Cannot deconstruct reference inside match on reference—why?

[steffahn]

I answered what was essentially the same question fairly recently here:

Reference of Tuple and Tuple of Reference

Right, match ergonomics is a bit different from what I imagine you might be imagining here: What you probably imagine is that let (PAT1, PAT2) = r; with r: &(S, T) will create a &S and match it against PAT1; as well as creating a &T and matching it against PAT2. That’s not what happens. Instead it’s just that the pattern is re-written in precisely two ways: a dereferencing step is introduced implicitly, so the pattern becomes a &(PAT1', PAT2') pattern the sub-patterns PAT1 and PAT2 would be …