Does your friend have an iPhone? The default iOS keyboard has automatically converted double dashes into an emdash for at least seven years now.
I think Google docs does this too, which drives me up the wall when I'm trying to write `command --foo=bar` and it turns it into an M-dash which obviously doesn't work.
I think Google docs does this too, which drives me up the wall when I'm trying to write `command --foo=bar` and it turns it into an M-dash which obviously doesn't work.