src/Pure/General/file.ML

 fun tmp_path path = Path.variable "ISABELLE_TMP" + Path.base path;
 
 
 (* directory entries *)
 
-val exists = can OS.FileSys.modTime o platform_path;
+val exists = can OS.FileSys.fileId o platform_path;
 
 val rm = OS.FileSys.remove o platform_path;
 
 fun test_dir path = the_default false (try OS.FileSys.isDir (platform_path path));
 fun is_dir path = exists path andalso test_dir path;