token.QUO: allNumeric,
		token.REM: allInteger,

		token.AND:     allInteger,
		token.OR:      allInteger,
		token.XOR:     allInteger,
		token.AND_NOT: allInteger,

		token.LAND: allBoolean,
		token.LOR:  allBoolean,
	}
}

// If e != nil, it must be the binary expression; it may be nil for non-constant expressions
// (when invoked for an assignment operation where the binary expression is implicit).

		syntax.Div: allNumeric,
		syntax.Rem: allInteger,

		syntax.And:    allInteger,
		syntax.Or:     allInteger,
		syntax.Xor:    allInteger,
		syntax.AndNot: allInteger,

		syntax.AndAnd: allBoolean,
		syntax.OrOr:   allBoolean,
	}
}

// If e != nil, it must be the binary expression; it may be nil for non-constant expressions
// (when invoked for an assignment operation where the binary expression is implicit).

	case *ast.IfStmt:
		check.openScope(s, "if")
		defer check.closeScope()

		check.simpleStmt(s.Init)
		var x operand
		check.expr(nil, &x, s.Cond)
		if x.mode != invalid && !allBoolean(x.typ) {
			check.error(s.Cond, InvalidCond, "non-boolean condition in if statement")
		}
		check.stmt(inner, s.Body)
		// The parser produces a correct AST but if it was modified

	case *syntax.IfStmt:
		check.openScope(s, "if")
		defer check.closeScope()

		check.simpleStmt(s.Init)
		var x operand
		check.expr(nil, &x, s.Cond)
		if x.mode != invalid && !allBoolean(x.typ) {
			check.error(s.Cond, InvalidCond, "non-boolean condition in if statement")
		}
		check.stmt(inner, s.Then)
		// The parser produces a correct AST but if it was modified

// If t is a type parameter the result is true if isX is true
// for all specified types of the type parameter's type set.
// allX is an optimized version of isX(coreType(t)) (which
// is the same as underIs(t, isX)).

func allBoolean(t Type) bool         { return allBasic(t, IsBoolean) }
func allInteger(t Type) bool         { return allBasic(t, IsInteger) }
func allUnsigned(t Type) bool        { return allBasic(t, IsUnsigned) }

// If t is a type parameter the result is true if isX is true
// for all specified types of the type parameter's type set.
// allX is an optimized version of isX(coreType(t)) (which
// is the same as underIs(t, isX)).

func allBoolean(t Type) bool         { return allBasic(t, IsBoolean) }
func allInteger(t Type) bool         { return allBasic(t, IsInteger) }
func allUnsigned(t Type) bool        { return allBasic(t, IsUnsigned) }

	assert(x != nil)
	assert(len(a) == 2)
	if a[0].mode == invalid {
		return
	}
	t0, t1 := a[0].typ, a[1].typ
	assert(isTyped(t0) && isTyped(t1) && (allBoolean(t1) || t1 == universeError))
	if m := check.Types; m != nil {
		for {
			tv := m[x]
			assert(tv.Type != nil) // should have been recorded already
			pos := x.Pos()
			tv.Type = NewTuple(

	assert(x != nil)
	assert(len(a) == 2)
	if a[0].mode == invalid {
		return
	}
	t0, t1 := a[0].typ, a[1].typ
	assert(isTyped(t0) && isTyped(t1) && (allBoolean(t1) || t1 == universeError))
	if m := check.Types; m != nil {
		for {
			tv := m[x]
			assert(tv.Type != nil) // should have been recorded already
			pos := x.Pos()
			tv.Type = NewTuple(