The [SliceAt(typ Type, p unsafe.Pointer, len int)] function
returns a Value representing a slice whose underlying array starts

pkg os, func CopyFS(string, fs.FS) error #62484
pkg path/filepath, func Localize(string) (string, error) #57151
pkg reflect, func SliceAt(Type, unsafe.Pointer, int) Value #61308
pkg reflect, method (Value) Seq() iter.Seq[Value] #66056
pkg reflect, method (Value) Seq2() iter.Seq2[Value, Value] #66056
pkg reflect, type Type interface, CanSeq() bool #66056

	}

	typ = TypeOf(0)
	if !SliceAt(typ, unsafe.Pointer((*int)(nil)), 0).IsNil() {
		t.Fatal("nil pointer with zero length must return nil")
	}

	// nil pointer with positive length panics
	shouldPanic("", func() { _ = SliceAt(typ, unsafe.Pointer((*int)(nil)), 1) })

	// negative length
	var neg int = -1
	shouldPanic("", func() { _ = SliceAt(TypeOf(byte(0)), unsafe.Pointer(&p[0]), neg) })

	return Value{&typ.(*rtype).t, unsafe.Pointer(&s), flagIndir | flag(Slice)}
}

// SliceAt returns a [Value] representing a slice whose underlying
// data starts at p, with length and capacity equal to n.
//
// This is like [unsafe.Slice].
func SliceAt(typ Type, p unsafe.Pointer, n int) Value {
	unsafeslice(typ.common(), p, n)
	s := unsafeheader.Slice{Data: p, Len: n, Cap: n}

	case a.pointerT == nil:
		return errors.New(a.name + " missing pointerT")
	case a.arrayT == nil:
		return errors.New(a.name + " missing arrayT")
	case a.sliceT == nil:
		return errors.New(a.name + " missing sliceT")
	case a.mapT == nil:
		return errors.New(a.name + " missing mapT")
	case a.mapPointerKeyT == nil:
		return errors.New(a.name + " missing mapPointerKeyT")
	case a.chanT == nil:

		fmt.Fprintf(os.Stderr, "%skey id=%d\n", indent+1, wire.MapT.Key)
		fmt.Fprintf(os.Stderr, "%selem id=%d\n", indent+1, wire.MapT.Elem)
	case wire.SliceT != nil:
		deb.printCommonType(indent, "slice", &wire.SliceT.CommonType)
		fmt.Fprintf(os.Stderr, "%selem id=%d\n", indent+1, wire.SliceT.Elem)
	case wire.StructT != nil:
		deb.printCommonType(indent, "struct", &wire.StructT.CommonType)
		for i, field := range wire.StructT.Field {

	const unknown = "unknown type"
	if w == nil {
		return unknown
	}
	switch {
	case w.ArrayT != nil:
		return w.ArrayT.Name
	case w.SliceT != nil:
		return w.SliceT.Name
	case w.StructT != nil:
		return w.StructT.Name
	case w.MapT != nil:
		return w.MapT.Name
	case w.GobEncoderT != nil:
		return w.GobEncoderT.Name
	case w.BinaryMarshalerT != nil:
		return w.BinaryMarshalerT.Name

			elemOp := dec.decIgnoreOpFor(elemId, inProgress, depth+1)
			op = func(i *decInstr, state *decoderState, value reflect.Value) {
				state.dec.ignoreMap(state, *keyOp, *elemOp)
			}

		case wire.SliceT != nil:
			elemId := wire.SliceT.Elem
			elemOp := dec.decIgnoreOpFor(elemId, inProgress, depth+1)
			op = func(i *decInstr, state *decoderState, value reflect.Value) {
				state.dec.ignoreSlice(state, *elemOp)
			}

pair (-type id, encoded-type) where encoded-type is the gob encoding of a wireType
description, constructed from these types:

	type wireType struct {
		ArrayT           *ArrayType
		SliceT           *SliceType
		StructT          *StructType
		MapT             *MapType
		GobEncoderT      *gobEncoderType
		BinaryMarshalerT *gobEncoderType
		TextMarshalerT   *gobEncoderType

	}