[PATCH v5] builtin/diff-files: convert ad hoc option parsing to parse-options API

[Edson <edsonwasswa54@gmail.com>]

From: Wasswa Edson <edsonwasswa54@gmail.com>

The cmd_diff_files() function manually parses --base, --ours, --theirs,
and -q options using a hand-rolled loop with strcmp() calls. This is
inconsistent with the rest of Git's codebase and lacks features provided
by the parse-options API such as auto-generated help text, git completion
support, and option abbreviation.

Convert this to use the parse-options API by:
- Adding option definitions using OPT_* macros
- Removing the manual parsing loop
- Using parse_options() for consistent argument handling

The --base, --ours, and --theirs options use PARSE_OPT_NONEG to prevent
negated forms (--no-base, etc.) which are not meaningful for merge stage
selection. This follows the pattern used in builtin/checkout.c for similar
stage selection options.

This makes the code more maintainable and brings it in line with Git's
coding standards.

Signed-off-by: Wasswa Edson <edsonwasswa54@gmail.com>
---
 builtin/diff-files.c | 39 ++++++++++++++++++++-------------------
 1 file changed, 20 insertions(+), 19 deletions(-)

diff --git a/builtin/diff-files.c b/builtin/diff-files.c
index ea91347ce2..e9e4907311 100644
--- a/builtin/diff-files.c
+++ b/builtin/diff-files.c
@@ -14,11 +14,12 @@
 #include "commit.h"
 #include "preload-index.h"
 #include "revision.h"
+#include "parse-options.h"
 
-static const char diff_files_usage[] =
-"git diff-files [-q] [-0 | -1 | -2 | -3 | -c | --cc] [<common-diff-options>] [<path>...]"
-"\n"
-COMMON_DIFF_OPTIONS_HELP;
+static const char * const diff_files_usage[] = {
+	"git diff-files [-q] [-0 | -1 | -2 | -3 | -c | --cc] [<common-diff-options>] [<path>...]",
+	NULL
+};
 
 int cmd_diff_files(int argc,
 		   const char **argv,
@@ -28,8 +29,19 @@ int cmd_diff_files(int argc,
 	struct rev_info rev;
 	int result;
 	unsigned options = 0;
+	struct option diff_files_options[] = {
+		OPT_SET_INT_F(0, "base", &rev.max_count,
+			      N_("show base version"), 1, PARSE_OPT_NONEG),
+		OPT_SET_INT_F(0, "ours", &rev.max_count,
+			      N_("show our version"), 2, PARSE_OPT_NONEG),
+		OPT_SET_INT_F(0, "theirs", &rev.max_count,
+			      N_("show their version"), 3, PARSE_OPT_NONEG),
+		OPT_BIT('q', NULL, &options,
+		       N_("be quiet"), DIFF_SILENT_ON_REMOVED),
+		OPT_END()
+	};
 
-	show_usage_if_asked(argc, argv, diff_files_usage);
+	show_usage_with_options_if_asked(argc, argv, diff_files_usage, diff_files_options);
 
 	repo_config(the_repository, git_diff_basic_config, NULL); /* no "diff" UI options */
 
@@ -48,19 +60,8 @@ int cmd_diff_files(int argc,
 	prefix = precompose_argv_prefix(argc, argv, prefix);
 
 	argc = setup_revisions(argc, argv, &rev, NULL);
-	while (1 < argc && argv[1][0] == '-') {
-		if (!strcmp(argv[1], "--base"))
-			rev.max_count = 1;
-		else if (!strcmp(argv[1], "--ours"))
-			rev.max_count = 2;
-		else if (!strcmp(argv[1], "--theirs"))
-			rev.max_count = 3;
-		else if (!strcmp(argv[1], "-q"))
-			options |= DIFF_SILENT_ON_REMOVED;
-		else
-			usage(diff_files_usage);
-		argv++; argc--;
-	}
+	argc = parse_options(argc, argv, prefix, diff_files_options,
+			     diff_files_usage, 0);
 	if (!rev.diffopt.output_format)
 		rev.diffopt.output_format = DIFF_FORMAT_RAW;
 	rev.diffopt.rotate_to_strict = 1;
@@ -73,7 +74,7 @@ int cmd_diff_files(int argc,
 	if (rev.pending.nr ||
 	    rev.min_age != -1 || rev.max_age != -1 ||
 	    3 < rev.max_count)
-		usage(diff_files_usage);
+		usage_with_options(diff_files_usage, diff_files_options);
 
 	/*
 	 * "diff-files --base -p" should not combine merges because it
-- 
2.46.0.windows.1