Merge branch 'jn/help-everywhere'

* jn/help-everywhere: (23 commits)
  diff --no-index: make the usage string less scary
  merge-{recursive,subtree}: use usagef() to print usage
  Introduce usagef() that takes a printf-style format
  Let 'git <command> -h' show usage without a git dir
  Show usage string for 'git http-push -h'
  Let 'git http-fetch -h' show usage outside any git repository
  Show usage string for 'git stripspace -h'
  Show usage string for 'git unpack-file -h'
  Show usage string for 'git show-index -h'
  Show usage string for 'git rev-parse -h'
  Show usage string for 'git merge-one-file -h'
  Show usage string for 'git mailsplit -h'
  Show usage string for 'git imap-send -h'
  Show usage string for 'git get-tar-commit-id -h'
  Show usage string for 'git fast-import -h'
  Show usage string for 'git check-ref-format -h'
  http-fetch: add missing initialization of argv0_path
  Show usage string for 'git show-ref -h'
  Show usage string for 'git merge-ours -h'
  Show usage string for 'git commit-tree -h'
  ...

Conflicts:
	imap-send.c

1 files changed, 13 insertions, 4 deletions

diff --git a/usage.c b/usage.c
index c488f3afcd..e307e01b99 100644
--- a/usage.c
+++ b/usage.c
@@ -12,9 +12,9 @@ static void report(const char *prefix, const char *err, va_list params)
 	fprintf(stderr, "%s%s\n", prefix, msg);
 }
 
-static NORETURN void usage_builtin(const char *err)
+static NORETURN void usage_builtin(const char *err, va_list params)
 {
-	fprintf(stderr, "usage: %s\n", err);
+	report("usage: ", err, params);
 	exit(129);
 }
 
@@ -36,7 +36,7 @@ static void warn_builtin(const char *warn, va_list params)
 
 /* If we are in a dlopen()ed .so write to a global variable would segfault
  * (ugh), so keep things static. */
-static NORETURN_PTR void (*usage_routine)(const char *err) = usage_builtin;
+static NORETURN_PTR void (*usage_routine)(const char *err, va_list params) = usage_builtin;
 static NORETURN_PTR void (*die_routine)(const char *err, va_list params) = die_builtin;
 static void (*error_routine)(const char *err, va_list params) = error_builtin;
 static void (*warn_routine)(const char *err, va_list params) = warn_builtin;
@@ -46,9 +46,18 @@ void set_die_routine(NORETURN_PTR void (*routine)(const char *err, va_list param
 	die_routine = routine;
 }
 
+void usagef(const char *err, ...)
+{
+	va_list params;
+
+	va_start(params, err);
+	usage_routine(err, params);
+	va_end(params);
+}
+
 void usage(const char *err)
 {
-	usage_routine(err);
+	usagef("%s", err);
 }
 
 void die(const char *err, ...)