*ast.MapType, *ast.ChanType:

		return true
	}
	return false
}

// isUnsafeData reports whether the expression is unsafe.StringData
// or unsafe.SliceData. We can ignore these when checking for pointers
// because they don't change whether or not their argument contains
// any Go pointers. If onlyStringData is true we only check for StringData.

<p>
The following built-in functions are not permitted in statement context:
</p>

<pre>
append cap complex imag len make new real
unsafe.Add unsafe.Alignof unsafe.Offsetof unsafe.Sizeof unsafe.Slice unsafe.SliceData unsafe.String unsafe.StringData
</pre>

<pre>
h(x+y)
f.Close()
&lt;-ch
(&lt;-ch)
len("foo")  // illegal if len is the built-in function
</pre>