@[has_globals]
module main

$if windows {
    #include <synchapi.h>

    struct C.builtin__closure__ClosureMutex {
        closure_mtx C.SRWLOCK
    }
} $else {
    #include <pthread.h>

    @[typedef]
    pub struct C.pthread_mutex_t {}

    struct C.builtin__closure__ClosureMutex {
        closure_mtx C.pthread_mutex_t
    }
}

struct C.builtin__closure__Closure {
    ClosureMutex     C.builtin__closure__ClosureMutex
    closure_ptr      voidptr
    closure_get_data voidptr
    closure_cap      int
    v_page_size      int
    free_closure_ptr voidptr
}

__global C.g_closure C.builtin__closure__Closure

fn foo(i int) fn () int {
    return fn [i] () int {
        return i
    }
}

fn test_direct_call_of_returned_closure_reuses_closure_slot() {
    assert foo(-1)() == -1
    start_closure_cap := C.g_closure.closure_cap
    mut sum := 0
    for i in 0 .. 128 {
        sum += foo(i)()
    }
    assert sum == 8128
    assert C.g_closure.closure_cap == start_closure_cap
}