From 40d415f4df5548679dcb47331c83a2d4e7741ae8 Mon Sep 17 00:00:00 2001
From: Randy Eckenrode <randy@largeandhighquality.com>
Date: Sun, 22 Sep 2024 23:20:16 -0400
Subject: [PATCH] darwin: add darwinMinVersionHook

Adding the hook allows the deployment target to be changed without
having to mess with the stdenv. The can also be propagated, which is
useful for libraries that have a minimum deployment target higher than
the default in nixpkgs. In that case, they can propagate the hook to
ensure library users are not targeting an unsupported version.
---
 .../darwin-min-version-hook/setup-hook.sh     | 26 +++++++++++++++++++
 pkgs/top-level/all-packages.nix               | 12 +++++++++
 2 files changed, 38 insertions(+)
 create mode 100644 pkgs/os-specific/darwin/darwin-min-version-hook/setup-hook.sh

diff --git a/pkgs/os-specific/darwin/darwin-min-version-hook/setup-hook.sh b/pkgs/os-specific/darwin/darwin-min-version-hook/setup-hook.sh
new file mode 100644
index 000000000000..17a42eb02ef4
--- /dev/null
+++ b/pkgs/os-specific/darwin/darwin-min-version-hook/setup-hook.sh
@@ -0,0 +1,26 @@
+local role_post
+getHostRole
+
+# Compare the requested deployment target to the existing one. The deployment target has to be a version number,
+# and this hook tries to do the right thing with deployment targets set outside of it, so it has to parse
+# the version numbers for the comparison manually.
+
+local darwinMinVersion=@deploymentTarget@
+local darwinMinVersionVar=@darwinMinVersionVariable@${role_post}
+
+local currentDeploymentTargetArr
+IFS=. read -a currentDeploymentTargetArr <<< "${!darwinMinVersionVar-0.0.0}"
+
+local darwinMinVersionArr
+IFS=. read -a darwinMinVersionArr <<< "$darwinMinVersion"
+
+local currentDeploymentTarget
+currentDeploymentTarget=$(printf "%02d%02d%02d" "${currentDeploymentTargetArr[0]-0}" "${currentDeploymentTargetArr[1]-0}" "${currentDeploymentTargetArr[2]-0}")
+
+darwinMinVersion=$(printf "%02d%02d%02d" "${darwinMinVersionArr[0]-0}" "${darwinMinVersionArr[1]-0}" "${darwinMinVersionArr[2]-0}")
+
+if [ "$darwinMinVersion" -gt "$currentDeploymentTarget" ]; then
+    export "$darwinMinVersionVar"=@deploymentTarget@
+fi
+
+unset -v role_post currentDeploymentTarget currentDeploymentTargetArr darwinMinVersion darwinMinVersionArr darwinMinVersionVar
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index b6744b93ea24..fd4ca3df70c7 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -23740,6 +23740,18 @@ with pkgs;
 
   plumed = callPackage ../development/libraries/science/chemistry/plumed { };
 
+  ### DEVELOPMENT / LIBRARIES / DARWIN SDKS
+
+  darwinMinVersionHook =
+    deploymentTarget:
+    makeSetupHook {
+      name = "darwin-deployment-target-hook-${deploymentTarget}";
+      substitutions = {
+        darwinMinVersionVariable = lib.escapeShellArg stdenv.hostPlatform.darwinMinVersionVariable;
+        deploymentTarget = lib.escapeShellArg deploymentTarget;
+      };
+    } ../os-specific/darwin/darwin-min-version-hook/setup-hook.sh;
+
   ### DEVELOPMENT / LIBRARIES / AGDA
 
   agdaPackages = callPackage ./agda-packages.nix {