[PATCH/RFC 0/3] Support ignore rule "**" using wildmatch from rsync

I've been looking for something like this. Bash 4 has a similar feature, but it's GPL-3. rsync is also GPL-3. Luckily this feature was availble before the license change.

I'm not sure if we should import wildmatch just to support "**". It seems a nice and often requested feature. And the code looks more readable than compat/fnmatch, which is good since I don't think we can cherry pick from (gpl3) upstream.

We would need to add case folding support or convert "abc" to "[aA][bB][cC]". Performance vs fnmatch is another question but we could switch to wildmatch only in the presence of "**" if wildmatch perf sucks. Even pathspec may make use of this, thanks to pathspec magic.

I have not looked carefully at it and this series is more like a proof of concept than a candidate for 'pu'. Any comments in favor or oppose this?

Nguyễn Thái Ngọc Duy (3):
  Import wildmatch from rsync
  Integrate wildmatch to git
  gitignore: support "**" with wildmatch()

 Makefile                       |    3 +
 compat/wildmatch.c             |  356 ++++++++++++++++++++++++++++++++++++++++
 compat/wildmatch.h             |    6 +
 dir.c                          |   20 ++-
 dir.h                          |    1 +
 t/t3070-wildmatch.sh           |   27 +++
 t/t3070-wildmatch/wildtest.txt |  165 +++++++++++++++++++
 test-wildmatch.c               |  162 ++++++++++++++++++
 8 files changed, 736 insertions(+), 4 deletions(-)
 create mode 100644 compat/wildmatch.c
 create mode 100644 compat/wildmatch.h
 create mode 100755 t/t3070-wildmatch.sh
 create mode 100644 t/t3070-wildmatch/wildtest.txt
 create mode 100644 test-wildmatch.c