yet another "old borrowck" bug around match default bindings
We were getting the type of the parameter from its pattern, but that didn't include adjustments. I did a `ripgrep` around and this seemed to be the only affected case.
The reason this didn't show up as an ICE earlier is that mem-categorization is lenient with respect to weird discrepancies. I am going to add more delay-span-bug calls shortly around that (I'll push onto the PR).
This example is an ICE, but I presume that there is a way to make a soundness example out of this -- it basically ignores borrows occuring inside match-default-bindings in a closure, though only if the implicit deref is at the top-level. It happens though that this occurs frequently in iterators, which often give a `&T` parameter.
Fixes#51415Fixes#49534
r? @eddyb
7dae5c0e06