match: strengthen visit_children_set invariant, Recursive means "all files" My previous interpretation of "Recursive" was too relaxed: I thought it instructed the caller to do something like this: > you can stop calling `visit_children_set` because you'll need to descend into > every directory recursively, but you should still check every file if it > matches or not Whereas the real instruction seems to be: > I guarantee that everything in this subtree matches, you can stop > querying the matcher for all files and dirs altogether. The evidence to support this: - the test actually passes with the stronger invariant, revealing no exceptions from this rule - the implementation of `visit_children_set` for `DifferenceMatcher` clearly relies on this requirement, so it must hold for that not to lead to bugs.

match: fix the rust-side bug in visit_children_set for rootfilesin matchers The fix is checked by `test_pattern_matcher_visit_children_set` test, which is what caught the bug in the first place, but also by an end-to-end test that I made for this purpose. Accept the new results of Cargo tests Many of these were already annotated with "FIXME", which is a good sign.

match: fix the "visitdir" method on "rootfilesin" matchers This fixes just the Python side, the fix for the rust side will follow shortly.

match: rename RootFiles to RootFilesIn for more consistency

match: small tweak to PatternMatcher.visit_children_set This makes it a bit more efficient (avoid a computation in case of early return), and in my opinion clearer.

matchers: fix the bug in rust PatternMatcher that made it cut off early This brings the rust output in line with the Python output.

tests: add an end-to-end test to show a bug in `visit_children_set` Concretely, `rootfilesin` is completely broken with respect to `visit_children_set` optimization.