add: use advise function to display hints

Use the advise function in advice.c to display hints to the users, as
it provides a neat and a standard format for hint messages, i.e: the
text is colored in yellow and the line starts by the word "hint:".

Signed-off-by: Heba Waly <[email protected]>

Author: HebaWaly

builtin/add.c

@@ -390,7 +390,7 @@ static int add_files(struct dir_struct *dir, int flags)
 		fprintf(stderr, _(ignore_error));
 		for (i = 0; i < dir->ignored_nr; i++)
 			fprintf(stderr, "%s\n", dir->ignored[i]->name);
-		fprintf(stderr, _("Use -f if you really want to add them.\n"));
+		advise(_("Use -f if you really want to add them.\n"));
 		exit_status = 1;
 	}
 
@@ -480,7 +480,7 @@ int cmd_add(int argc, const char **argv, const char *prefix)
 
 	if (require_pathspec && pathspec.nr == 0) {
 		fprintf(stderr, _("Nothing specified, nothing added.\n"));
-		fprintf(stderr, _("Maybe you wanted to say 'git add .'?\n"));
+		advise( _("Maybe you wanted to say 'git add .'?\n"));
 		return 0;
 	}
 

t/t3700-add.sh

@@ -326,7 +326,7 @@ test_expect_success 'git add --dry-run of an existing file output' "
 cat >expect.err <<\EOF
 The following paths are ignored by one of your .gitignore files:
 ignored-file
-Use -f if you really want to add them.
+hint: Use -f if you really want to add them.
 EOF
 cat >expect.out <<\EOF
 add 'track-this'