When comparing whether a path matches a directory rule, we pass the both the path and directory name to `fnmatch` with `GIT_ATTR_FNMATCH_DIRECTORY` being set. `fnmatch` expects the pattern to contain no trailing directory '/', which is why we try to always strip patterns of trailing slashes. We do not handle that case correctly though when the pattern itself has trailing spaces, causing the match to fail. Fix the issue by stripping trailing spaces and tabs for a rule previous to checking whether the pattern is a directory pattern with a trailing '/'. This replaces the whitespace-stripping in our ignore file parsing code, which was stripping whitespaces too late. Add a test to catch future breakage.
When computing negative ignores, we throw away any rule which does not
undo a previous rule to optimize. But on case insensitive file systems,
we need to keep in mind that a negative ignore can also undo a previous
rule with different case, which we did not yet honor while determining
whether a rule undoes a previous one. So in the following example, we
fail to unignore the "/Case" directory:
/case
!/Case
Make both paths checking whether a plain- or wildcard-based rule undo a
previous rule aware of case-insensitivity. This fixes the described
issue.
Ignore rules allow for reverting a previously ignored rule by prefixing it with an exclamation mark. As such, a negative rule can only override previously ignored files. While computing all ignore patterns, we try to use this fact to optimize away some negative rules which do not override any previous patterns, as they won't change the outcome anyway. In some cases, though, this optimization causes us to get the actual ignores wrong for some files. This may happen whenever the pattern contains a wildcard, as we are unable to reason about whether a pattern overrides a previous pattern in a sane way. This happens for example in the case where a gitignore file contains "*.c" and "!src/*.c", where we wouldn't un-ignore files inside of the "src/" subdirectory. In this case, the first solution coming to mind may be to just strip the "src/" prefix and simply compare the basenames. While that would work here, it would stop working as soon as the basename pattern itself is different, like for example with "*x.c" and "!src/*.c. As such, we settle for the easier fix of just not optimizing away rules that contain a wildcard.
Provide more detailed messages when conditions pass or fail unexpectedly. In particular, this provides the error messages when a test fails with a different error code than was expected.
In order to match the star-star, we disable the flag that's looking for a single path element, but that leads to searching for the pattern in the middle of elements in the input string. Mark when we're handing a star-star so we jump over the elements in our attempt to match the part of the pattern that comes after the star-star. While here, tighten up the check so we don't allow invalid rules through.