// expr = term | term ('+' | '-' | '|' | '^') term.
func (p *Parser) expr() uint64 {
	value := p.term()
	for {
		switch p.peek() {
		case '+':
			p.next()
			value += p.term()
		case '-':
			p.next()
			value -= p.term()
		case '|':
			p.next()
			value |= p.term()
		case '^':
			p.next()
			value ^= p.term()
		default:
			return value
		}

	case s.terms.isEmpty():
		w.string(s.terms.String())
	default:
		var termHashes []string
		for _, term := range s.terms {
			// terms are not canonically sorted, so we sort their hashes instead.
			var buf bytes.Buffer
			if term.tilde {
				buf.WriteByte('~')
			}
			newTypeHasher(&buf, w.ctxt).typ(term.typ)
			termHashes = append(termHashes, buf.String())
		}
		sort.Strings(termHashes)
		if !first {

	tmap := map[string]*Term{
		"int":     NewTerm(false, Typ[Int]),
		"~int":    NewTerm(true, Typ[Int]),
		"string":  NewTerm(false, Typ[String]),
		"~string": NewTerm(true, Typ[String]),
		"myInt":   NewTerm(false, myInt),
	}
	makeUnion := func(s string) *Union {
		parts := strings.Split(s, "|")
		var terms []*Term
		for _, p := range parts {
			term := tmap[p]
			if term == nil {

// What remains is to choose e.
// Let m = 2^e/c + delta, 0 <= delta < 1
//   ⎣x * (2^e/c + delta) / 2^e⎦
//   ⎣x / c + x * delta / 2^e⎦
// We must have x * delta / 2^e < 1/c so that this
// additional term never rounds differently than ⎣x / c⎦ does.
// Rearranging,
//   2^e > x * delta * c
// x can be at most 2^n-1 and delta can be at most 1.
// So it is sufficient to have 2^e >= 2^n*c.

			// labeled for loop
			lab = s.label(sym)
			lab.continueTarget = bIncr
			lab.breakTarget = bEnd
		}

		// generate body
		s.startBlock(bBody)
		s.stmtList(n.Body)

		// tear down continue/break
		s.continueTo = prevContinue
		s.breakTo = prevBreak
		if lab != nil {
			lab.continueTarget = nil
			lab.breakTarget = nil
		}

		// done with body, goto incr

//
// By default, the go command may download modules from https://proxy.golang.org.
// It may authenticate modules using the checksum database at
// https://sum.golang.org. Both services are operated by the Go team at Google.
// The privacy policies for these services are available at
// https://proxy.golang.org/privacy and https://sum.golang.org/privacy,
// respectively.
//

			}
			return false
		}
		return checkComparability()
	}

	// Otherwise, V's type must be included in the iface type set.
	var alt Type
	if Ti.typeSet().is(func(t *term) bool {
		if !t.includes(V) {
			// If V ∉ t.typ but V ∈ ~t.typ then remember this type
			// so we can suggest it as an alternative in the error
			// message.

			return err
		}
	}

	return nil
}

// PrintEnv prints the environment variables to w.
func PrintEnv(w io.Writer, env []cfg.EnvVar, onlyChanged bool) {
	for _, e := range env {
		if e.Name != "TERM" {
			if runtime.GOOS != "plan9" && bytes.Contains([]byte(e.Value), []byte{0}) {
				base.Fatalf("go: internal error: encountered null byte in environment variable %s on non-plan9 platform", e.Name)
			}

		return nil
	}
	if pos >= c.last() {
		return fmt.Errorf("pos not decreasing")
	}
	c.s[len(c.s)-1].st = pos + 1
	// terminate lifetime
	c.setLast(-1)
	if debugtrace {
		fmt.Fprintf(os.Stderr, "=-= term lifetime at pos=%d\n", pos)
	}
	return nil
}

// check examines the intervals in "is" to try to find internal
// inconsistencies or problems.
func check(is Intervals) error {
	for i := 0; i < len(is); i++ {

// allBasic(t, info) is an optimized version of isBasic(coreType(t), info).
func allBasic(t Type, info BasicInfo) bool {
	if tpar, _ := Unalias(t).(*TypeParam); tpar != nil {
		return tpar.is(func(t *term) bool { return t != nil && isBasic(t.typ, info) })
	}
	return isBasic(t, info)
}

// hasName reports whether t has a name. This includes
// predeclared types, defined types, and type parameters.