qt6: add ability to crossbuild (#26529)

recipes/qt/6.x.x/conanfile.py

@@ -264,9 +264,6 @@ def configure(self):
             self.output.debug(f"qt6 option: {option}")
 
     def validate_build(self):
-        if cross_building(self):
-            raise ConanInvalidConfiguration("cross compiling qt 6 is not yet supported. Contributions are welcome")
-
         check_min_cppstd(self, 17)
 
     def validate(self):
@@ -624,7 +621,12 @@ def generate(self):
         if self.options.cross_compile:
             tc.variables["QT_QMAKE_DEVICE_OPTIONS"] = f"CROSS_COMPILE={self.options.cross_compile}"
         if cross_building(self):
-            tc.variables["QT_HOST_PATH"] = self.dependencies.direct_build["qt"].package_folder
+            # Mainly to locate Qt6HostInfoConfig.cmake
+            tc.cache_variables["QT_HOST_PATH"] = self.dependencies.direct_build["qt"].package_folder
+            # Stand-in for Qt6CoreTools - which is loaded for the executable targets
+            tc.cache_variables["CMAKE_PROJECT_Qt_INCLUDE"] = os.path.join(self.dependencies.direct_build["qt"].package_folder, self._cmake_executables_file)
+            # Ensure tools for host are always built
+            tc.cache_variables["QT_FORCE_BUILD_TOOLS"] = True
 
         tc.variables["FEATURE_pkg_config"] = "ON"
         if self.settings.compiler == "gcc" and self.settings.build_type == "Debug" and not self.options.shared:
@@ -663,8 +665,6 @@ def package_id(self):
                     self.info.settings.compiler.runtime = "MT/MTd"
             elif self.info.settings.compiler == "msvc":
                 self.info.settings.compiler.runtime_type = "Release/Debug"
-        if self.info.settings.os == "Android":
-            del self.info.options.android_sdk
 
     def source(self):
         destination = self.source_folder
@@ -835,7 +835,7 @@ def package(self):
                 rmdir(self, os.path.join(self.package_folder, "licenses", module))
         rmdir(self, os.path.join(self.package_folder, "lib", "pkgconfig"))
         for mask in ["Find*.cmake", "*Config.cmake", "*-config.cmake"]:
-            rm(self, mask, self.package_folder, recursive=True)
+            rm(self, mask, self.package_folder, recursive=True, excludes="Qt6HostInfoConfig.cmake")
         rm(self, "*.la*", os.path.join(self.package_folder, "lib"), recursive=True)
         rm(self, "*.pdb*", self.package_folder, recursive=True)
         rm(self, "ensure_pro_file.cmake", self.package_folder, recursive=True)
@@ -850,7 +850,8 @@ def package(self):
                 if os.path.isfile(os.path.join(self.package_folder, "lib", "cmake", m, f"{m[:-5]}Macros.cmake")):
                     continue
 
-            rmdir(self, os.path.join(self.package_folder, "lib", "cmake", m))
+            if m != "Qt6HostInfo":
+                rmdir(self, os.path.join(self.package_folder, "lib", "cmake", m))
 
         extension = ""
         if self.settings.os == "Windows":
@@ -862,7 +863,7 @@ def package(self):
         filecontents += f"set(QT_VERSION_PATCH {ver.patch})\n"
         if self.settings.os == "Macos":
             filecontents += 'set(__qt_internal_cmake_apple_support_files_path "${CMAKE_CURRENT_LIST_DIR}/../../../lib/cmake/Qt6/macos")\n'
-        targets = ["moc", "rcc", "tracegen", "cmake_automoc_parser", "qlalr", "qmake"]
+        targets = ["moc", "qlalr", "rcc", "tracegen", "cmake_automoc_parser", "qmake", "qtpaths", "syncqt", "tracepointgen"]
         if self.options.with_dbus:
             targets.extend(["qdbuscpp2xml", "qdbusxml2cpp"])
         if self.options.gui:

recipes/qt/6.x.x/test_package/conanfile.py

@@ -2,14 +2,14 @@
 
 from conan import ConanFile
 from conan.tools.build import can_run
-from conan.tools.cmake import CMake, cmake_layout
+from conan.tools.cmake import CMake, CMakeToolchain, cmake_layout
 from conan.tools.env import VirtualRunEnv
 from conan.tools.files import copy, save
 
 
 class TestPackageConan(ConanFile):
     settings = "os", "arch", "compiler", "build_type"
-    generators = "CMakeDeps", "CMakeToolchain", "VirtualBuildEnv"
+    generators = "CMakeDeps", "VirtualBuildEnv"
     test_type = "explicit"
 
     def layout(self):
@@ -21,12 +21,20 @@ def requirements(self):
     def build_requirements(self):
         if not can_run(self):
             self.tool_requires(self.tested_reference_str)
+            self.tool_requires("cmake/[>=3.27 <4]")
 
     def generate(self):
         path = self.dependencies["qt"].package_folder.replace("\\", "/")
         save(self, "qt.conf", f"""[Paths]
 Prefix = {path}""")
 
+        tc = CMakeToolchain(self)
+        if 'qt' in self.dependencies.build:
+            qt_tools_rootdir = self.conf.get("user.qt:tools_directory", None)
+            for tool in ["moc", "rcc", "uic"]:
+                tc.cache_variables[f"CMAKE_AUTO{tool.upper()}_EXECUTABLE"] = os.path.join(qt_tools_rootdir, f"{tool}.exe" if self.settings_build.os == "Windows" else tool)
+        tc.generate()
+
         VirtualRunEnv(self).generate()
         if can_run(self):
             VirtualRunEnv(self).generate(scope="build")