Include QtVersionOption before all Qt5 find_package calls

This doesn't make all these modules actually work with Qt6 yet, but it
prevents them from unconditionally pulling in Qt5 in a Qt6 build.

This is useful in order to even be able to pass a CMake run to the
point one can port, test and debug the rest.

4 files changed, 13 insertions, 8 deletions

diff --git a/modules/ECMAddQch.cmake b/modules/ECMAddQch.cmake
index 8ba91768..f494c543 100644
--- a/modules/ECMAddQch.cmake
+++ b/modules/ECMAddQch.cmake
@@ -257,6 +257,7 @@ Since 5.36.0.
 #]=======================================================================]
 
 include(CMakeParseArguments)
+include(${CMAKE_CURRENT_LIST_DIR}/../modules/QtVersionOption.cmake)
 include(ECMQueryQmake)
 
 
@@ -279,7 +280,7 @@ function(_ecm_ensure_qt_qch_targets)
     # Ideally one day Qt CMake Config files provide these
     if(NOT TARGET Qt5Core_QCH)
         # get Qt version, if any
-        find_package(Qt5Core CONFIG QUIET)
+        find_package(Qt${QT_MAJOR_VERSION}Core CONFIG QUIET)
         # lookup tag files
         query_qmake(qt_docs_dir QT_INSTALL_DOCS TRY)
         find_path(_qtcoreTagsPath qtcore/qtcore.tags
diff --git a/modules/ECMAddQtDesignerPlugin.cmake b/modules/ECMAddQtDesignerPlugin.cmake
index 7d3dfb69..72dc683f 100644
--- a/modules/ECMAddQtDesignerPlugin.cmake
+++ b/modules/ECMAddQtDesignerPlugin.cmake
@@ -179,6 +179,7 @@ Since 5.62.0.
 #]=======================================================================]
 
 include(CMakeParseArguments)
+include(${CMAKE_CURRENT_LIST_DIR}/QtVersionOption.cmake)
 
 # helper method
 # escapes string for C++ code
@@ -442,7 +443,7 @@ macro(ecm_add_qtdesignerplugin target)
     # Check deps
     # peek at Qt5Core to learn about the version to decide whether Qt5UiPlugin is enough
     if(NOT Qt5Core_FOUND)
-        find_package(Qt5Core QUIET CONFIG)
+        find_package(Qt${QT_MAJOR_VERSION}Core QUIET CONFIG)
     endif()
     if(Qt5Core_VERSION VERSION_LESS "5.5.0")
         set(_qtdesigner_tobefound TRUE)
@@ -454,15 +455,15 @@ macro(ecm_add_qtdesignerplugin target)
         set(_qtuiplugin_tobefound TRUE)
     endif()
     if(NOT Qt5Designer_FOUND AND _qtdesigner_tobefound)
-        find_package(Qt5Designer QUIET CONFIG)
-        set_package_properties(Qt5Designer PROPERTIES
+        find_package(Qt${QT_MAJOR_VERSION}Designer QUIET CONFIG)
+        set_package_properties(Qt${QT_MAJOR_VERSION}Designer PROPERTIES
             PURPOSE "Required to build Qt Designer plugins"
             TYPE REQUIRED
         )
     endif()
     if(NOT Qt5UiPlugin_FOUND AND _qtuiplugin_tobefound)
-        find_package(Qt5UiPlugin QUIET CONFIG)
-        set_package_properties(Qt5UiPlugin PROPERTIES
+        find_package(Qt${QT_MAJOR_VERSION}UiPlugin QUIET CONFIG)
+        set_package_properties(Qt${QT_MAJOR_VERSION}UiPlugin PROPERTIES
             PURPOSE "Required to build Qt Designer plugins"
             TYPE REQUIRED
         )
diff --git a/modules/ECMPoQmTools.cmake b/modules/ECMPoQmTools.cmake
index 86480b71..bf9efe0e 100644
--- a/modules/ECMPoQmTools.cmake
+++ b/modules/ECMPoQmTools.cmake
@@ -83,6 +83,8 @@ Since pre-1.0.0.
 #]=======================================================================]
 
 include(CMakeParseArguments)
+include(${CMAKE_CURRENT_LIST_DIR}/QtVersionOption.cmake)
+
 
 # Copied from FindGettext.cmake
 function(_ecm_qm_get_unique_target_name _name _unique_name)
@@ -143,7 +145,7 @@ function(ecm_process_po_files_as_qm lang)
     endif()
 
     # Find lrelease and lconvert
-    find_package(Qt5LinguistTools CONFIG REQUIRED)
+    find_package(Qt${QT_MAJOR_VERSION}LinguistTools CONFIG REQUIRED)
 
     if(TARGET Qt5::lconvert)
         set(lconvert_executable Qt5::lconvert)
diff --git a/modules/ECMQueryQmake.cmake b/modules/ECMQueryQmake.cmake
index 74a6df87..4d7f9543 100644
--- a/modules/ECMQueryQmake.cmake
+++ b/modules/ECMQueryQmake.cmake
@@ -1,4 +1,5 @@
-find_package(Qt5Core QUIET)
+include(${CMAKE_CURRENT_LIST_DIR}/QtVersionOption.cmake)
+find_package(Qt${QT_MAJOR_VERSION}Core QUIET)
 
 if (Qt5Core_FOUND)
     set(_qmake_executable_default "qmake-qt5")