Re: [PATCH 1/5] treewide: rename 'struct exclude' to 'struct path_pattern'

Jeff King [off-list ref] writes:

I wonder if there's a name that could more clearly distinguish the two.
Or if it's sufficient to just become Git jargon that "pathspec" is the
command-line one and "path_pattern" is the file-based one (we're at
least pretty consistent about the former already).

I think one could also make an argument that the name collision is a
sign that these two things should actually share both syntax and
implementation, since we're exposing too similar-but-not-quite versions
of the same idea to users. But given the compatibility issues, it's
probably not worth changing the user facing parts at this point (and I
also haven't thought too hard about it; there may be reasons why the two
_should_ differ).

Hmph.  I did not realize there are so many differences X-<.  

A pathspec is relative to $CWD, and there is a syntax, i.e.
prefixing with ":(top)", to make it relative to the root level.  An
entry in a .gitignore file will never affect paths outside the
directory the file appears in.  And there should never be such a
mechanism to allow it.

An entry without slash in .gitignore is a basename match, and there
is a syntax i.e. prefixing with "/", to anchor it to a single
directory.  A pathspec without slash also can be a basename match
(e.g. "*.c" matches "a/b.c" as well as "d.c").  A pathspec with a
slash can be made to tail-match (e.g. "**/*.c" matches "a/b.c",
"a/b/c.c", etc.) but I do not think of a way to make an entry with a
slash in a .gitignore file a tail-match the same way.  I do not think
this is intended but merely a missing feature.

So, yes, eventually we may want to make them more similar, but I
suspect that there are some things that should be in one but never
be in the other.