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.

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  $ hg init repo

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  $ cd repo

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  $ "$PYTHON" -c 'open("a", "wb").write(b"confuse str.splitlines\nembedded\rnewline\n")'

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  $ hg ci -Ama -d '1 0'

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  adding a

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  $ echo clean diff >> a

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  $ hg ci -mb -d '2 0'

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  $ hg diff -r0 -r1

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  diff -r 107ba6f817b5 -r 310ce7989cdc a

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  --- a/a	Thu Jan 01 00:00:01 1970 +0000

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  +++ b/a	Thu Jan 01 00:00:02 1970 +0000

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  @@ -1,2 +1,3 @@

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   confuse str.splitlines

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   embedded\r (no-eol) (esc)

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  newline

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  +clean diff

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