Fix QSsl classes to be picked up on Linux

The compile tests that checked for QSsl classes silently failed
because of two different reasons:
1) If Qt was compiled with -fPIC, but the tests weren't, we hit
a compilation error. Solution is to compile with -fPIC if necessary.
2) For some reason when linking, the linker can't find the qt
version tag symbol. Solution is to simply not use the version tag.

Task-number: PYSIDE-599
Change-Id: If8a6ea38b45091bcaced6179a71195d25589ef18
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>

1 files changed, 9 insertions, 0 deletions

diff --git a/sources/pyside2/cmake/Macros/PySideModules.cmake b/sources/pyside2/cmake/Macros/PySideModules.cmake
index 77653925e..0bef89b0c 100644
--- a/sources/pyside2/cmake/Macros/PySideModules.cmake
+++ b/sources/pyside2/cmake/Macros/PySideModules.cmake
@@ -155,10 +155,19 @@ macro(check_qt_class module class optional_source_files dropped_entries)
              "${NAMESPACE_USE}\n"
              "int main() { sizeof(${class}); }\n"
         )
+
+        # Because Qt is built with -fPIC (by default), the compile tests also have to have that.
+        get_property(ADDITIONAL_FLAGS TARGET Qt5::Core PROPERTY INTERFACE_COMPILE_OPTIONS)
+
+        # Don't add version tagging, because for some reason linker fails with:
+        # (.qtversion[qt_version_tag]+0x0): undefined reference to `qt_version_tag'
+        set(ADDITIONAL_FLAGS "${ADDITIONAL_FLAGS} -DQT_NO_VERSION_TAGGING")
+
         try_compile(Q_WORKS ${CMAKE_BINARY_DIR}
                     ${SRC_FILE}
                     CMAKE_FLAGS
                         "-DINCLUDE_DIRECTORIES=${QT_INCLUDE_DIR};${Qt5${_module_no_qt_prefix}_INCLUDE_DIRS}"
+                        "-DCOMPILE_DEFINITIONS:STRING=${ADDITIONAL_FLAGS}"
                     OUTPUT_VARIABLE OUTPUT)
         file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeCheckQtClassTest.log ${OUTPUT})