go 1.11.1 source code is below:

Generally speaking, make chan just pay attention to the presence or absence 
of buf.

When I saw the source code of make chan,  I can understand case 1: chan buf 
is 0, but can't understand case 2 & default.

Who knows this principle?

Thanks!

var c *hchan
    switch {
    case size == 0 || elem.size == 0:
        // Queue or element size is zero.
        c = (*hchan)(mallocgc(hchanSize, nil, true))
        // Race detector uses this location for synchronization.
        c.buf = c.raceaddr()
    case elem.kind&kindNoPointers != 0:
        // Elements do not contain pointers.
        // Allocate hchan and buf in one call.
        c = (*hchan)(mallocgc(hchanSize+uintptr(size)*elem.size, nil, true))
        c.buf = add(unsafe.Pointer(c), hchanSize)
    default:
        // Elements contain pointers.
        c = new(hchan)
        c.buf = mallocgc(uintptr(size)*elem.size, elem, true)
    }

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