From 0f8caaf0bf17f010b419bfc2a7796436fb37f01d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thomas=20M=C3=BChlbacher?= <tmuehlbacher@posteo.net>
Date: Mon, 10 Jun 2024 23:22:00 +0200
Subject: [PATCH] build(nix): filter src to reduce useless rebuilds
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This in particular speeds up the dev/run/debug cycle for writing more
tests. Without this, the actual bcachefs-tools package will be rebuilt
by Nix all the time because of changes to files that are tracked by git.
Even when it's changes in parts that aren't relevant to that package
build such as `checks/*`.

Signed-off-by: Thomas Mühlbacher <tmuehlbacher@posteo.net>
---
 flake.nix | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/flake.nix b/flake.nix
index 963dee119..c95912c3e 100644
--- a/flake.nix
+++ b/flake.nix
@@ -58,6 +58,7 @@
         }:
         let
           inherit (builtins) readFile split;
+          inherit (lib) fileset;
           inherit (lib.lists) findFirst;
           inherit (lib.strings) hasPrefix removePrefix substring;
 
@@ -74,7 +75,17 @@
 
           commonArgs = {
             inherit version;
-            src = self;
+            src = fileset.toSource {
+              root = ./.;
+
+              fileset = fileset.difference (fileset.gitTracked ./.) (
+                fileset.unions [
+                  ./checks
+                  ./doc
+                  ./tests
+                ]
+              );
+            };
 
             env = {
               PKG_CONFIG_SYSTEMD_SYSTEMDSYSTEMUNITDIR = "${placeholder "out"}/lib/systemd/system";