fixes #5933

tests/js/tseqops.nim

@@ -0,0 +1,51 @@
+discard """
+  output: '''(x: 0, y: 0)
+(x: 5, y: 0)
+@[(x: 2, y: 4), (x: 4, y: 5), (x: 4, y: 5)]
+@[(a: 3, b: 3), (a: 1, b: 1), (a: 2, b: 2)]
+'''
+"""
+
+# bug #4139
+
+type
+  TestO = object
+    x, y: int
+
+proc onLoad() =
+  var test: seq[TestO] = @[]
+  var foo = TestO(x: 0, y: 0)
+  test.add(foo)
+  foo.x = 5
+  echo(test[0])
+  echo foo
+
+onLoad()
+
+# 'setLen' bug (part of bug #5933)
+type MyObj = object
+  x: cstring
+  y: int
+
+proc foo(x: var seq[MyObj]) =
+  let L = x.len
+  x.setLen L + 1
+  x[L] = x[1]
+
+var s = @[MyObj(x: "2", y: 4), MyObj(x: "4", y: 5)]
+foo(s)
+echo s
+
+# bug  #5933
+import sequtils
+
+type
+  Test = object
+    a: cstring
+    b: int
+
+var test = @[Test(a: "1", b: 1), Test(a: "2", b: 2)]
+
+test.insert(@[Test(a: "3", b: 3)], 0)
+
+echo test