fixes #11510

tests/destructor/tmisc_destructors.nim

@@ -0,0 +1,41 @@
+discard """
+  output: '''@[0]
+@[1]
+@[2]
+@[3]'''
+  joinable: false
+"""
+
+# bug #6434
+
+type
+  Foo* = object
+    boo: int
+
+var sink_counter = 0
+var assign_counter = 0
+
+proc `=sink`(dest: var Foo, src: Foo) =
+  sink_counter.inc
+
+proc `=`(dest: var Foo, src: Foo) =
+  assign_counter.inc
+
+proc test(): auto =
+  var a,b : Foo
+  return (a, b, Foo(boo: 5))
+
+var (a, b, _) = test()
+
+doAssert assign_counter == 0
+doAssert sink_counter == 12 # + 3 because of the conservative tuple unpacking transformation
+
+# bug #11510
+proc main =
+  for i in 0 ..< 4:
+    var buffer: seq[int] # = @[] # uncomment to make it work
+    # var buffer: string # also this is broken
+    buffer.add i
+    echo buffer
+
+main()