Thank you, @oniboni for this issue and discussion!

A couple of things comes to mind from this:

• We should have a section in the documentation about these "tricks" (accessing a field in a parameter struct is another such case)
• We should think about "early" and "late" values in the constraints, perhaps use that as terms in the documentation
• Perhaps return_by_value() should be named differently, or perhaps even removed

from cgreen.

Solution

as proposed #297 (comment)

ssize_t send_data(void *data, size_t data_len) {
  return *(*ssize_t)mock(data, data_len);
}

// [...]
Expect(SUT, some_test_where_data_needs_to_be_sent) {
  // Prepare
  ssize_t data_len_capture = 0;

  // Expect
  expect(send_data, will_set_contents_of_parameter(data_len, data_len_capture, sizeof(data_len_capture)),
         will_return(&data_len_capture));

  // Act
  SUT_function_call();

  // Assert
}

from cgreen.