New lint: inspect-then-for_each on iterators should be simplified #5209
Description
Inspired by the change made in https://github.com/rust-lang/rust/pull/69022/files#diff-d1ff3aad2daeb77432493d91c41b722bL147
When an inspect is followed by for_each, that's the same as just doing the thing in the inspect at the beginning of the closure in the for_each.
It's possible that this should only be suggested when a brace-bodied closure is already being passed to for_each, like
.inspect(|x| do_something(x, 2))
.for_each(|x| {
do_more(x);
update_something(x);
});
which can just be
.for_each(|x| {
do_something(x, 2);
do_more(x);
update_something(x);
});
But not for something like .inspect(foo).for_each(bar), where it's not obvious that the closure is better. (It's not bad, but not an obvious improvement.)