// basic type.
func (check *Checker) representable(x *operand, typ *Basic) {
	v, code := check.representation(x, typ)
	if code != 0 {
		check.invalidConversion(code, x, typ)
		x.mode = invalid
		return
	}
	assert(v != nil)
	x.val = v
}

// representation returns the representation of the constant operand x as the
// basic type typ.
//

// basic type.
func (check *Checker) representable(x *operand, typ *Basic) {
	v, code := check.representation(x, typ)
	if code != 0 {
		check.invalidConversion(code, x, typ)
		x.mode = invalid
		return
	}
	assert(v != nil)
	x.val = v
}

// representation returns the representation of the constant operand x as the
// basic type typ.
//

	case x.convertibleTo(check, T, &cause):
		// non-constant conversion
		ok = true
		x.mode = value
	}

	if !ok {
		if cause != "" {
			check.errorf(x, InvalidConversion, "cannot convert %s to type %s: %s", x, T, cause)
		} else {
			check.errorf(x, InvalidConversion, "cannot convert %s to type %s", x, T)
		}
		x.mode = invalid
		return
	}

	// The conversion argument types are final. For untyped values the

	case x.convertibleTo(check, T, &cause):
		// non-constant conversion
		ok = true
		x.mode = value
	}

	if !ok {
		if cause != "" {
			check.errorf(x, InvalidConversion, "cannot convert %s to type %s: %s", x, T, cause)
		} else {
			check.errorf(x, InvalidConversion, "cannot convert %s to type %s", x, T)
		}
		x.mode = invalid
		return
	}

	// The conversion argument types are final. For untyped values the

	_ = x[InvalidImag-89]
	_ = x[InvalidLen-90]
	_ = x[SwappedMakeArgs-91]
	_ = x[InvalidMake-92]
	_ = x[InvalidReal-93]
	_ = x[InvalidAssert-94]
	_ = x[ImpossibleAssert-95]
	_ = x[InvalidConversion-96]
	_ = x[InvalidUntypedConversion-97]
	_ = x[BadOffsetofSyntax-98]
	_ = x[InvalidOffsetof-99]
	_ = x[UnusedExpr-100]
	_ = x[UnusedVar-101]
	_ = x[MissingReturn-102]
	_ = x[WrongResultCount-103]

	_ = x[InvalidDelete-88]
	_ = x[InvalidImag-89]
	_ = x[InvalidLen-90]
	_ = x[SwappedMakeArgs-91]
	_ = x[InvalidMake-92]
	_ = x[InvalidReal-93]
	_ = x[InvalidAssert-94]
	_ = x[ImpossibleAssert-95]
	_ = x[InvalidConversion-96]
	_ = x[InvalidUntypedConversion-97]
	_ = x[BadOffsetofSyntax-98]
	_ = x[InvalidOffsetof-99]
	_ = x[UnusedExpr-100]
	_ = x[UnusedVar-101]
	_ = x[MissingReturn-102]
	_ = x[WrongResultCount-103]

	//  var _ = x.(T)
	ImpossibleAssert

	/* exprs > conversion */

	// InvalidConversion occurs when the argument type cannot be converted to the
	// target.
	//
	// See https://golang.org/ref/spec#Conversions for the rules of
	// convertibility.
	//
	// Example:
	//  var x float64
	//  var _ = string(x)
	InvalidConversion

	// InvalidUntypedConversion occurs when an there is no valid implicit

	//
	//  var x I
	//  var _ = x.(T)
	ImpossibleAssert

	// InvalidConversion occurs when the argument type cannot be converted to the
	// target.
	//
	// See https://golang.org/ref/spec#Conversions for the rules of
	// convertibility.
	//
	// Example:
	//  var x float64
	//  var _ = string(x)
	InvalidConversion

	// InvalidUntypedConversion occurs when there is no valid implicit

		return n
	}
	op, why := convertOp(n.X.Op() == ir.OLITERAL, t, n.Type())
	if op == ir.OXXX {
		// Due to //go:nointerface, we may be stricter than types2 here (#63333).
		base.ErrorfAt(n.Pos(), errors.InvalidConversion, "cannot convert %L to type %v%s", n.X, n.Type(), why)
		n.SetType(nil)
		return n
	}

	n.SetOp(op)
	switch n.Op() {
	case ir.OCONVNOP:
		if t.Kind() == n.Type().Kind() {
			switch t.Kind() {