I asked about this elsewhere with no response, so I gather it can't be done yet.
Since this part of the forum is for "mods to the IDE" I suggest this:
Make the compiler flags configurable (eg. an entry in preferences.txt). That way you can ramp up warning levels, change the optimization amount, and do other similar and useful things.
The default could be the current behaviour, but this part could be modified:
I tried to use low-level gcc with make, and whilst I understand how they work together, I see that the default IDE does quite a bit of work behind the scenes. It seemed a shame to throw all that away, just to get some extra warnings, but it is always nice to have other options.
Thanks again, obviously there are lots of ways of approaching this.