qt6.qtbase: build with apple-sdk_15, propagate apple-sdk_12

As of Qt 6.8, the macOS 15 SDK is supported for building, and support
for targeting macOS 11 has been dropped. (Another good reason for
supporting only 3 to 4 macOS releases.)

Previously the build and target SDKs were swapped, probably because the
dependency lists are in a confusing order. Move them into a central
place to reduce duplication and keep macOS platform support in one
prominent location.

Fixes: 830b9fe572

pkgs/development/libraries/qt-6/default.nix

@@ -10,7 +10,9 @@
 , gst_all_1
 , libglvnd
 , darwin
-, overrideSDK
+, apple-sdk_15
+, apple-sdk_12
+, darwinMinVersionHook
 , buildPackages
 , python3
 , config
@@ -28,15 +30,27 @@ let
         inherit (self) qtModule;
         inherit srcs python3 stdenv;
       });
+
+      # Per <https://doc.qt.io/qt-6/macos.html#supported-versions>.
+      # This should reflect the lowest “Target Platform” and the
+      # highest “Build Environment”.
+      apple-sdk_qt = apple-sdk_15;
+      darwinDeploymentTargetDeps = [
+        apple-sdk_12
+        (darwinMinVersionHook "12.0")
+      ];
     in
     {
 
       inherit callPackage srcs;
 
-      qtModule = callPackage ./qtModule.nix { };
+      qtModule = callPackage ./qtModule.nix {
+        inherit apple-sdk_qt;
+      };
 
       qtbase = callPackage ./modules/qtbase.nix {
         withGtk3 = !stdenv.hostPlatform.isMinGW;
+        inherit apple-sdk_qt darwinDeploymentTargetDeps;
         inherit (srcs.qtbase) src version;
         patches = [
           ./patches/0001-qtbase-qmake-always-use-libname-instead-of-absolute-.patch

pkgs/development/libraries/qt-6/modules/qtbase.nix

@@ -67,9 +67,8 @@
 , unixODBCDrivers
   # darwin
 , moveBuildTree
-, apple-sdk_11
-, apple-sdk_14
-, darwinMinVersionHook
+, apple-sdk_qt
+, darwinDeploymentTargetDeps
 , xcbuild
   # mingw
 , pkgsBuildBuild
@@ -156,10 +155,8 @@ stdenv.mkDerivation rec {
     xorg.libXtst
     xorg.xcbutilcursor
     libepoxy
-  ] ++ lib.optionals stdenv.hostPlatform.isDarwin [
-    apple-sdk_14
-    (darwinMinVersionHook "11.0")
-  ] ++ lib.optionals libGLSupported [
+  ] ++ lib.optionals stdenv.hostPlatform.isDarwin darwinDeploymentTargetDeps
+  ++ lib.optionals libGLSupported [
     libGL
   ] ++ lib.optionals stdenv.hostPlatform.isMinGW [
     vulkan-headers
@@ -171,8 +168,7 @@ stdenv.mkDerivation rec {
   ] ++ lib.optionals (lib.meta.availableOn stdenv.hostPlatform libinput) [
     libinput
   ] ++ lib.optionals stdenv.hostPlatform.isDarwin [
-    apple-sdk_11
-    (darwinMinVersionHook "11.0")
+    apple-sdk_qt
   ]
   ++ lib.optional withGtk3 gtk3
   ++ lib.optional (libmysqlclient != null && !stdenv.hostPlatform.isMinGW) libmysqlclient

pkgs/development/libraries/qt-6/qtModule.nix

@@ -1,6 +1,6 @@
 { lib
 , stdenv
-, apple-sdk_14
+, apple-sdk_qt
 , cmake
 , ninja
 , perl
@@ -22,8 +22,7 @@ stdenv.mkDerivation (args // {
 
   buildInputs =
     args.buildInputs or [ ]
-    # Per https://doc.qt.io/qt-6/macos.html#supported-versions
-    ++ lib.optionals stdenv.isDarwin [ apple-sdk_14 ];
+    ++ lib.optionals stdenv.hostPlatform.isDarwin [ apple-sdk_qt ];
   nativeBuildInputs = (args.nativeBuildInputs or [ ]) ++ [ cmake ninja perl ]
     ++ lib.optionals stdenv.hostPlatform.isDarwin [ moveBuildTree ];
   propagatedBuildInputs =