New policy: no readmePrefix in dirs without Holmakefile

Author: myreen

compiler/benchmarks/readmePrefix renamed to compiler/benchmarks/README.md

@@ -310,8 +310,14 @@ fun run_full_check () = let
     if p = path then "." else remove_prefix (path ^ "/") p
   fun check_dir p =
     case read_all_lines (p ^ "/Holmakefile") of
-      NONE => ()
-    | SOME lines =>
+      NONE => (* case: Holmake file does not exist *)
+        let
+          val _ = assert_for_lines_of (p ^ "/" ^ PREFIX_FILENAME)
+                    (not o Option.isSome)
+                    (fn s => "File not allowed to exist: " ^ s ^ "\n" ^
+                             "Such files are only allowed in directories with a Holmakefile.\nFix: rename the file to " ^ OUTPUT_FILENAME)
+        in () end
+    | SOME lines => (* case: Holmake file exists *)
         let
           val _ = assert_for_lines_of (p ^ "/" ^ PREFIX_FILENAME)
                     Option.isSome (fn s => "Missing file: " ^ s)