Ppx_let_expander.LocalityControls the locality of the closure generated by the ppx, and that closure's return value.
{allocate_function_on_stack = false; return_value_in_exclave = false}{allocate_function_on_stack = true; return_value_in_exclave = false}{allocate_function_on_stack = false; return_value_in_exclave = true}{allocate_function_on_stack = true; return_value_in_exclave = true}val global : tval all : t list