the build log. Apart from the build log there is also a commit at which the package was built successully last time. That usually helps in bisection of exact commit that broke the package. Useful when you have no idea why the package is unhappy.

Let’s pick synfigstudio-1.5.1 as a broken example. It’s build failure is hiding in It’s last successful build is (Inputs tab says it’s 667199140080a656d0be0d9c91b4bbac8828959f upstream commit around end of September 2022).

Build log complains about missing intltoolize: installing './INSTALL' installing './COPYING' using GNU General Public License v3 file     Consider adding the COPYING file to the version control system     for your code, to avoid questions about which license your project uses
src/gui/ installing 'config/depcomp'
parallel-tests: installing 'config/test-driver'
autoreconf: Leaving directory '.'
*** No intltoolize found, please install the intltool package ***

Trying a trivial fix:

--- a/pkgs/applications/graphics/synfigstudio/default.nix
+++ b/pkgs/applications/graphics/synfigstudio/default.nix
@@ -103,6 +103,7 @@ stdenv.mkDerivation {
+    intltool
   buildInputs = [
$ nix build -f . synfigstudio

Proposed fix against nixpkgs as That was easy.

Now out of curiosity let’s see what previous change did break synfigstudio:

$ git clone
$ cd nixpkgs

$ git bisect start origin/master 667199140080a656d0be0d9c91b4bbac8828959f
Bisecting: 4429 revisions left to test after this (roughly 12 steps)
[25b3b9b1b2af029d1a6db918d8fdb5560724681b] Merge staging-next into staging

$ git bisect run nix build -f. synfigstudio
running  'nix' 'build' '-f.' 'synfigstudio'

commit 0734f54ef262ad642eec1166a416bae86779ed9f
Date:   Sun Sep 25 05:49:25 2022 +0300

    treewide: move pkg-config, autoreconfHook, intltool to nativeBuildInputs

    found with nixpkgs-lint

If we look at that patch it removed intltool from buildInputs (HOST depends) instead of moving it to nativeBuildInputs (BUILD depends):

--- a/pkgs/applications/graphics/synfigstudio/default.nix
+++ b/pkgs/applications/graphics/synfigstudio/default.nix
@@ -107,21 +107,20 @@ stdenv.mkDerivation {
   buildInputs = [
-    intltool

   enableParallelBuilding = true;

Simple bug downstream-only bug. Nothing to report upstream.

Have fun and happy fixing!