[PATCH 4/6] *.h: add a few missing __attribute__((format))

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

Add missing format attributes to those function that were missing
them.

In the case of advice_enabled() this revealed a trivial issue
introduced in b3b18d16213 (advice: revamp advise API, 2020-03-02). We
treated the argv[1] as a format string, but did not intend to do
so. Let's use "%s" and pass argv[1] as an argument instead.

For strbuf_addftime() let's add a strftime() format checker. Our
function understands the non-portable %z and %Z, see
c3fbf81a853 (strbuf: let strbuf_addftime handle %z and %Z itself,
2017-06-15).

That might be an issue in theory, but in practice we have existing
codepath that supplies a fixed string to strbuf_addftime(). We're
unlikely to run into the "%z" and "%Z" case at all, since it's used by
date.c and passed via e.g. "git log --date=<format>".

In fact, we had no in-tree user of strbuf_addftime() with an inline
fixed format string at all. A subsequent commit will tweak an existing
one to use the format checking.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 advice.h               | 1 +
 cache.h                | 1 +
 compat/win32/syslog.h  | 1 +
 quote.h                | 1 +
 strbuf.h               | 2 ++
 t/helper/test-advise.c | 2 +-
 6 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/advice.h b/advice.h
index bd26c385d00..9f8ffc73546 100644
--- a/advice.h
+++ b/advice.h
@@ -90,6 +90,7 @@ int advice_enabled(enum advice_type type);
 /**
  * Checks the visibility of the advice before printing.
  */
+__attribute__((format (printf, 2, 3)))
 void advise_if_enabled(enum advice_type type, const char *advice, ...);
 
 int error_resolve_conflict(const char *me);
diff --git a/cache.h b/cache.h
index ba04ff8bd36..f9aed2d45c7 100644
--- a/cache.h
+++ b/cache.h
@@ -1385,6 +1385,7 @@ enum get_oid_result {
 };
 
 int repo_get_oid(struct repository *r, const char *str, struct object_id *oid);
+__attribute__((format (printf, 2, 3)))
 int get_oidf(struct object_id *oid, const char *fmt, ...);
 int repo_get_oid_commit(struct repository *r, const char *str, struct object_id *oid);
 int repo_get_oid_committish(struct repository *r, const char *str, struct object_id *oid);
diff --git a/compat/win32/syslog.h b/compat/win32/syslog.h
index 70daa7c08b8..28e2c96c52d 100644
--- a/compat/win32/syslog.h
+++ b/compat/win32/syslog.h
@@ -15,6 +15,7 @@
 #define LOG_DAEMON  (3<<3)
 
 void openlog(const char *ident, int logopt, int facility);
+__attribute__((format (printf, 2, 3)))
 void syslog(int priority, const char *fmt, ...);
 
 #endif /* SYSLOG_H */
diff --git a/quote.h b/quote.h
index 768cc6338e2..049d8dd0b3d 100644
--- a/quote.h
+++ b/quote.h
@@ -31,6 +31,7 @@ struct strbuf;
 
 void sq_quote_buf(struct strbuf *, const char *src);
 void sq_quote_argv(struct strbuf *, const char **argv);
+__attribute__((format (printf, 2, 3)))
 void sq_quotef(struct strbuf *, const char *fmt, ...);
 
 /*
diff --git a/strbuf.h b/strbuf.h
index 223ee2094af..215fbdd64bc 100644
--- a/strbuf.h
+++ b/strbuf.h
@@ -263,6 +263,7 @@ static inline void strbuf_insertstr(struct strbuf *sb, size_t pos,
 void strbuf_vinsertf(struct strbuf *sb, size_t pos, const char *fmt,
 		     va_list ap);
 
+__attribute__((format (printf, 3, 4)))
 void strbuf_insertf(struct strbuf *sb, size_t pos, const char *fmt, ...);
 
 /**
@@ -425,6 +426,7 @@ void strbuf_vaddf(struct strbuf *sb, const char *fmt, va_list ap);
  * `suppress_tz_name`, when set, expands %Z internally to the empty
  * string rather than passing it to `strftime`.
  */
+__attribute__((format (strftime, 2, 0)))
 void strbuf_addftime(struct strbuf *sb, const char *fmt,
 		    const struct tm *tm, int tz_offset,
 		    int suppress_tz_name);
diff --git a/t/helper/test-advise.c b/t/helper/test-advise.c
index a7043df1d38..cb881139f73 100644
--- a/t/helper/test-advise.c
+++ b/t/helper/test-advise.c
@@ -16,7 +16,7 @@ int cmd__advise_if_enabled(int argc, const char **argv)
 	 * selected here and in t0018 where this command is being
 	 * executed.
 	 */
-	advise_if_enabled(ADVICE_NESTED_TAG, argv[1]);
+	advise_if_enabled(ADVICE_NESTED_TAG, "%s", argv[1]);
 
 	return 0;
 }
-- 
2.32.0.636.g43e71d69cff