Merge branch 'jk/pretty-empty-format'

"git log --pretty/format=" with an empty format string did not mean
the more obvious "No output whatsoever" but "Use default format",
which was counterintuitive.

* jk/pretty-empty-format:
  pretty: make empty userformats truly empty
  pretty: treat "--format=" as an empty userformat
  revision: drop useless string offset when parsing "--pretty"

combine-diff.c

@@ -1407,7 +1407,8 @@ void diff_tree_combined(const unsigned char *sha1,
 		show_log(rev);
 
 		if (rev->verbose_header && opt->output_format &&
-		    opt->output_format != DIFF_FORMAT_NO_OUTPUT)
+		    opt->output_format != DIFF_FORMAT_NO_OUTPUT &&
+		    !commit_format_is_empty(rev->commit_format))
 			printf("%s%c", diff_line_prefix(opt),
 			       opt->line_termination);
 	}

commit.h

@@ -159,6 +159,7 @@ extern void get_commit_format(const char *arg, struct rev_info *);
 extern const char *format_subject(struct strbuf *sb, const char *msg,
 				  const char *line_separator);
 extern void userformat_find_requirements(const char *fmt, struct userformat_want *w);
+extern int commit_format_is_empty(enum cmit_fmt);
 extern void format_commit_message(const struct commit *commit,
 				  const char *format, struct strbuf *sb,
 				  const struct pretty_print_context *context);

log-tree.c

@@ -649,7 +649,7 @@ void show_log(struct rev_info *opt)
 		graph_show_commit_msg(opt->graph, &msgbuf);
 	else
 		fwrite(msgbuf.buf, sizeof(char), msgbuf.len, stdout);
-	if (opt->use_terminator) {
+	if (opt->use_terminator && !commit_format_is_empty(opt->commit_format)) {
 		if (!opt->missing_newline)
 			graph_show_padding(opt->graph);
 		putchar(opt->diffopt.line_termination);
@@ -676,7 +676,8 @@ int log_tree_diff_flush(struct rev_info *opt)
 		show_log(opt);
 		if ((opt->diffopt.output_format & ~DIFF_FORMAT_NO_OUTPUT) &&
 		    opt->verbose_header &&
-		    opt->commit_format != CMIT_FMT_ONELINE) {
+		    opt->commit_format != CMIT_FMT_ONELINE &&
+		    !commit_format_is_empty(opt->commit_format)) {
 			/*
 			 * When showing a verbose header (i.e. log message),
 			 * and not in --pretty=oneline format, we would want

pretty.c

@@ -24,6 +24,11 @@ static size_t commit_formats_len;
 static size_t commit_formats_alloc;
 static struct cmt_fmt_map *find_commit_format(const char *sought);
 
+int commit_format_is_empty(enum cmit_fmt fmt)
+{
+	return fmt == CMIT_FMT_USERFORMAT && !*user_format;
+}
+
 static void save_user_format(struct rev_info *rev, const char *cp, int is_tformat)
 {
 	free(user_format);
@@ -146,7 +151,7 @@ void get_commit_format(const char *arg, struct rev_info *rev)
 	struct cmt_fmt_map *commit_format;
 
 	rev->use_terminator = 0;
-	if (!arg || !*arg) {
+	if (!arg) {
 		rev->commit_format = CMIT_FMT_DEFAULT;
 		return;
 	}
@@ -155,7 +160,7 @@ void get_commit_format(const char *arg, struct rev_info *rev)
 		return;
 	}
 
-	if (strchr(arg, '%')) {
+	if (!*arg || strchr(arg, '%')) {
 		save_user_format(rev, arg, 1);
 		return;
 	}

revision.c

@@ -1825,7 +1825,7 @@ static int handle_revision_opt(struct rev_info *revs, int argc, const char **arg
 	} else if (!strcmp(arg, "--pretty")) {
 		revs->verbose_header = 1;
 		revs->pretty_given = 1;
-		get_commit_format(arg+8, revs);
+		get_commit_format(NULL, revs);
 	} else if (starts_with(arg, "--pretty=") || starts_with(arg, "--format=")) {
 		/*
 		 * Detached form ("--pretty X" as opposed to "--pretty=X")