src/Pure/Tools/scala_project.scala

--- a/src/Pure/Tools/scala_project.scala	Sat Feb 27 17:33:40 2021 +0100
+++ b/src/Pure/Tools/scala_project.scala	Sat Feb 27 18:04:29 2021 +0100
@@ -129,7 +129,8 @@
         }).getOrElse(error("Unknown directory prefix for " + quote(file)))
 
       Isabelle_System.make_directory(target)
-      if (symlinks) File.link(path, target) else File.copy(path, target)
+      if (symlinks) Isabelle_System.symlink(path, target)
+      else Isabelle_System.copy_file(path, target)
     }
 
     val jars =