[PATCH 0/4] fix make sparse warning

It's happened that I tried to run make check on project that support autoconf. Git's Makefile told me to run `make sparse` instead.

I /think/ if we have a rule in Makefile, we should adhere to it. I also fix another change in ds/blame-on-bloom, which I think it's worth to fix, see: <20200423133937.GA1984@danh.dev>

This series is developed from latest master.

It's conflicted when merge down next and pu.

For next, please ignore the conflict with fmt-merge-msg.c and apply [5/4] instead.

For pu, reftable.c has too much warnings, I'm too lazy to look into it.

Đoàn Trần Công Danh (4):
  C: s/0/NULL/ for pointer type
  compat/regex: silence `make sparse` warning
  graph.c: limit linkage of internal variable
  progress.c: silence cgcc suggestion about internal linkage

 add-interactive.c                   | 2 +-
 builtin/fmt-merge-msg.c             | 2 +-
 compat/regex/regex.c                | 1 +
 compat/regex/regex_internal.c       | 2 +-
 compat/regex/regex_internal.h       | 5 ++---
 graph.c                             | 2 +-
 log-tree.c                          | 4 ++--
 progress.c                          | 2 ++
 range-diff.c                        | 2 +-
 t/helper/test-parse-pathspec-file.c | 6 +++---
 10 files changed, 15 insertions(+), 13 deletions(-)