diff: spell DIFF_INDEX_CACHED out when calling run_diff_index()

Many callers of run_diff_index() passed literal "1" for the option
flag word, which should better be spelled out as DIFF_INDEX_CACHED
for readablity.  Everybody else passes "0" that can stay as-is.

The other bit in the option flag word is DIFF_INDEX_MERGE_BASE, but
curiously there is only one caller that can pass it, which is "git
diff-index --merge-base" itself---no internal callers uses the
feature.

A bit tricky call to the function is in builtin/submodule--helper.c
where the .cached member in a private struct is set/reset as a plain
Boolean flag, which happens to be "1" and happens to match the value
of DIFF_INDEX_CACHED.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

add-interactive.c

@@ -569,7 +569,7 @@ static int get_modified_files(struct repository *r,
 			copy_pathspec(&rev.prune_data, ps);
 
 		if (s.mode == FROM_INDEX)
-			run_diff_index(&rev, 1);
+			run_diff_index(&rev, DIFF_INDEX_CACHED);
 		else {
 			rev.diffopt.flags.ignore_dirty_submodules = 1;
 			run_diff_files(&rev, 0);

builtin/am.c

@@ -1430,7 +1430,7 @@ static void write_index_patch(const struct am_state *state)
 	rev_info.diffopt.close_file = 1;
 	add_pending_object(&rev_info, &tree->object, "");
 	diff_setup_done(&rev_info.diffopt);
-	run_diff_index(&rev_info, 1);
+	run_diff_index(&rev_info, DIFF_INDEX_CACHED);
 	release_revisions(&rev_info);
 }
 
@@ -1593,7 +1593,7 @@ static int fall_back_threeway(const struct am_state *state, const char *index_pa
 		rev_info.diffopt.filter |= diff_filter_bit('M');
 		add_pending_oid(&rev_info, "HEAD", &our_tree, 0);
 		diff_setup_done(&rev_info.diffopt);
-		run_diff_index(&rev_info, 1);
+		run_diff_index(&rev_info, DIFF_INDEX_CACHED);
 		release_revisions(&rev_info);
 	}
 

builtin/stash.c

@@ -1111,7 +1111,7 @@ static int check_changes_tracked_files(const struct pathspec *ps)
 	add_head_to_pending(&rev);
 	diff_setup_done(&rev.diffopt);
 
-	result = run_diff_index(&rev, 1);
+	result = run_diff_index(&rev, DIFF_INDEX_CACHED);
 	if (diff_result_code(&rev.diffopt, result)) {
 		ret = 1;
 		goto done;

builtin/submodule--helper.c

@@ -1141,7 +1141,7 @@ static int compute_summary_module_list(struct object_id *head_oid,
 	}
 
 	if (diff_cmd == DIFF_INDEX)
-		run_diff_index(&rev, info->cached);
+		run_diff_index(&rev, info->cached ? DIFF_INDEX_CACHED : 0);
 	else
 		run_diff_files(&rev, 0);
 	prepare_submodule_summary(info, &list);

diff-lib.c

@@ -682,7 +682,7 @@ int index_differs_from(struct repository *r,
 			rev.diffopt.flags.ignore_submodules = flags->ignore_submodules;
 	}
 	rev.diffopt.ita_invisible_in_index = ita_invisible_in_index;
-	run_diff_index(&rev, 1);
+	run_diff_index(&rev, DIFF_INDEX_CACHED);
 	has_changes = rev.diffopt.flags.has_changes;
 	release_revisions(&rev);
 	return (has_changes != 0);

wt-status.c

@@ -675,7 +675,7 @@ static void wt_status_collect_changes_index(struct wt_status *s)
 	rev.diffopt.flags.recursive = 1;
 
 	copy_pathspec(&rev.prune_data, &s->pathspec);
-	run_diff_index(&rev, 1);
+	run_diff_index(&rev, DIFF_INDEX_CACHED);
 	release_revisions(&rev);
 }
 
@@ -1156,7 +1156,7 @@ static void wt_longstatus_print_verbose(struct wt_status *s)
 		rev.diffopt.a_prefix = "c/";
 		rev.diffopt.b_prefix = "i/";
 	} /* else use prefix as per user config */
-	run_diff_index(&rev, 1);
+	run_diff_index(&rev, DIFF_INDEX_CACHED);
 	if (s->verbose > 1 &&
 	    wt_status_check_worktree_changes(s, &dirty_submodules)) {
 		status_printf_ln(s, c,
@@ -2614,7 +2614,7 @@ int has_uncommitted_changes(struct repository *r,
 	}
 
 	diff_setup_done(&rev_info.diffopt);
-	result = run_diff_index(&rev_info, 1);
+	result = run_diff_index(&rev_info, DIFF_INDEX_CACHED);
 	result = diff_result_code(&rev_info.diffopt, result);
 	release_revisions(&rev_info);
 	return result;