make sure we remove obsolete entries from translations (#3995)

.github/workflows/release-windows.yml

@@ -71,7 +71,7 @@ jobs:
       - name: Create .qm
         run: |
           cd gui
-          lupdate gui.pro
+          lupdate gui.pro -no-obsolete
           lrelease gui.pro -removeidentical
 
       - name: Matchcompiler

gui/CMakeLists.txt

@@ -14,6 +14,7 @@ if (BUILD_GUI)
     file(GLOB tss  "*.ts")
     QT_WRAP_UI(uis_hdrs ${uis})
     QT_ADD_RESOURCES(resources "gui.qrc")
+    # TODO: passing "-no-obsolete" here breaks the translations
     QT_CREATE_TRANSLATION(qms ${CMAKE_CURRENT_SOURCE_DIR} ${tss})
     list(APPEND cppcheck-gui-deps ${hdrs} ${uis_hdrs} ${resources} ${qms})
     add_custom_target(gui-build-deps SOURCES ${cppcheck-gui-deps})

gui/readme.txt

@@ -61,10 +61,10 @@ and compile the translations. lupdate updates translations files from the code
 and lrelease compiles translation files use with the executable.
 
 To update translations:
-- run lupdate gui.pro to update the translation files to match the code. This
+- run "lupdate gui.pro -no-obsolete" to update the translation files to match the code. This
   command updates all the .ts files. Which can be then edited to translate
   the application.
 
 To compile translations:
-- run lrelease gui.pro to compile .ts files to .qm files which are used by the
+- run "lrelease gui.pro" to compile .ts files to .qm files which are used by the
   executable.