mktag: avoid %td in format string

Since v1.7.0-rc0~34 (make "mktag" a built-in, 2010-01-22), git mktag
uses the C99-style %td format to print ptrdiff_t values.  It falls
back to %d when NO_C99_FORMAT is set, on the assumption that pre-C99
systems probably are using 32-bit pointers.

But many modern systems are 64-bit and

 * sometimes one wants to test the NO_C99_FORMAT fallbacks using a
   modern development platform;
 * some platforms (I'm looking at you, msvc) have not gotten with the
   program and are still C89-only.

These ptrdiff_t values are offsets from the beginning of a buffer, so
a size_t or uintmax_t would work about as well.  Use the latter so we
can take advantage of the PRIuMAX fallback in git-compat-util.h, even
on C99-challenged systems with 64-bit pointers.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/mktag.c

@@ -35,12 +35,6 @@ static int verify_object(const unsigned char *sha1, const char *expected_type)
 	return ret;
 }
 
-#ifdef NO_C99_FORMAT
-#define PD_FMT "%d"
-#else
-#define PD_FMT "%td"
-#endif
-
 static int verify_tag(char *buffer, unsigned long size)
 {
 	int typelen;
@@ -70,15 +64,18 @@ static int verify_tag(char *buffer, unsigned long size)
 	/* Verify tag-line */
 	tag_line = strchr(type_line, '\n');
 	if (!tag_line)
-		return error("char" PD_FMT ": could not find next \"\\n\"", type_line - buffer);
+		return error("char%"PRIuMAX": could not find next \"\\n\"",
+				(uintmax_t) (type_line - buffer));
 	tag_line++;
 	if (memcmp(tag_line, "tag ", 4) || tag_line[4] == '\n')
-		return error("char" PD_FMT ": no \"tag \" found", tag_line - buffer);
+		return error("char%"PRIuMAX": no \"tag \" found",
+				(uintmax_t) (tag_line - buffer));
 
 	/* Get the actual type */
 	typelen = tag_line - type_line - strlen("type \n");
 	if (typelen >= sizeof(type))
-		return error("char" PD_FMT ": type too long", type_line+5 - buffer);
+		return error("char%"PRIuMAX": type too long",
+				(uintmax_t) (type_line+5 - buffer));
 
 	memcpy(type, type_line+5, typelen);
 	type[typelen] = 0;
@@ -95,15 +92,16 @@ static int verify_tag(char *buffer, unsigned long size)
 			break;
 		if (c > ' ')
 			continue;
-		return error("char" PD_FMT ": could not verify tag name", tag_line - buffer);
+		return error("char%"PRIuMAX": could not verify tag name",
+				(uintmax_t) (tag_line - buffer));
 	}
 
 	/* Verify the tagger line */
 	tagger_line = tag_line;
 
 	if (memcmp(tagger_line, "tagger ", 7))
-		return error("char" PD_FMT ": could not find \"tagger \"",
-			tagger_line - buffer);
+		return error("char%"PRIuMAX": could not find \"tagger \"",
+			(uintmax_t) (tagger_line - buffer));
 
 	/*
 	 * Check for correct form for name and email
@@ -115,44 +113,42 @@ static int verify_tag(char *buffer, unsigned long size)
 	if (!(lb = strstr(tagger_line, " <")) || !(rb = strstr(lb+2, "> ")) ||
 		strpbrk(tagger_line, "<>\n") != lb+1 ||
 		strpbrk(lb+2, "><\n ") != rb)
-		return error("char" PD_FMT ": malformed tagger field",
-			tagger_line - buffer);
+		return error("char%"PRIuMAX": malformed tagger field",
+			(uintmax_t) (tagger_line - buffer));
 
 	/* Check for author name, at least one character, space is acceptable */
 	if (lb == tagger_line)
-		return error("char" PD_FMT ": missing tagger name",
-			tagger_line - buffer);
+		return error("char%"PRIuMAX": missing tagger name",
+			(uintmax_t) (tagger_line - buffer));
 
 	/* timestamp, 1 or more digits followed by space */
 	tagger_line = rb + 2;
 	if (!(len = strspn(tagger_line, "0123456789")))
-		return error("char" PD_FMT ": missing tag timestamp",
-			tagger_line - buffer);
+		return error("char%"PRIuMAX": missing tag timestamp",
+			(uintmax_t) (tagger_line - buffer));
 	tagger_line += len;
 	if (*tagger_line != ' ')
-		return error("char" PD_FMT ": malformed tag timestamp",
-			tagger_line - buffer);
+		return error("char%"PRIuMAX": malformed tag timestamp",
+			(uintmax_t) (tagger_line - buffer));
 	tagger_line++;
 
 	/* timezone, 5 digits [+-]hhmm, max. 1400 */
 	if (!((tagger_line[0] == '+' || tagger_line[0] == '-') &&
 	      strspn(tagger_line+1, "0123456789") == 4 &&
 	      tagger_line[5] == '\n' && atoi(tagger_line+1) <= 1400))
-		return error("char" PD_FMT ": malformed tag timezone",
-			tagger_line - buffer);
+		return error("char%"PRIuMAX": malformed tag timezone",
+			(uintmax_t) (tagger_line - buffer));
 	tagger_line += 6;
 
 	/* Verify the blank line separating the header from the body */
 	if (*tagger_line != '\n')
-		return error("char" PD_FMT ": trailing garbage in tag header",
-			tagger_line - buffer);
+		return error("char%"PRIuMAX": trailing garbage in tag header",
+			(uintmax_t) (tagger_line - buffer));
 
 	/* The actual stuff afterwards we don't care about.. */
 	return 0;
 }
 
-#undef PD_FMT
-
 int cmd_mktag(int argc, const char **argv, const char *prefix)
 {
 	struct strbuf buf = STRBUF_INIT;