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.
#!/usr/bin/env python3
# Filter output by pyflakes to control which warnings we check
import re
import sys
lines = []
for line in sys.stdin:
# We blacklist tests that are too noisy for us
pats = [
r"undefined name 'WindowsError'",
r"redefinition of unused '[^']+' from line",
# for cffi, allow re-exports from pure.*
r"cffi/[^:]*:.*\bimport \*' used",
r"cffi/[^:]*:.*\*' imported but unused",
]
keep = True
for pat in pats:
if re.search(pat, line):
keep = False
break # pattern matches
if keep:
fn = line.split(':', 1)[0]
with open(fn, 'rb') as f:
data = f.read()
if b'no-' b'check-code' in data:
continue
lines.append(line)
for line in lines:
sys.stdout.write(line)
print()