remove $ for ptr/ref, prefer using string over array of char

lib/system.nim

@@ -1872,26 +1872,20 @@ proc `$` *[Enum: enum](x: Enum): string {.magic: "EnumToStr", noSideEffect.}
   ## a ``$`` operator for a concrete enumeration is provided, this is
   ## used instead. (In other words: *Overwriting* is possible.)
 
-proc `$`*[T: ref](arg: T): string =
-  ## The stringify operator to handle the nil value of all ref types.
-  ## Then it forwards to stringify operator of the underlying (value) type.
-  if arg.isNil:
-    "nil"
-  else:
-    "ref " & $arg[]
-
-proc `$`*[T: ptr](arg: T): string =
-  ## The stringify operator to handle the nil value of all ptr types.
-  ## Then it forwards to stringify operator of the underlying (value) type.
-  if arg.isNil:
-    "nil"
-  else:
-    "ptr " & $arg[]
-
-proc newString*[N](data: array[N, char]): string =
+proc newString*[N](data: array[N, char]): string {.noSideEffect.} =
   ## Construct a string from an array of characters. The `data` is
   ## expected to be a null terminated string as it is often used in C.
-  $(cast[cstring](data[0].unsafeAddr))
+  when nimvm:
+    # cannot cast on the vm
+    # not recommended to use this procedure on the vm at all, but at least it doesn't fail.
+    result = ""
+    for c in data:
+      if c == '\0':
+        return
+      else:
+        result.add c
+  else:
+    result = $(cast[cstring](data[0].unsafeAddr))
 
 # undocumented:
 proc getRefcount*[T](x: ref T): int {.importc: "getRefcount", noSideEffect.}