borrows of parameters below byref threshold ends up leasing the copied parameter

[alaviss]

Example

{.experimental: "views".}
type
  Mint = object
    data: int

  Option = object
    value: lent Mint

proc `=copy`(dst: var Mint, src: Mint) {.error.}

proc some(x: Mint): Option =
  Option(value: x)

proc main() =
  var x = Mint(data: 10)
  let optlent = some(x)

main()

Actual Output

C Code for some(x):

N_LIB_PRIVATE N_NIMCALL(_L6Option_2_M4test, some__test_8)(_L4Mint_1_M4test x) {
	_L6Option_2_M4test result;
	_L4Mint_1_M4test* _2;
	nimfr_("some", "/tmp/test.nim");
	nimln_(12, "/tmp/test.nim");
	_2 = (&x);
	nimZeroMem((void*)(&result), sizeof(_L6Option_2_M4test));
	result.value = _2;
	popFrame();
	return result;
}

Expected Output

The x parameter should be a pointer, not a stack copy.

Additional information

• If Mint is tagged with {.byref.}, the generated code is correct.