Merge branch 'rs/parse-options-negation-help'

"git cmd -h" learned to signal which options can be negated by
listing such options like "--[no-]opt".

* rs/parse-options-negation-help:
  parse-options: simplify usage_padding()
  parse-options: no --[no-]no-...
  parse-options: factor out usage_indent() and usage_padding()
  parse-options: show negatability of options in short help
  t1502: test option negation
  t1502: move optionspec help output to a file
  t1502, docs: disallow --no-help
  subtree: disallow --no-{help,quiet,debug,branch,message}

1 files changed, 50 insertions, 19 deletions

diff --git a/parse-options.c b/parse-options.c
index 60224cf8d0..76d2e76b49 100644
--- a/parse-options.c
+++ b/parse-options.c
@@ -1023,14 +1023,37 @@ static int usage_argh(const struct option *opts, FILE *outfile)
 	return utf8_fprintf(outfile, s, opts->argh ? _(opts->argh) : _("..."));
 }
 
-#define USAGE_OPTS_WIDTH 24
-#define USAGE_GAP         2
+static int usage_indent(FILE *outfile)
+{
+	return fprintf(outfile, "    ");
+}
+
+#define USAGE_OPTS_WIDTH 26
+
+static void usage_padding(FILE *outfile, size_t pos)
+{
+	if (pos < USAGE_OPTS_WIDTH)
+		fprintf(outfile, "%*s", USAGE_OPTS_WIDTH - (int)pos, "");
+	else
+		fprintf(outfile, "\n%*s", USAGE_OPTS_WIDTH, "");
+}
+
+static const struct option *find_option_by_long_name(const struct option *opts,
+						     const char *long_name)
+{
+	for (; opts->type != OPTION_END; opts++) {
+		if (opts->long_name && !strcmp(opts->long_name, long_name))
+			return opts;
+	}
+	return NULL;
+}
 
 static enum parse_opt_result usage_with_options_internal(struct parse_opt_ctx_t *ctx,
 							 const char * const *usagestr,
 							 const struct option *opts,
 							 int full, int err)
 {
+	const struct option *all_opts = opts;
 	FILE *outfile = err ? stderr : stdout;
 	int need_newline;
 
@@ -1111,8 +1134,8 @@ static enum parse_opt_result usage_with_options_internal(struct parse_opt_ctx_t
 
 	for (; opts->type != OPTION_END; opts++) {
 		size_t pos;
-		int pad;
 		const char *cp, *np;
+		const char *positive_name = NULL;
 
 		if (opts->type == OPTION_SUBCOMMAND)
 			continue;
@@ -1131,7 +1154,7 @@ static enum parse_opt_result usage_with_options_internal(struct parse_opt_ctx_t
 			need_newline = 0;
 		}
 
-		pos = fprintf(outfile, "    ");
+		pos = usage_indent(outfile);
 		if (opts->short_name) {
 			if (opts->flags & PARSE_OPT_NODASH)
 				pos += fprintf(outfile, "%c", opts->short_name);
@@ -1140,8 +1163,15 @@ static enum parse_opt_result usage_with_options_internal(struct parse_opt_ctx_t
 		}
 		if (opts->long_name && opts->short_name)
 			pos += fprintf(outfile, ", ");
-		if (opts->long_name)
-			pos += fprintf(outfile, "--%s", opts->long_name);
+		if (opts->long_name) {
+			const char *long_name = opts->long_name;
+			if ((opts->flags & PARSE_OPT_NONEG) ||
+			    skip_prefix(long_name, "no-", &positive_name))
+				pos += fprintf(outfile, "--%s", long_name);
+			else
+				pos += fprintf(outfile, "--[no-]%s", long_name);
+		}
+
 		if (opts->type == OPTION_NUMBER)
 			pos += utf8_fprintf(outfile, _("-NUM"));
 
@@ -1149,16 +1179,8 @@ static enum parse_opt_result usage_with_options_internal(struct parse_opt_ctx_t
 		    !(opts->flags & PARSE_OPT_NOARG))
 			pos += usage_argh(opts, outfile);
 
-		if (pos == USAGE_OPTS_WIDTH + 1)
-			pad = -1;
-		else if (pos <= USAGE_OPTS_WIDTH)
-			pad = USAGE_OPTS_WIDTH - pos;
-		else {
-			fputc('\n', outfile);
-			pad = USAGE_OPTS_WIDTH;
-		}
 		if (opts->type == OPTION_ALIAS) {
-			fprintf(outfile, "%*s", pad + USAGE_GAP, "");
+			usage_padding(outfile, pos);
 			fprintf_ln(outfile, _("alias of --%s"),
 				   (const char *)opts->value);
 			continue;
@@ -1166,12 +1188,21 @@ static enum parse_opt_result usage_with_options_internal(struct parse_opt_ctx_t
 
 		for (cp = _(opts->help); *cp; cp = np) {
 			np = strchrnul(cp, '\n');
-			fprintf(outfile,
-				"%*s%.*s\n", pad + USAGE_GAP, "",
-				(int)(np - cp), cp);
+			usage_padding(outfile, pos);
+			fprintf(outfile, "%.*s\n", (int)(np - cp), cp);
 			if (*np)
 				np++;
-			pad = USAGE_OPTS_WIDTH;
+			pos = 0;
+		}
+
+		if (positive_name) {
+			if (find_option_by_long_name(all_opts, positive_name))
+				continue;
+			pos = usage_indent(outfile);
+			pos += fprintf(outfile, "--%s", positive_name);
+			usage_padding(outfile, pos);
+			fprintf_ln(outfile, _("opposite of --no-%s"),
+				   positive_name);
 		}
 	}
 	fputc('\n', outfile);