CMake: Work around AUTOUIC Ninja Multi-Config issue with EP examples

AUTOUIC doesn't handle relative paths to .ui files in parent
directories when using Ninja Multi-Config.

The designer tool in qttools has such a ui file. This leads to the
following error when trying to build qttools together with examples as
ExternalProjects and Ninja Multi-Config:

  ninja: error: 'src/designer/src/designer/designer_autogen/
    include_Debug/ui_preferencesdialog.h', needed by
    'src/designer/src/designer/designer_autogen:Debug',
    missing and no known rule to make it

Until cmake is fixed, we can work around the issue by not adding
designer as a dependency when building EP examples, because no example
tries to use the app.

We can't exclude all apps from example dependencies because some
modules use qt_internal_add_app for tools as well, which are called
from public CMake API and also examples.
An example of this is qtapplicationmanager.

Given that we can't exclude all apps, introduce a function to
allow skipping single targets when building EP examples.

This will allow excluding designer specifically.

The examples will now depend on a new ${repo}_src_for_examples target
rather than ${repo}_src, which will exclude skipped targets.

Task-number: QTBUG-90820
Task-number: QTBUG-96232
Task-number: QTBUG-110369
Change-Id: I2f900253bbf7bac917f2293ef604ab3ea8f298e1
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>

1 files changed, 21 insertions, 1 deletions

diff --git a/cmake/QtBuildInternals/QtBuildInternalsConfig.cmake b/cmake/QtBuildInternals/QtBuildInternalsConfig.cmake
index 9d8df960d2..6214b3c389 100644
--- a/cmake/QtBuildInternals/QtBuildInternalsConfig.cmake
+++ b/cmake/QtBuildInternals/QtBuildInternalsConfig.cmake
@@ -287,7 +287,27 @@ function(qt_build_internals_add_toplevel_targets)
                 COMMENT "Building everything in ${qt_repo_targets_name}/${qt_repo_target_basename}")
             add_dependencies("${qt_repo_target_name}" ${qt_repo_targets})
             list(APPEND qt_repo_target_all "${qt_repo_target_name}")
+
+            # Create special dependency target for External Project examples excluding targets
+            # marked as skipped.
+            set(qt_repo_target_name
+                "${qt_repo_targets_name}_${qt_repo_target_basename}_for_examples")
+            add_custom_target("${qt_repo_target_name}")
+
+            set(unskipped_targets "")
+            foreach(target IN LISTS qt_repo_targets)
+                if(TARGET "${target}")
+                    qt_internal_is_target_skipped_for_examples("${target}" is_skipped)
+                    if(NOT is_skipped)
+                        list(APPEND unskipped_targets "${target}")
+                    endif()
+                endif()
+            endforeach()
+            if(unskipped_targets)
+                add_dependencies("${qt_repo_target_name}" ${unskipped_targets})
+            endif()
         endif()
+
     endforeach()
     if (qt_repo_target_all)
         # Note qt_repo_targets_name is different from qt_repo_target_name that is used above.
@@ -813,7 +833,7 @@ macro(qt_examples_build_begin)
         set(QT_EXAMPLE_DEPENDENCIES qt_plugins ${arg_DEPENDS})
 
         if(TARGET ${qt_repo_targets_name}_src)
-            list(APPEND QT_EXAMPLE_DEPENDENCIES ${qt_repo_targets_name}_src)
+            list(APPEND QT_EXAMPLE_DEPENDENCIES ${qt_repo_targets_name}_src_for_examples)
         endif()
 
         if(TARGET ${qt_repo_targets_name}_tools)