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diff --git a/tests/ccgbugs/twrong_tupleconv.nim b/tests/ccgbugs/twrong_tupleconv.nim
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+++ b/tests/ccgbugs/twrong_tupleconv.nim
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+discard """
+  targets: "c cpp"
+  matrix: "--gc:refc; --gc:arc"
+"""
+
+# bug #1833
+iterator myitems*[T](a: var seq[T]): var T {.inline.} =
+  ## iterates over each item of `a` so that you can modify the yielded value.
+  var i = 0
+  let L = len(a)
+  while i < L:
+    yield a[i]
+    inc(i)
+    doAssert(len(a) == L, "the length of the seq changed while iterating over it")
+
+# Works fine
+var xs = @[1,2,3]
+for x in myitems(xs):
+  inc x
+
+# Tuples don't work
+var ys = @[(1,"a"),(2,"b"),(3,"c")]
+for y in myitems(ys):
+  inc y[0]
+
+# bug #16331
+type T1 = tuple[a, b: int]
+
+proc p(b: bool): string =
+  var x: T1 = (10, 20)
+  x = if b: (x.b, x.a) else: (-x.b, -x.a)
+  $x
+
+assert p(false) == "(a: -20, b: -10)"
+assert p(true) == "(a: 20, b: 10)"