Generate information about user-facing applications in build dir

When packaging different Qt versions for Linux distributions (or any
distribution with a common bin dir), Qt tools cannot be installed to
/usr/bin, because the executable names of the different Qt versions
clash.

To solve this conflict, our recommendation is to install Qt's tools to
/usr/lib/qt6/bin and to create versioned symlinks to user-facing tools
in /usr/bin.

User-facing tools are tools that are supposed to be started manually by
the user. They are marked in Qt's build system. Distro package
maintainers can now configure with
  -DCMAKE_INSTALL_PREFIX=/usr
  -DINSTALL_BINDIR=/usr/lib/qt6/bin
  -DINSTALL_PUBLICBINDIR=/usr/bin
and will find a file called user_facing_tool_links.txt in the build
directory after the cmake run. Nothing will be installed to
INSTALL_PUBLICBINDIR.

Each line of user_facing_tool_links.txt consists of the installation
path of a user-facing application followed by a space and the versioned
link name in INSTALL_PUBLICBINDIR.

Example content:
/usr/lib/qt6/bin/qmake /usr/bin/qmake6

To actually create the versioned symlinks, the content of this file can
be fed to ln like this:
  xargs ln -s < build-dir/user_facing_tool_links.txt

Or the package maintainer may decide to do something completely
different as suits their needs.

This patch adds the USER_FACING argument to qt_internal_add_tool to mark
tools as user-facing. In addition, every Qt created by
qt_internal_add_app is treated as user-facing.

The only tool this patch marks as user-facing in qtbase is qmake.

Fixes: QTBUG-89170
Change-Id: I52673b1c8d40f40f56a74203065553115e2c4de5
Reviewed-by: Kai Koehne <[email protected]>
Reviewed-by: Shawn Rutledge <[email protected]>
(cherry picked from commit b1ad7f9)
Reviewed-by: Fabian Kosmale <[email protected]>

cmake/QtAppHelpers.cmake

@@ -49,6 +49,9 @@ function(qt_internal_add_app target)
     # if CONFIG += console was encountered during conversion.
     set_target_properties("${target}" PROPERTIES WIN32_EXECUTABLE TRUE)
 
+    # Consider every app as user facing tool.
+    set_property(GLOBAL APPEND PROPERTY QT_USER_FACING_TOOL_TARGETS ${target})
+
     qt_add_list_file_finalizer(qt_internal_finalize_app ${target})
 endfunction()
 

cmake/QtPostProcess.cmake

@@ -13,3 +13,4 @@ if (ANDROID)
 endif()
 
 qt_internal_install_prl_files()
+qt_internal_generate_user_facing_tools_info()

cmake/QtPostProcessHelpers.cmake

@@ -707,3 +707,24 @@ function(qt_internal_install_prl_files)
         )
     endforeach()
 endfunction()
+
+function(qt_internal_generate_user_facing_tools_info)
+    if("${INSTALL_PUBLICBINDIR}" STREQUAL "")
+        return()
+    endif()
+    get_property(user_facing_tool_targets GLOBAL PROPERTY QT_USER_FACING_TOOL_TARGETS)
+    set(lines "")
+    foreach(target ${user_facing_tool_targets})
+        get_target_property(filename ${target} OUTPUT_NAME)
+        if(NOT filename)
+            set(filename ${target})
+        endif()
+        qt_path_join(tool_target_path "${CMAKE_INSTALL_PREFIX}" "${INSTALL_BINDIR}" "${filename}")
+        qt_path_join(tool_link_path "${INSTALL_PUBLICBINDIR}" "${filename}${PROJECT_VERSION_MAJOR}")
+        list(APPEND lines "${tool_target_path} ${tool_link_path}")
+    endforeach()
+    string(REPLACE ";" "\n" content "${lines}")
+    string(APPEND content "\n")
+    set(out_file "${PROJECT_BINARY_DIR}/user_facing_tool_links.txt")
+    file(WRITE "${out_file}" "${content}")
+endfunction()

cmake/QtToolHelpers.cmake

@@ -2,6 +2,9 @@
 # The BOOTSTRAP option allows building it as standalone program, otherwise
 # it will be linked against QtCore.
 #
+# USER_FACING can be passed to mark the tool as a program that is supposed to be
+# started directly by users.
+#
 # We must pass this function a target name obtained from
 # qt_get_tool_target_name like this:
 #     qt_get_tool_target_name(target_name my_tool)
@@ -22,7 +25,7 @@ function(qt_internal_add_tool target_name)
     qt_tool_target_to_name(name ${target_name})
     set(one_value_keywords TOOLS_TARGET EXTRA_CMAKE_FILES INSTALL_DIR
                            ${__default_target_info_args})
-    qt_parse_all_arguments(arg "qt_add_tool" "BOOTSTRAP;NO_QT;NO_INSTALL"
+    qt_parse_all_arguments(arg "qt_add_tool" "BOOTSTRAP;NO_QT;NO_INSTALL;USER_FACING"
                                "${one_value_keywords}"
                                "${__default_private_args}" ${ARGN})
 
@@ -189,6 +192,10 @@ function(qt_internal_add_tool target_name)
         )
     endif()
 
+    if(arg_USER_FACING)
+        set_property(GLOBAL APPEND PROPERTY QT_USER_FACING_TOOL_TARGETS ${target_name})
+    endif()
+
     # If building with a multi-config configuration, the main configuration tool will be placed in
     # ./bin, while the rest will be in <CONFIG> specific subdirectories.
     qt_get_tool_cmake_configuration(tool_cmake_configuration)

qmake/CMakeLists.txt

@@ -8,7 +8,7 @@ qt_get_tool_target_name(target_name qmake)
 qt_internal_add_tool(${target_name}
     NO_QT # special case
     TOOLS_TARGET Core # special case
-    # GUI # special case: remove this
+    USER_FACING
     SOURCES
         ../src/3rdparty/pcre2/src/config.h
         ../src/3rdparty/pcre2/src/pcre2.h