From 3fd98e7fcb2fdc1b7699fd7de2bc83c67cf21c4a Mon Sep 17 00:00:00 2001
From: hyperfekt <git@hyperfekt.net>
Date: Wed, 8 Jun 2022 13:50:36 +0200
Subject: [PATCH] nixos/fish: fix completion generation for non-derivation
 packages

environment.systemPackages can include any package, which means it can
be a top-level store path that is not a derivation and thus will not
have a name attribute - their name is extracted from the path instead.
---
 nixos/modules/programs/fish.nix | 17 +++++++----------
 1 file changed, 7 insertions(+), 10 deletions(-)

diff --git a/nixos/modules/programs/fish.nix b/nixos/modules/programs/fish.nix
index 160adc0cad6d..657130aa1b11 100644
--- a/nixos/modules/programs/fish.nix
+++ b/nixos/modules/programs/fish.nix
@@ -258,16 +258,13 @@ in
             preferLocalBuild = true;
             allowSubstitutes = false;
           };
-          generateCompletions = package: pkgs.runCommand
-            "${package.name}_fish-completions"
-            (
-              {
-                inherit package;
-                preferLocalBuild = true;
-                allowSubstitutes = false;
-              }
-              // optionalAttrs (package ? meta.priority) { meta.priority = package.meta.priority; }
-            )
+          generateCompletions = package: pkgs.runCommandLocal
+            ( with lib.strings; let
+                storeLength = stringLength storeDir + 34; # Nix' StorePath::HashLen + 2 for the separating slash and dash
+                pathName = substring storeLength (stringLength package - storeLength) package;
+              in (package.name or pathName) + "_fish-completions")
+            ( { inherit package; } //
+              optionalAttrs (package ? meta.priority) { meta.priority = package.meta.priority; })
             ''
               mkdir -p $out
               if [ -d $package/share/man ]; then