[bugfix] system.nim: make pop work with --newruntime

tests/destructor/tbintree2.nim

@@ -0,0 +1,103 @@
+discard """
+  cmd: '''nim c --newruntime $file'''
+  output: '''0
+3 3  alloc/dealloc pairs: 0'''
+"""
+
+import core / allocators
+import system / ansi_c
+
+import random
+
+type Node = ref object
+  x, y: int32
+  left, right: owned Node
+
+proc newNode(x: int32): owned Node =
+  result = Node(x: x, y: rand(high int32).int32)
+
+proc merge(lower, greater: owned Node): owned Node =
+  if lower.isNil:
+    result = greater
+  elif greater.isNil:
+    result = lower
+  elif lower.y < greater.y:
+    lower.right = merge(lower.right, greater)
+    result = lower
+  else:
+    greater.left = merge(lower, greater.left)
+    result = greater
+
+proc splitBinary(orig: owned Node, value: int32): (owned Node, owned Node) =
+  if orig.isNil:
+    result = (nil, nil)
+  elif orig.x < value:
+    let splitPair = splitBinary(orig.right, value)
+    orig.right = splitPair[0]
+    result = (orig, splitPair[1])
+  else:
+    let splitPair = splitBinary(orig.left, value)
+    orig.left = splitPair[1]
+    result = (splitPair[0], orig)
+
+proc merge3(lower, equal, greater: owned Node): owned Node =
+  merge(merge(lower, equal), greater)
+
+proc split(orig: owned Node, value: int32): tuple[lower, equal, greater: owned Node] =
+  let
+    (lower, equalGreater) = splitBinary(orig, value)
+    (equal, greater) = splitBinary(equalGreater, value + 1)
+  result = (lower, equal, greater)
+
+type Tree = object
+  root: owned Node
+
+proc `=destroy`(t: var Tree) {.nodestroy.} =
+  var s: seq[owned Node] = @[t.root]
+  while s.len > 0:
+    let x = s.pop
+    if x.left != nil: s.add(x.left)
+    if x.right != nil: s.add(x.right)
+    dispose(x)
+  `=destroy`(s)
+
+proc hasValue(self: var Tree, x: int32): bool =
+  let splited = split(move self.root, x)
+  result = not splited.equal.isNil
+  self.root = merge3(splited.lower, splited.equal, splited.greater)
+
+proc insert(self: var Tree, x: int32) =
+  var splited = split(move self.root, x)
+  if splited.equal.isNil:
+    splited.equal = newNode(x)
+  self.root = merge3(splited.lower, splited.equal, splited.greater)
+
+proc erase(self: var Tree, x: int32) =
+  let splited = split(move self.root, x)
+  self.root = merge(splited.lower, splited.greater)
+
+proc main() =
+  var
+    tree = Tree()
+    cur = 5'i32
+    res = 0
+
+  for i in 1 ..< 10:
+    let a = i mod 3
+    cur = (cur * 57 + 43) mod 10007
+    case a:
+    of 0:
+      tree.insert(cur)
+    of 1:
+      tree.erase(cur)
+    of 2:
+      if tree.hasValue(cur):
+        res += 1
+    else:
+      discard
+  echo res
+
+main()
+
+let (a, d) = allocCounters()
+discard cprintf("%ld %ld  alloc/dealloc pairs: %ld\n", a, d, system.allocs)