func badFormatAt(info *types.Info, e ast.Expr) int {
	tv, ok := info.Types[e]
	if !ok { // no type info, assume good
		return -1
	}

	t, ok := tv.Type.(*types.Basic) // sic, no unalias
	if !ok || t.Info()&types.IsString == 0 {
		return -1
	}

	if tv.Value == nil {
		return -1
	}

	return strings.Index(constant.StringVal(tv.Value), badFormat)

func kindOf(value any) reflect.Kind {
	if value == nil {
		return reflect.Invalid
	}
	return reflect.TypeOf(value).Kind()
}

// IsString reports whether value is a string type.
func IsString(value any) bool {
	return kindOf(value) == reflect.String
}

// IsPtr reports whether value is a ptr type.
func IsPtr(value any) bool {
	return kindOf(value) == reflect.Ptr
}

// a string, the result is of type (possibly untyped) string.
func coreString(t Type) Type {
	t = Unalias(t)
	tpar, _ := t.(*TypeParam)
	if tpar == nil {
		return under(t) // string or untyped string
	}

	var su Type
	hasString := false
	if tpar.underIs(func(u Type) bool {
		if u == nil {
			return false
		}
		if isString(u) {
			u = NewSlice(universeByte)

func NewInt(pos src.XPos, v int64) Node {
	return NewBasicLit(pos, types.UntypedInt, constant.MakeInt64(v))
}

// NewString returns an OLITERAL representing s as an untyped string.
func NewString(pos src.XPos, s string) Node {
	return NewBasicLit(pos, types.UntypedString, constant.MakeString(s))
}

// NewUintptr returns an OLITERAL representing v as a uintptr.
func NewUintptr(pos src.XPos, v int64) Node {

		// StdSizes.Alignof won't be called for them.
		assert(!isTypeParam(T))
		return s.WordSize
	case *Basic:
		// Strings are like slices and interfaces.
		if t.Info()&IsString != 0 {
			return s.WordSize
		}
	case *TypeParam, *Union:
		panic("unreachable")
	}
	a := s.Sizeof(T) // may be 0 or negative
	// spec: "For a variable x of any type: unsafe.Alignof(x) is at least 1."
	if a < 1 {

		// StdSizes.Alignof won't be called for them.
		assert(!isTypeParam(T))
		return s.WordSize
	case *Basic:
		// Strings are like slices and interfaces.
		if t.Info()&IsString != 0 {
			return s.WordSize
		}
	case *TypeParam, *Union:
		panic("unreachable")
	}
	a := s.Sizeof(T) // may be 0 or negative
	// spec: "For a variable x of any type: unsafe.Alignof(x) is at least 1."
	if a < 1 {

				*rounded = constant.BinaryOp(re, token.ADD, constant.MakeImag(im))
				return true
			}
		case UntypedComplex:
			return true
		default:
			panic("unreachable")
		}

	case isString(typ):
		return x.Kind() == constant.String

	case isBoolean(typ):
		return x.Kind() == constant.Bool
	}

	return false
}

func fitsFloat32(x constant.Value) bool {
	f32, _ := constant.Float32Val(x)

				*rounded = constant.BinaryOp(re, token.ADD, constant.MakeImag(im))
				return true
			}
		case UntypedComplex:
			return true
		default:
			panic("unreachable")
		}

	case isString(typ):
		return x.Kind() == constant.String

	case isBoolean(typ):
		return x.Kind() == constant.Bool
	}

	return false
}

func fitsFloat32(x constant.Value) bool {
	f32, _ := constant.Float32Val(x)

		// StdSizes.Alignof won't be called for them.
		assert(!isTypeParam(T))
		return s.WordSize
	case *Basic:
		// Strings are like slices and interfaces.
		if t.Info()&IsString != 0 {
			return s.WordSize
		}
	case *TypeParam, *Union:
		panic("unreachable")
	}
	a := s.Sizeof(T) // may be 0 or negative
	// spec: "For a variable x of any type: unsafe.Alignof(x) is at least 1."

		// StdSizes.Alignof won't be called for them.
		assert(!isTypeParam(T))
		return s.WordSize
	case *Basic:
		// Strings are like slices and interfaces.
		if t.Info()&IsString != 0 {
			return s.WordSize
		}
	case *TypeParam, *Union:
		panic("unreachable")
	}
	a := s.Sizeof(T) // may be 0 or negative
	// spec: "For a variable x of any type: unsafe.Alignof(x) is at least 1."