qt5: cross compile with a clean separation of build and host binaries

pkgs/development/libraries/qt-5/5.15/default.nix

@@ -10,25 +10,15 @@
   generateSplicesForMkScope,
   lib,
   stdenv,
-  gcc14Stdenv,
   fetchurl,
   fetchgit,
   fetchpatch,
   fetchFromGitHub,
   makeSetupHook,
-  makeWrapper,
-  bison,
-  cups ? null,
-  harfbuzz,
-  libGL,
-  perl,
   python3,
-  gstreamer,
-  gst-plugins-base,
-  gtk3,
-  dconf,
   llvmPackages_19,
   darwin,
+  buildPackages,
 
   # options
   developerBuild ? false,
@@ -59,13 +49,20 @@ let
         url = "https://gitlab.alpinelinux.org/alpine/aports/-/raw/81b14ae4eed038662b53cd20786fd5e0816279ec/community/qt5-qtbase/loongarch64.patch";
         hash = "sha256-BnpejF6/L73kVVts0R0/OMbVN8G4DXVFwBMJPLU9QbE=";
       })
+      (fetchpatch {
+        url = "https://salsa.debian.org/qt-kde-team/qt/qtbase/-/raw/6910758e1141f8ea65a8f2359ac30163d65bf6e2/debian/patches/cross_build_mysql.diff";
+        hash = "sha256-tzmmLmMXmeDwRVjdpWekDJvSkrIIlslC12HP7XPcm3E=";
+      })
+      ./qtbase.patch.d/0015-qtbase-cross-build.patch
     ];
     qtdeclarative = [
       ./qtdeclarative.patch
       # prevent headaches from stale qmlcache data
       ./qtdeclarative-default-disable-qmlcache.patch
       # add version specific QML import path
       ./qtdeclarative-qml-paths.patch
+      ./qtdeclarative-gcc15.patch
+      ./qtdeclarative-cross-build.patch
     ];
     qtlocation = lib.optionals stdenv.cc.isClang [
       # Fix build with Clang 16
@@ -201,6 +198,7 @@ let
       # See: https://bugreports.qt.io/browse/QTBUG-124375
       # Backport of: https://code.qt.io/cgit/qt/qtwebengine-chromium.git/commit/?id=a766045f65f934df3b5f1aa63bc86fbb3e003a09
       ./qtwebengine-ninja-1.12.patch
+      ./qtwebengine-cross-build.patch
     ]
     ++ lib.optionals stdenv.hostPlatform.isDarwin [
       ./qtwebengine-darwin-no-platform-check.patch
@@ -236,35 +234,48 @@ let
       ./qtwebkit.patch
       ./qtwebkit-icu68.patch
       ./qtwebkit-cstdint.patch
+      (fetchpatch {
+        url = "https://src.fedoraproject.org/rpms/qt5-qtwebkit/raw/84f3c61c46bce99bfbd70d8c202e022d62f2ea9a/f/qtwebkit-icu76.patch";
+        sha256 = "sha256-Z+ot7R5Dy+F08FbcXzN4MB2ttxLg0I0P8uVErpbFiu4=";
+      })
+      (fetchpatch {
+        url = "https://src.fedoraproject.org/rpms/qt5-qtwebkit/raw/84f3c61c46bce99bfbd70d8c202e022d62f2ea9a/f/webkit-offlineasm-warnings-ruby27.patch";
+        sha256 = "sha256-g+qkAJD78lPdZzZZ910SZqk0yJlJIBZh9ue4ClRD5L4=";
+      })
+      (fetchpatch {
+        url = "https://src.fedoraproject.org/rpms/qt5-qtwebkit/raw/84f3c61c46bce99bfbd70d8c202e022d62f2ea9a/f/qtwebkit-fix-build-gcc14.patch";
+        sha256 = "sha256-K7TgGux34dMN0Mnm4EsJhNKLdy1VdKTAE3HGRD8KARU=";
+      })
     ]
     ++ lib.optionals stdenv.hostPlatform.isDarwin [
       ./qtwebkit-darwin-no-readline.patch
       ./qtwebkit-darwin-no-qos-classes.patch
     ];
-    qttools = [ ./qttools.patch ];
+    qttools = [
+      ./qttools.patch
+      ./qttools-cross-build.patch
+    ];
   };
 
   addPackages =
     self:
     let
-      qtModuleWithStdenv =
-        stdenv:
-        callPackage ../qtModule.nix {
-          inherit patches;
-          # Use a variant of mkDerivation that does not include wrapQtApplications
-          # to avoid cyclic dependencies between Qt modules.
-          mkDerivation = (callPackage ../mkDerivation.nix { wrapQtAppsHook = null; }) stdenv.mkDerivation;
-        };
-      qtModule = qtModuleWithStdenv stdenv;
+      qtModule = callPackage ../qtModule.nix {
+        inherit patches;
+        # Use a variant of mkDerivation that does not include wrapQtApplications
+        # to avoid cyclic dependencies between Qt modules.
+        mkDerivation = (callPackage ../mkDerivation.nix { wrapQtAppsHook = null; }) stdenv.mkDerivation;
+      };
 
-      callPackage = self.newScope {
-        inherit
-          qtCompatVersion
-          qtModule
-          srcs
-          stdenv
-          ;
+      qtbase-bootstrap = buildPackages.qt5.qtbase.override { bootstrapBuild = true; };
+      # qtbase won't be spliced here, but that's fine as it's only a buildInput
+      qttools-bootstrap = buildPackages.qt5.qttools.override {
+        qtbase = qtbase-bootstrap;
+        qtdeclarative = null;
       };
+
+      #                              ↓Things available only to packages in the scope↓
+      callPackage = self.newScope { inherit qtbase-bootstrap qttools-bootstrap stdenv; };
     in
     {
 
@@ -282,14 +293,7 @@ let
       qtbase = callPackage ../modules/qtbase.nix {
         inherit (srcs.qtbase) src version;
         patches = patches.qtbase;
-        inherit
-          bison
-          cups
-          harfbuzz
-          libGL
-          ;
         withGtk3 = !stdenv.hostPlatform.isDarwin;
-        inherit dconf gtk3;
         inherit developerBuild decryptSslTraffic;
       };
 
@@ -305,9 +309,7 @@ let
       qtlocation = callPackage ../modules/qtlocation.nix { };
       qtlottie = callPackage ../modules/qtlottie.nix { };
       qtmacextras = callPackage ../modules/qtmacextras.nix { };
-      qtmultimedia = callPackage ../modules/qtmultimedia.nix {
-        inherit gstreamer gst-plugins-base;
-      };
+      qtmultimedia = callPackage ../modules/qtmultimedia.nix { };
       qtnetworkauth = callPackage ../modules/qtnetworkauth.nix { };
       qtpim = callPackage ../modules/qtpim.nix { };
       qtpositioning = callPackage ../modules/qtpositioning.nix { };
@@ -330,22 +332,13 @@ let
       qtvirtualkeyboard = callPackage ../modules/qtvirtualkeyboard.nix { };
       qtwayland = callPackage ../modules/qtwayland.nix { };
       qtwebchannel = callPackage ../modules/qtwebchannel.nix { };
-      qtwebengine =
-        # Actually propagating stdenv change
-        let
-          # Won’t build with Clang 20, as `-Wenum-constexpr-conversion`
-          # was made a hard error.
-          # qt5webengine no longer maintained, FTBFS with GCC 15
-          stdenv' = if stdenv.cc.isClang then llvmPackages_19.stdenv else gcc14Stdenv;
-          qtModule' = qtModuleWithStdenv stdenv';
-        in
-        callPackage ../modules/qtwebengine.nix {
-          inherit (srcs.qtwebengine) version;
-          inherit (darwin) bootstrap_cmds;
-          stdenv = stdenv';
-          qtModule = qtModule';
-          python = python3;
-        };
+      qtwebengine = callPackage ../modules/qtwebengine.nix {
+        # Won’t build with Clang 20, as `-Wenum-constexpr-conversion`
+        # was made a hard error.
+        stdenv = if stdenv.cc.isClang then llvmPackages_19.stdenv else stdenv;
+        inherit (srcs.qtwebengine) version;
+        inherit (darwin) bootstrap_cmds;
+      };
       qtwebglplugin = callPackage ../modules/qtwebglplugin.nix { };
       qtwebkit = callPackage ../modules/qtwebkit.nix { };
       qtwebsockets = callPackage ../modules/qtwebsockets.nix { };
@@ -356,16 +349,10 @@ let
       env = callPackage ../qt-env.nix { };
 
       qmake = callPackage (
-        { qtbase }:
+        { qtbase-bootstrap }:
         makeSetupHook {
           name = "qmake-hook";
-          ${
-            if stdenv.buildPlatform == stdenv.hostPlatform then
-              "propagatedBuildInputs"
-            else
-              "depsTargetTargetPropagated"
-          } =
-            [ qtbase.dev ];
+          propagatedBuildInputs = [ qtbase-bootstrap.qmake ];
           substitutions = {
             inherit debug;
             fix_qmake_libtool = ../hooks/fix-qmake-libtool.sh;
@@ -381,9 +368,9 @@ let
         }:
         makeSetupHook {
           name = "wrap-qt5-apps-hook";
-          propagatedBuildInputs = [
+          propagatedBuildInputs = [ makeBinaryWrapper ];
+          depsTargetTargetPropagated = [
             qtbase.dev
-            makeBinaryWrapper
           ]
           ++ lib.optional stdenv.hostPlatform.isLinux qtwayland.dev;
         } ../hooks/wrap-qt-apps-hook.sh
@@ -393,25 +380,10 @@ let
       full = throw "libsForQt5.full has been removed. Please use individual packages instead."; # Added 2025-10-18
     };
 
-  baseScope = makeScopeWithSplicing' {
+  finalScope = makeScopeWithSplicing' {
     otherSplices = generateSplicesForMkScope "qt5";
     f = addPackages;
   };
 
-  bootstrapScope = baseScope.overrideScope (
-    final: prev: {
-      qtbase = prev.qtbase.override { qttranslations = null; };
-      qtdeclarative = null;
-    }
-  );
-
-  finalScope = baseScope.overrideScope (
-    final: prev: {
-      # qttranslations causes eval-time infinite recursion when
-      # cross-compiling; disabled for now.
-      qttranslations =
-        if stdenv.buildPlatform == stdenv.hostPlatform then bootstrapScope.qttranslations else null;
-    }
-  );
 in
 finalScope