// Types to represent untyped string and boolean constants.
	UntypedString = newType(TSTRING)
	UntypedBool   = newType(TBOOL)

	// Types to represent untyped numeric constants.
	UntypedInt     = newType(TIDEAL)
	UntypedRune    = newType(TIDEAL)
	UntypedFloat   = newType(TIDEAL)
	UntypedComplex = newType(TIDEAL)
)

// UntypedTypes maps from a constant.Kind to its untyped Type
// representation.
var UntypedTypes = [...]*Type{

		// the value nil.
		switch x.typ.(*Basic).kind {
		case UntypedBool:
			if !isBoolean(target) {
				return nil, nil, InvalidUntypedConversion
			}
		case UntypedInt, UntypedRune, UntypedFloat, UntypedComplex:
			if !isNumeric(target) {
				return nil, nil, InvalidUntypedConversion
			}
		case UntypedString:
			// Non-constant untyped string values are not permitted by the spec and

		// the value nil.
		switch x.typ.(*Basic).kind {
		case UntypedBool:
			if !isBoolean(target) {
				return nil, nil, InvalidUntypedConversion
			}
		case UntypedInt, UntypedRune, UntypedFloat, UntypedComplex:
			if !isNumeric(target) {
				return nil, nil, InvalidUntypedConversion
			}
		case UntypedString:
			// Non-constant untyped string values are not permitted by the spec and