[PATCH] commit-graph: fix some "plain integer as NULL pointer" warnings

[Ramsay Jones]

Signed-off-by: Ramsay Jones <ram...@ramsayjones.plus.com>
---

Hi Derrick,

If you need to re-roll your 'ds/commit-graph' branch, could you
please squash this into the relevant patches (corresponding to
commits 0fd2d95ee6 ["commit-graph: implement --set-latest"],
a33b9b79ff ["commit-graph: implement --delete-expired"] and finally
commit b534f9e961 ["commit-graph: implement git commit-graph read"]).

Also, I note that two symbols are only used in commit-graph.c but
are declared extern. Namely 'commit_graph' (declared line #42) and
'prepare_commit_graph' (declared line #212). Do these symbols need
to be extern (in future patches, perhaps)?

Thanks!

ATB,
Ramsay Jones

 builtin/commit-graph.c | 2 +-
 commit-graph.c         | 8 ++++----
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/builtin/commit-graph.c b/builtin/commit-graph.c
index be1883f1b..efdb003ca 100644
--- a/builtin/commit-graph.c
+++ b/builtin/commit-graph.c
@@ -33,7 +33,7 @@ static struct opts_commit_graph {
 
 static int graph_read(int argc, const char **argv)
 {
-       struct commit_graph *graph = 0;
+       struct commit_graph *graph = NULL;
        struct strbuf full_path = STRBUF_INIT;
 
        static struct option builtin_commit_graph_read_options[] = {
diff --git a/commit-graph.c b/commit-graph.c
index fc5ee7e99..c2f443436 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -45,7 +45,7 @@ char *get_graph_latest_filename(const char *obj_dir)
 {
        struct strbuf fname = STRBUF_INIT;
        strbuf_addf(&fname, "%s/info/graph-latest", obj_dir);
-       return strbuf_detach(&fname, 0);
+       return strbuf_detach(&fname, NULL);
 }
 
 char *get_graph_latest_contents(const char *obj_dir)
@@ -60,7 +60,7 @@ char *get_graph_latest_contents(const char *obj_dir)
        FREE_AND_NULL(fname);
 
        if (!f)
-               return 0;
+               return NULL;
 
        while (!feof(f)) {
                if (fgets(buf, sizeof(buf), f))
@@ -95,10 +95,10 @@ struct commit_graph *load_commit_graph_one(const char 
*graph_file)
        unsigned char graph_version, hash_version;
 
        if (fd < 0)
-               return 0;
+               return NULL;
        if (fstat(fd, &st)) {
                close(fd);
-               return 0;
+               return NULL;
        }
        graph_size = xsize_t(st.st_size);
 
-- 
2.16.0