fixes #5519

tests/iter/tclosureiters.nim

@@ -103,3 +103,39 @@ proc unusedB =
   var count = 0
   for line in lineIter2("temp10.nim"):
     count += 1
+
+# bug #5519
+import os, algorithm
+
+iterator filesIt(path: string): auto {.closure.} =
+  var files = newSeq[string]()
+  var dirs = newSeq[string]()
+  for k, p in os.walkDir(path):
+    let (_, n, e) = p.splitFile
+    if e != "":
+      continue
+    case k
+    of pcFile, pcLinkToFile:
+      files.add(n)
+    else:
+      dirs.add(n)
+  files.sort(system.cmp)
+  dirs.sort(system.cmp)
+  for f in files:
+    yield f
+
+  for d in dirs:
+    files = newSeq[string]()
+    for k, p in os.walkDir(path / d):
+      let (_, n, e) = p.splitFile
+      if e != "":
+        continue
+      case k
+      of pcFile, pcLinkToFile:
+        files.add(n)
+      else:
+        discard
+    files.sort(system.cmp)
+    let prefix = path.splitPath[1]
+    for f in files:
+      yield prefix / f