From 1ceba9367c27ec3586766df242081ef55ba56f66 Mon Sep 17 00:00:00 2001
From: Valentin Gagarin <valentin@gagarin.work>
Date: Wed, 18 Sep 2024 21:54:02 +0200
Subject: [PATCH] meson/setup-hook.sh: make build directory configurable

---
 doc/hooks/meson.section.md          | 10 ++++++++++
 pkgs/by-name/me/meson/setup-hook.sh |  6 ++++--
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/doc/hooks/meson.section.md b/doc/hooks/meson.section.md
index 3a7fb5032082..c3cd89b12e89 100644
--- a/doc/hooks/meson.section.md
+++ b/doc/hooks/meson.section.md
@@ -18,6 +18,16 @@ setup hook registering ninja-based build and install phases.
 
 Controls the flags passed to `meson setup` during configure phase.
 
+#### `mesonBuildDir` {#meson-build-dir}
+
+Directory where Meson will put intermediate files.
+
+Setting this can be useful for debugging multiple Meson builds while in the same source directory, for example, when building for different platforms.
+Different values for each build will prevent build artefacts from interefering with each other.
+This setting has no tangible effect when running the build in a sandboxed derivation.
+
+The default value is `build`.
+
 #### `mesonWrapMode` {#meson-wrap-mode}
 
 Which value is passed as
diff --git a/pkgs/by-name/me/meson/setup-hook.sh b/pkgs/by-name/me/meson/setup-hook.sh
index 55ea8b5c1d97..a88a276f09a8 100644
--- a/pkgs/by-name/me/meson/setup-hook.sh
+++ b/pkgs/by-name/me/meson/setup-hook.sh
@@ -3,6 +3,8 @@
 mesonConfigurePhase() {
     runHook preConfigure
 
+    : ${mesonBuildDir:=build}
+
     local flagsArray=()
 
     if [ -z "${dontAddPrefix-}" ]; then
@@ -28,8 +30,8 @@ mesonConfigurePhase() {
 
     echoCmd 'mesonConfigurePhase flags' "${flagsArray[@]}"
 
-    meson setup build "${flagsArray[@]}"
-    cd build || { echoCmd 'mesonConfigurePhase' "could not cd to build"; exit 1; }
+    meson setup "$mesonBuildDir" "${flagsArray[@]}"
+    cd "$mesonBuildDir" || { echoCmd 'mesonConfigurePhase' "could not cd to $mesonBuildDir"; exit 1; }
 
     if ! [[ -v enableParallelBuilding ]]; then
         enableParallelBuilding=1