I realise that this is not a real-world problem right now, as all the translation files are empty, but I want to change how the IDE is built, and make sure that I do not make this any worse than it already is, so spent some time tracking down what was going on.

And to capture the things I tried, and learned.

I added some debug output to main.cpp, to investigate the behaviour of the translation code - and this is what I got:

QLocale::system().name() = en_GB
QLibraryInfo::location(QLibraryInfo::TranslationsPath) = /Users/clare/Documents/develop/Audio/SuperCollider/build/Install/SuperCollider/SuperCollider.app/Contents/translations
ideTranslationPath = /Users/clare/Documents/develop/Audio/SuperCollider/build/Install/SuperCollider/SuperCollider.app/Contents/Resources/translations
QLocale::system().name() = en_GB
QLocale::languageToString( QLocale::system().language() ) = English
QLocale::countryToString( QLocale::system().country() ) = United Kingdom
ideTranslationFile = scide_en_GB

Things that are really weird in this:

• I have changed the system language to French and rebooted - lots of other applications show a French UI, yet the above output (obtained by double-clicking on the application icon, not launching from the terminal) still shows English
• The filenames editors/sc-ide/translations/ have 2-character language names, e.g. scide_fr.ts - but QLocale::system().name() is producing 5 chars i.e. en_GB

If I hard-code ideTranslationFile to be scide_fr then my hacked translation file is loaded correctly.

I think the answer is to change SuperCollider so that it does not identify the translation filename to use, and instead defers to Qt to use the QLocale to search for a range of valid file names.

This overload looks to be what is needed:

https://doc.qt.io/qt-5/qtranslator.html#load-1

bool QTranslator::load(const QLocale &locale, const QString &filename, 
    const QString &prefix = QString(), const QString &directory = QString(), 
    const QString &suffix = QString())

This looks to be useful example code:

https://github.com/KDAB/GammaRay/blob/master/common/translator.cpp#L53

Re this overload:

bool QTranslator::load(const QString &filename, const QString &directory = QString(), 
    const QString &search_delimiters = QString(), const QString &suffix = QString())

https://doc.qt.io/qt-5/qtranslator.html#load

It also does some mangling of file names to try and find alternative files... So I wonder whether the only problem is the language coming back as en_GB from the system instead of the fr_FR that I was expecting...

I am having a look at this... I don't seem to have permission to assign it to myself.

I added us both so I can help if anything comes up.

I've pushed a fix for this in claremacrae@3668bf9.

In order to set up a test of the change, I did the following:

1. Create a new translation file, scide_en.ts which was a copy of one of the existing ones
2. Add that new file to editors/sc-ide/CMakeLists.txt
3. Copy the text below in to editors/sc-ide/translations/hack_translation.sh
4. chmod a+x hack_translation.sh and run it
5. Build the install target, to include all the hacked translations

Then to actually test it, on a Mac:

1. Change the default Language & Region to French
   • There is no need to reboot the Mac. Just restarting SuperCollider is enough to pick up the new language
2. Start SuperCollider and confirm that all the menu items and widgets are called scide_fr.ts
3. Switch language to German, restart SuperCollider, and test that UI contains scide_de.ts
4. Switch to English, repeat, and test that UI contains scide_en.ts

# Copy in to editors/sc-ide/translations/hack_translation.sh
# This edits each .ts file so that it is obvious which language file was loaded
for file in *.ts ; do
  cat <<EOF > sedscr
s|<translation type="unfinished"></translation>|<translation>$file</translation>|
EOF
  sed -i.bak -f sedscr $file
  rm ${file}.bak
done
rm sedscr

@joshpar If you feel it's appropriate, please could you review the PR for this - #4620 - and if possible, merge it, as it's a precursor to my making a PR for #4617?

I've picked this up again... Right now, when I create an install on my Mac, there is no translations folder in

build/Install/SuperCollider/SuperCollider.app/Contents/Resources/

This needs debugging before I can reinstate my code to make sure that the translations are found....