CMake: Install prl files from all repo build dirs in a top-level build

Previously, in a top-level build we always generated the final prl
file somewhere under QT_BUILD_DIR (which is qtbase_build_dir). After
each repo was processed by QtPostProcess.cmake, we installed the prl
files found in PROJECT_BINARY_DIR.

For qtquickcontrols2 this meant that qml plugin prl files were placed
under qtbase/qml, but we tried installing the prl files from
qtquickcontrols2/qml, which didn't have any prl files.

In a static Qt build, qmake's qt.prf calls qmlimportscanner to
identify which plugins should be linked to the executable. This worked
fine because the plugin .pri files were installed correctly.

None of the qml plugin library dependencies were linked in though.
This is supposed to happen in qmake's C++ code where it tries to
find the associated prl file of a linked library in order to extract
all its dependencies. Because no prl file was found, linking failed
with multiple undefined symbols.

Fix this by installing the prl files from QT_BUILD_DIR rather than
PROJECT_BINARY_DIR.

Note that this will create multiple install rules for certain files,
but it's harmless. An example is imageformats.

We process qtbase plugins, see qjpeg, issue an install rule from under
the qtbase/plugins/imageformats folder. We then process
qtimageformats plugins, see webp, issue another install rule from
under qtbase/plugins/imageformats.
The first install rule will install both qjpeg and qwebp, the second
install rule will merely say all plugins are up-to-date.

Change-Id: I8a4bb67bfafc1d016eab62f4fe66b6ba378ceeb2
Fixes: QTBUG-93021
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>
(cherry picked from commit 31ee3c84a78afa67eeb4e4b6da5a8181ea62c387)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

1 files changed, 7 insertions, 2 deletions

diff --git a/cmake/QtPostProcessHelpers.cmake b/cmake/QtPostProcessHelpers.cmake
index de4d7deeed..1a0dc02213 100644
--- a/cmake/QtPostProcessHelpers.cmake
+++ b/cmake/QtPostProcessHelpers.cmake
@@ -704,10 +704,15 @@ function(qt_internal_create_config_file_for_standalone_tests)
 endfunction()
 
 function(qt_internal_install_prl_files)
-    # Install prl files
+    # Get locations relative to QT_BUILD_DIR from which prl files should be installed.
     get_property(prl_install_dirs GLOBAL PROPERTY QT_PRL_INSTALL_DIRS)
+
+    # Clear the list of install dirs so the previous values don't pollute the list of install dirs
+    # for the next repository in a top-level build.
+    set_property(GLOBAL PROPERTY QT_PRL_INSTALL_DIRS "")
+
     foreach(prl_install_dir ${prl_install_dirs})
-        qt_install(DIRECTORY "${PROJECT_BINARY_DIR}/${prl_install_dir}/"
+        qt_install(DIRECTORY "${QT_BUILD_DIR}/${prl_install_dir}/"
             DESTINATION ${prl_install_dir}
             FILES_MATCHING PATTERN "*.prl"
         )