I have a pair of trousers from a brand named apricot. The legs are not sewn together but overlap and are floaty lovely. they have an elasticated back waistband.
Similar to this: Paisley Wrap Split Leg Trousers | Apricot UK
Has anyone seen a pattern to make some?
Should be easy to draft from a regular pair of pants.
Line up the side seams of front and back leg patterns, spread out flat. Trace the back pattern, and include about 1/2 of the front pattern. Then repeat for the front, adding about 1/2 of the back pattern.
Cut from fabric, hem the loose edges, then assemble.
I just googled, this looks reasonable.
Ohh, you can wear those pants so many ways! Who knew?
Men’s kimono pants maybe? My brain is thinking you could sew up the sides
They are very versatile - but how do you go to the toilet? 
I always think about getting a playsuit type thing but same question!
Just because I didn’t see it listed yet: this type of pant is often called “Thai Fishermen’s Pants,” and searching that term will turn up a TON of free patterns, tutorials, and walk-throughs on websites, as well as actual patterns, such as " Simplicity Easy-To-Sew Sewing Pattern 8134," which includes an elasticized waistband on the stationary/front part of the pants, rather than the double wrap version that is more traditional (and also, yes, exceptionally hard to go to the bathroom in carefully in a public place). 
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Untie the front, swoop it up and bunch it about at your belly. Sort of like what you would do with a long skirt, I suppose.
I have one pair that I really love wearing in summer.
Yeah, I’ve never had issues either.
Years ago, I made some similar to the first link @Magpie shared. Very comfortable and no issues using the washroom, as others have already said.