qt6.{qtdoc,qttools}: pin LLVM 20, misc cleanups (#444219)

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

@@ -16,12 +16,7 @@ qtModule {
   '';
   nativeBuildInputs = [ (qttools.override { withClang = true; }) ];
   propagatedBuildInputs = [ qtdeclarative ];
-  cmakeFlags = [
-    "-DCMAKE_MESSAGE_LOG_LEVEL=STATUS"
-  ];
-  dontUseNinjaBuild = true;
-  buildFlags = [ "docs" ];
-  dontUseNinjaInstall = true;
-  installFlags = [ "install_docs" ];
-  outputs = [ "out" ];
+
+  ninjaFlags = [ "docs" ];
+  installTargets = [ "install_docs" ];
 }

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

@@ -6,32 +6,18 @@
   qtbase,
   qtdeclarative,
   cups,
-  llvmPackages,
+  llvmPackages_20,
   # clang-based c++ parser for qdoc and lupdate
   withClang ? false,
 }:
 
 qtModule {
   pname = "qttools";
-  buildInputs = lib.optionals withClang [
-    llvmPackages.libclang
-    llvmPackages.llvm
-  ];
-  propagatedBuildInputs = [
-    qtbase
-    qtdeclarative
-  ]
-  ++ lib.optionals stdenv.hostPlatform.isDarwin [ cups ];
-  cmakeFlags = lib.optionals (!stdenv.buildPlatform.canExecute stdenv.hostPlatform) [
-    "-DQt6LinguistTools_DIR=${pkgsBuildBuild.qt6.qttools}/lib/cmake/Qt6LinguistTools"
-    "-DQt6ToolsTools_DIR=${pkgsBuildBuild.qt6.qttools}/lib/cmake/Qt6ToolsTools"
-  ];
+
   patches = [
     ./paths.patch
   ];
-  env.NIX_CFLAGS_COMPILE = toString [
-    "-DNIX_OUTPUT_OUT=\"${placeholder "out"}\""
-  ];
+
   postPatch = ''
     substituteInPlace \
       src/qdoc/catch/CMakeLists.txt \
@@ -39,6 +25,32 @@ qtModule {
       src/qdoc/catch_conversions/CMakeLists.txt \
       --replace ''\'''${CMAKE_INSTALL_INCLUDEDIR}' "$out/include"
   '';
+
+  env.NIX_CFLAGS_COMPILE = toString [
+    "-DNIX_OUTPUT_OUT=\"${placeholder "out"}\""
+  ];
+
+  # FIXME: update to LLVM 21 with Qt 6.10
+  buildInputs = lib.optionals withClang [
+    llvmPackages_20.libclang
+    llvmPackages_20.llvm
+  ];
+
+  propagatedBuildInputs = [
+    qtbase
+    qtdeclarative
+  ]
+  ++ lib.optionals stdenv.hostPlatform.isDarwin [ cups ];
+
+  cmakeFlags =
+    lib.optionals (!stdenv.buildPlatform.canExecute stdenv.hostPlatform) [
+      "-DQt6LinguistTools_DIR=${pkgsBuildBuild.qt6.qttools}/lib/cmake/Qt6LinguistTools"
+      "-DQt6ToolsTools_DIR=${pkgsBuildBuild.qt6.qttools}/lib/cmake/Qt6ToolsTools"
+    ]
+    ++ lib.optionals withClang [
+      "-DFEATURE_clang=ON"
+    ];
+
   postInstall = ''
     mkdir -p "$dev"
     ln -s "$out/bin" "$dev/bin"