CMake: Add doc_tools build and install targets

Add doc_tools and install_doc_tools custom targets.
These are meant to build and install documentation and code generation
tools that participate in documentation generation.

Such tools should be annotated with the IS_DOC_TOOL option to their
qt_internal_add_tool call.

In qtbase, such generator tools are qdbusxml2cpp and qvkgen.

Task-number: QTBUG-91243
Task-number: QTBUG-128730
Change-Id: Idebffc6f50d8547ce76c1102a20d60d436e44cfd
Reviewed-by: Alexey Edelev <alexey.edelev@qt.io>
(cherry picked from commit 3066e9e38deada5f99a47449e4ef84eebc5219f5)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

cmake/QtBuildRepoHelpers.cmake

@@ -308,6 +308,7 @@ macro(qt_build_repo_begin)
     if(NOT TARGET host_tools)
         add_custom_target(host_tools)
         add_custom_target(bootstrap_tools)
+        add_custom_target(doc_tools)
 
         # TODO: Investigate complexity of installing tools for shared builds.
         # Currently installing host tools without libraries only really makes sense for static
@@ -321,9 +322,21 @@ macro(qt_build_repo_begin)
                 COMMAND ${CMAKE_COMMAND}
                     --install ${CMAKE_BINARY_DIR} --component host_tools --strip
             )
+
+            add_custom_target(install_doc_tools
+                COMMAND ${CMAKE_COMMAND}
+                    --install ${CMAKE_BINARY_DIR} --component doc_tools
+            )
+            add_custom_target(install_doc_tools_stripped
+                COMMAND ${CMAKE_COMMAND}
+                    --install ${CMAKE_BINARY_DIR} --component doc_tools --strip
+            )
+
             if(NOT QT_INTERNAL_NO_INSTALL_TOOLS_BUILD_DEPS)
                 add_dependencies(install_tools host_tools)
                 add_dependencies(install_tools_stripped host_tools)
+                add_dependencies(install_doc_tools doc_tools)
+                add_dependencies(install_doc_tools_stripped doc_tools)
             endif()
         endif()
     endif()

cmake/QtToolHelpers.cmake

@@ -22,6 +22,10 @@
 #     TRY_RUN_FLAGS
 #         Command line flags that are going to be passed to the tool for testing its correctness.
 #         If no flags were given, we default to `-v`.
+#     REQUIRED_FOR_DOCS
+#         Specifies that the built tool is required to generate documentation. Examples are qdoc,
+#         and qvkgen (because they participate in header file generation, which are needed for
+#         documentation generation).
 #
 # One-value Arguments:
 #     EXTRA_CMAKE_FILES
@@ -51,6 +55,7 @@ function(qt_internal_add_tool target_name)
         EXCEPTIONS
         NO_UNITY_BUILD
         TRY_RUN
+        REQUIRED_FOR_DOCS
         ${__qt_internal_sbom_optional_args}
     )
     set(one_value_keywords
@@ -170,6 +175,9 @@ function(qt_internal_add_tool target_name)
 
     if(TARGET host_tools)
         add_dependencies(host_tools "${target_name}")
+        if(arg_REQUIRED_FOR_DOCS)
+            add_dependencies(doc_tools "${target_name}")
+        endif()
         if(arg_CORE_LIBRARY STREQUAL "Bootstrap")
             add_dependencies(bootstrap_tools "${target_name}")
         endif()

src/tools/qdbusxml2cpp/CMakeLists.txt

@@ -7,6 +7,7 @@
 
 qt_get_tool_target_name(target_name qdbusxml2cpp)
 qt_internal_add_tool(${target_name}
+    REQUIRED_FOR_DOCS
     TRY_RUN
     TARGET_DESCRIPTION "Qt D-Bus XML to C++ Compiler"
     TOOLS_TARGET DBus

src/tools/qvkgen/CMakeLists.txt

@@ -7,6 +7,7 @@
 
 qt_get_tool_target_name(target_name qvkgen)
 qt_internal_add_tool(${target_name}
+    REQUIRED_FOR_DOCS
     TARGET_DESCRIPTION "Qt Vulkan Header Generator"
     INSTALL_DIR "${INSTALL_LIBEXECDIR}"
     TOOLS_TARGET Gui