Forced to forward declare when overloading = and =sink

[mratsim]

None of the following compiles

type
  Foo = object
  Bar = object
    foo: Foo

proc `=`*(dest: var Foo, src: Foo) =
  echo "hello World!"
  system.`=`(dest, src)

proc `=sink`*(dst: var Foo, src: Foo) {.inline.} =
  system.`=sink`(dst, src)

proc initFoo(): Foo =
  discard

proc initBar(foo: sink Foo): Bar =
  echo "hi"
  result.foo = foo
  echo "ho"

proc main =
  let x = initFoo()
  echo "ha"
  let y = initBar(x)

main()

Error: cannot bind another '=sink' to: Foo; previous declaration was constructed here implicitly: .../Nim/weave/build/dest.nim(8, 13)

type
  Foo = object
  Bar = object
    foo: Foo

proc `=`*(dest: var Foo, src: Foo) =
  echo "hello World!"
  system.`=`(dest, src)

proc `=sink`*(dst: var Foo, src: Foo) {.inline.} =
  system.`=sink`(dst, src)

proc initFoo(): Foo =
  discard

proc initBar(foo: sink Foo): Bar =
  echo "hi"
  result.foo = foo
  echo "ho"

proc main =
  let x = initFoo()
  echo "ha"
  let y = initBar(x)

main()

Error: cannot bind another '=' to: Foo; previous declaration was constructed here implicitly: .../nim-#devel/lib/system.nim(471, 16)

The workaround is to forward declare one of them.