Make
QCommandLineParser::add{Help,Version}Option()
QCommandLineOption::setDefaultValue()
QCommandLineOptionPrivate::setNames()
have transaction semantics: either they succeed, or they change nothing.
It's trivial to provide this guarantee, so do it.
Add a test for the surprising property that setDefaultValue("") resets
defaultValues() to an empty QStringList instead of one that contains
the empty string.
Change-Id: I61623019de3c7d2e52c24f42cc2e23ec5fddc4da
Reviewed-by: David Faure <david.faure@kdab.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>