Which airlines will cancel the return leg (and intermediate legs if any) of a flight if you do not use the outward portion? This is assuming you bought outward and return as one transaction, rather than buying them separately.
Airlines are apparently notorious for cancelling return legs without warning in these circumstances. See for example https://www.independent.co.uk/travel/news-and-advice/which-airline-no-show-flight-clause-cancel-no-refund-air-travel-a8978801.html
However I recently was able to travel with Vueling having missed the outbound flight, arrived at my destination by other means and then used the return half of the ticket to get home. I checked with Vueling and they definitely have a policy of not cancelling such return tickets.
Similarly Ryanair say "You don't need to notify us if you are unable to travel and if you can’t use your outbound flight, you can still use your return flight." https://help.ryanair.com/hc/en-us/articles/360017824978-Refund-Policy
So my question is, does anyone have a list of which airlines will cancel return flights and which will not?