`Make[T]` function, which produces a reference to a canonical copy of
the value in the form of a `Handle[T]`.
Two `Handle[T]` are equal if and only if the values used to produce the
handles are equal, allowing programs to deduplicate values and reduce
their memory footprint.
Comparing two `Handle[T]` values is efficient, reducing down to a simple

	f := strings.Join(w.scope, ", ") + ", " + fmt.Sprintf(format, args...)
	if strings.Contains(f, "\n") {
		panic("feature contains newlines: " + f)
	}

	if _, dup := w.features[f]; dup {
		panic("duplicate feature inserted: " + f)
	}
	w.features[f] = true

	if verbose {
		log.Printf("feature: %s", f)
	}
}

func needApproval(filename string) bool {
	name := filepath.Base(filename)

Don't profile the marked function.  This flag is deprecated.
</li>
<li>
<code>DUPOK</code> = 2
<br>
It is legal to have multiple instances of this symbol in a single binary.
The linker will choose one of the duplicates to use.
</li>
<li>
<code>NOSPLIT</code> = 4
<br>
(For <code>TEXT</code> items.)
Don't insert the preamble to check if the stack must be split.

pkg syscall (windows-386), const DNS_TYPE_WINSR = 65282
pkg syscall (windows-386), const DNS_TYPE_WKS = 11
pkg syscall (windows-386), const DNS_TYPE_X25 = 19
pkg syscall (windows-386), const DUPLICATE_CLOSE_SOURCE = 1
pkg syscall (windows-386), const DUPLICATE_SAME_ACCESS = 2
pkg syscall (windows-386), const E2BIG = 536870912
pkg syscall (windows-386), const EACCES = 536870913
pkg syscall (windows-386), const EADDRINUSE = 536870914

			hi := lo
			if p.peek() == '-' {
				p.next()
				hi = p.registerNumber(p.next().String())
			}
			if hi < lo {
				lo, hi = hi, lo
			}
			// Check there are no duplicates in the register list.
			for i := 0; lo <= hi && i < maxReg; i++ {
				if bits&(1<<lo) != 0 {
					p.errorf("register R%d already in list", lo)
				}
				bits |= 1 << lo
				lo++
			}
		default: