`{flat_,}map_identity`: recognize (tuple) struct de- and restructuring

base check

same fields different struct

reordered fields

different paths to the same struct

same for tuple structs

style: use `zip`-the-function all over the place

makes the code a bit more concise by removing the need for explicit
`.iter()`

style: move precondition checking to the match guard

the match arms above put the "sanity" checks in the guard, and call only
`check_pat` in the body. With this commit, the (tuple) struct cases
follow that convention as well. Well, almost -- I think the ident check
belongs to the second category of checks, so I put it in the body as
well

misc: use `None` in the pattern directly

this'll probably be marginally faster thanks to the equality check being
now structural

move the tests to the right file

0 files changed, 0 insertions, 0 deletions