func (check *Checker) unary(x *operand, op token.Token) {
switch op {
case token.AND:
// spec: "As an exception to the addressability
// requirement x may also be a composite literal."
if _, ok := unparen(x.expr).(*ast.CompositeLit); !ok && x.mode != variable {
check.invalidOp(x.pos(), "cannot take address of %s", x)
x.mode = invalid
return
}
x.mode = value
x.typ = &Pointer{base: x.typ}
return
case token.ARROW:
typ, ok := x.typ.Underlying().(*Chan)
if !ok {
check.invalidOp(x.pos(), "cannot receive from non-channel %s", x)
x.mode = invalid
return
}
if typ.dir == SendOnly {
check.invalidOp(x.pos(), "cannot receive from send-only channel %s", x)
x.mode = invalid
return
}
x.mode = commaok
x.typ = typ.elem
check.hasCallOrRecv = true
return
}
if !check.op(unaryOpPredicates, x, op) {
x.mode = invalid
return
}
if x.mode == constant {
typ := x.typ.Underlying().(*Basic)
size := -1
if isUnsigned(typ) {
size = int(check.conf.sizeof(typ))
}
x.val = exact.UnaryOp(op, x.val, size)
// Typed constants must be representable in
// their type after each constant operation.
if isTyped(typ) {
check.representable(x, typ)
}
return
}
x.mode = value
// x.typ remains unchanged
}
func (p *importer) fraction() exact.Value {
sign := p.int()
if sign == 0 {
return exact.MakeInt64(0)
}
x := exact.BinaryOp(p.ufloat(), token.QUO, p.ufloat())
if sign < 0 {
x = exact.UnaryOp(token.SUB, x, 0)
}
return x
}