diff: deprecate -q option to diff-files

This reimplements the ancient "-q" option to "git diff-files" that
was inherited from "show-diff -q" in terms of "--diff-filter=d".  We
will be deprecating the "-q" option, so let's issue a warning when
we do so.

Incidentally this also tentatively fixes "git diff --no-index" to
honor "-q" and hide deletions; the use will get the same warning.

We should remove the support for "-q" in a future version but it is
not that urgent.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff-lib.c

@@ -86,10 +86,12 @@ int run_diff_files(struct rev_info *revs, unsigned int option)
 {
 	int entries, i;
 	int diff_unmerged_stage = revs->max_count;
-	int silent_on_removed = option & DIFF_SILENT_ON_REMOVED;
 	unsigned ce_option = ((option & DIFF_RACY_IS_MODIFIED)
 			      ? CE_MATCH_RACY_IS_DIRTY : 0);
 
+	if (option & DIFF_SILENT_ON_REMOVED)
+		handle_deprecated_show_diff_q(&revs->diffopt);
+
 	diff_set_mnemonic_prefix(&revs->diffopt, "i/", "w/");
 
 	if (diff_unmerged_stage < 0)
@@ -136,8 +138,6 @@ int run_diff_files(struct rev_info *revs, unsigned int option)
 					perror(ce->name);
 					continue;
 				}
-				if (silent_on_removed)
-					continue;
 				wt_mode = 0;
 			}
 			dpath->mode = wt_mode;
@@ -203,8 +203,6 @@ int run_diff_files(struct rev_info *revs, unsigned int option)
 				perror(ce->name);
 				continue;
 			}
-			if (silent_on_removed)
-				continue;
 			diff_addremove(&revs->diffopt, '-', ce->ce_mode,
 				       ce->sha1, !is_null_sha1(ce->sha1),
 				       ce->name, 0);

diff-no-index.c

@@ -187,7 +187,7 @@ void diff_no_index(struct rev_info *revs,
 {
 	int i, prefixlen;
 	int no_index = 0;
-	unsigned options = 0;
+	unsigned deprecated_show_diff_q_option_used = 0;
 	const char *paths[2];
 
 	/* Were we asked to do --no-index explicitly? */
@@ -225,7 +225,7 @@ void diff_no_index(struct rev_info *revs,
 		if (!strcmp(argv[i], "--no-index"))
 			i++;
 		else if (!strcmp(argv[i], "-q")) {
-			options |= DIFF_SILENT_ON_REMOVED;
+			deprecated_show_diff_q_option_used = 1;
 			i++;
 		}
 		else if (!strcmp(argv[i], "--"))
@@ -260,6 +260,9 @@ void diff_no_index(struct rev_info *revs,
 	revs->max_count = -2;
 	diff_setup_done(&revs->diffopt);
 
+	if (deprecated_show_diff_q_option_used)
+		handle_deprecated_show_diff_q(&revs->diffopt);
+
 	setup_diff_pager(&revs->diffopt);
 	DIFF_OPT_SET(&revs->diffopt, EXIT_WITH_STATUS);
 

diff.c

@@ -3570,6 +3570,14 @@ static int parse_diff_filter_opt(const char *optarg, struct diff_options *opt)
 	return 0;
 }
 
+/* Used only by "diff-files" and "diff --no-index" */
+void handle_deprecated_show_diff_q(struct diff_options *opt)
+{
+	warning("'diff -q' and 'diff-files -q' are deprecated.");
+	warning("Use 'diff --diff-filter=d' instead to ignore deleted filepairs.");
+	parse_diff_filter_opt("d", opt);
+}
+
 int diff_opt_parse(struct diff_options *options, const char **av, int ac)
 {
 	const char *arg = av[0];

diff.h

@@ -341,6 +341,8 @@ extern int parse_rename_score(const char **cp_p);
 
 extern long parse_algorithm_value(const char *value);
 
+extern void handle_deprecated_show_diff_q(struct diff_options *);
+
 extern int print_stat_summary(FILE *fp, int files,
 			      int insertions, int deletions);
 extern void setup_diff_pager(struct diff_options *);