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  1. Qt
  2. QTBUG-95713 Post-Qt-6.2.0 release CMake API follow ups
  3. QTBUG-95149

Fix use case of linking an executable to a shared library QML module backing target

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      Context
      https://git.qt.io/alcroito/qt6-cmake-api-review/-/commit/14b4999bc857f5402a3577fe334ebfb3602ad0c2#f3ff9c1b48af14adf093e2af0c5cf2849829bb6d_176_236

      Currently if a user executable directly links to a shared library QML backing target and doesn't deploy the associated shared qml plugin, if the executable has no references to symbols in the shared library, the linker might decide not to add a dependency on the shared library at all. As a result the qml module will not be found at run time.

      The current work around for that is to ensure deployment of the plugins and qmldir files, so that the qml engine can load those.

      We could try to fix this issue by creating an object library with a global constructor that references the qml type registration function of the backing library.

      This object library would then have to be linked to the executable along with the shared backing library. This would ensure the backing library is not discarded by the linker. This would require CMake 3.21 though, for proper object library propagation.

      In some ways this is similar to the Q_IMPORT_PLUGIN object library approach we use for static Qt builds.

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          is duplicated by

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-100655 QML module created with the new QML CMake API does not get automatically loaded on Windows when main.qml locates in the created module

          • P2: Important - Urgent, should be fixed, but will not stop the release.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-122716 Inconsistent static linking of CMake-defined QML modules

          • P2: Important - Urgent, should be fixed, but will not stop the release.
          • Closed
          relates to

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-97816 Prevent linker from discarding unused shared libraries

          • P3: Somewhat important - Should be fixed, but doesn't affect the release in any way.
          • Reported

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-128568 [REG Qt 6.7.0-> 6.8.0 beta4] QML module linked as library doesn't work anymore

          • P1: Critical - Urgent and Important, will STOP the release if matched with set FixVersion field. This includes regressions from the last version that are not edge cases; Data loss; Build issues; All but the most unlikely crashes/lockups/hanging; Serious usability issues and embarrassing bugs & Bugs critical to a deliverable. This is the highest possible priority for requirements.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-123333 qt_add_qml_module with NO_PLUGIN can fail to load when using as-needed linking

          • P2: Important - Urgent, should be fixed, but will not stop the release.
          • Reported
          For Gerrit Dashboard: QTBUG-95149
          # Subject Branch Project Status CR V
          367149,6 WIP: use object lib as interface dependency dev qt/qtdeclarative Status: NEW -2 0

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              fabiankosmale Fabian Kosmale
              alexandru.croitor Alexandru Croitor
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                Updated:

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