qmake and generated qm files - qt

Question

What is the best (proper) way to organize compiled translations (*.qm) into resources?
*.qm files referred in qrc file and generated by two (three) extra targets this way:
trans_update.commands = lupdate $$_PRO_FILE_
trans_update.depends = $$_PRO_FILE_
trans_release.commands = lrelease $$_PRO_FILE_
trans_release.depends = trans_update $$TRANSLATIONS
translate.depends = trans_release
QMAKE_EXTRA_TARGETS += trans_update trans_release translate deploy
CONFIG(release, debug|release) {
DESTDIR=release
PRE_TARGETDEPS += translate
}
but the problem is at the moment qmake runs first time, there're no qm files generated yet and make prints errors like:
RCC: Error in 'qml.qrc': Cannot find file ...
I don't like an idea of saving compiled qm files into VSC.
Is there a way to organize it nicely?

Answer 1

I like to point out a solution which I use in some projects. It might be far from perfect, but it works out nicely.
CONFIG(release, debug|release) {
TRANSLATION_TARGET_DIR = $${OUT_PWD}/release/translations
LANGUPD_OPTIONS = -locations relative -no-ui-lines
LANGREL_OPTIONS = -compress -nounfinished -removeidentical
} else {
TRANSLATION_TARGET_DIR = $${OUT_PWD}/debug/translations
LANGUPD_OPTIONS =
LANGREL_OPTIONS = -markuntranslated "MISS_TR "
}
isEmpty(QMAKE_LUPDATE) {
win32:LANGUPD = $$[QT_INSTALL_BINS]\lupdate.exe
else:LANGUPD = $$[QT_INSTALL_BINS]/lupdate
}
isEmpty(QMAKE_LRELEASE) {
win32:LANGREL = $$[QT_INSTALL_BINS]\lrelease.exe
else:LANGREL = $$[QT_INSTALL_BINS]/lrelease
}
langupd.command = \
$$LANGUPD $$LANGUPD_OPTIONS $$shell_path($$_PRO_FILE_) -ts $$_PRO_FILE_PWD_/$$TRANSLATIONS
langrel.depends = langupd
langrel.input = TRANSLATIONS
langrel.output = $$TRANSLATION_TARGET_DIR/${QMAKE_FILE_BASE}.qm
langrel.commands = \
$$LANGREL $$LANGREL_OPTIONS ${QMAKE_FILE_IN} -qm $$TRANSLATION_TARGET_DIR/${QMAKE_FILE_BASE}.qm
langrel.CONFIG += no_link
QMAKE_EXTRA_TARGETS += langupd
QMAKE_EXTRA_COMPILERS += langrel
PRE_TARGETDEPS += langupd compiler_langrel_make_all
There might be a sensful tweak to lupdate options because the various builds (release and debug) generate different *.ts files which then trigger a change in the used VCS.
I also like to guide the tended reader to an example where experts use it.

Answer 2

The recommended way -- which may not have been available at the time this question was originally asked would be to use
TRANSLATIONS += <your *.ts files>
CONFIG += lrelease embed_translations
If you really need/want to build the qm files separately, I'd point to what qmake does with the above config and adapt it according to your needs. See https://github.com/qt/qtbase/blob/5.15.2/mkspecs/features/lrelease.prf
(Basically, it creates and adds a list of resources to RESOURCES).