}
	if e.isDir {
		return &openDir{e, r.openReadDir(name), 0}, nil
	}
	rc, err := e.file.Open()
	if err != nil {
		return nil, err
	}
	return rc.(fs.File), nil
}

func split(name string) (dir, elem string, isDir bool) {
	if len(name) > 0 && name[len(name)-1] == '/' {
		isDir = true
		name = name[:len(name)-1]
	}
	i := len(name) - 1
	for i >= 0 && name[i] != '/' {
		i--

// into Go.
func testCallbackCallersSEH(t *testing.T) {
	testenv.SkipIfOptimizationOff(t) // This test requires inlining.
	if runtime.Compiler != "gc" {
		// The exact function names are not going to be the same.
		t.Skip("skipping for non-gc toolchain")
	}
	if runtime.GOARCH != "amd64" {
		// TODO: support SEH on other architectures.
		t.Skip("skipping on non-amd64")
	}

		w.emitf("type %s = %s", name, w.typeString(typ))
		return
	}
	if tparams := obj.Type().(*types.Named).TypeParams(); tparams != nil {
		var buf bytes.Buffer
		buf.WriteString(name)
		w.writeTypeParams(&buf, tparams, true)
		name = buf.String()
	}
	switch typ := typ.Underlying().(type) {
	case *types.Struct:
		w.emitStructType(name, typ)
	case *types.Interface:
		w.emitIfaceType(name, typ)

struct {
	T1        // field name is T1
	*T2       // field name is T2
	P.T3      // field name is T3
	*P.T4     // field name is T4
	x, y int  // field names are x and y
}
</pre>

<p>
The following declaration is illegal because field names must be unique
in a struct type:
</p>

<pre>
struct {
	T     // conflicts with embedded field *T and *P.T

// invalid usage. opReadRuneX constants are chosen such that
// converted to int they correspond to the rune size that was read.
type readOp int8

// Don't use iota for these, as the values need to correspond with the
// names and comments, which is easier to see when being explicit.
const (
	opRead      readOp = -1 // Any other read operation.
	opInvalid   readOp = 0  // Non-read operation.
	opReadRune1 readOp = 1  // Read rune of size 1.

func (in *Input) define() {
	name := in.macroName()
	args, tokens := in.macroDefinition(name)
	in.defineMacro(name, args, tokens)
}

// defineMacro stores the macro definition in the Input.
func (in *Input) defineMacro(name string, args []string, tokens []Token) {
	if in.macros[name] != nil {
		in.Error("redefinition of macro:", name)
	}
	in.macros[name] = &Macro{
		name:   name,
		args:   args,
		tokens: tokens,

//	}
	PLD	(R1)
	PLD	4(R1)

//
// RET
//
//	LTYPEA cond
//	{
//		outcode($1, $2, &nullgen, 0, &nullgen);
//	}
	BEQ	2(PC)
	RET

// More B/BL cases, and canonical names JMP, CALL.

	BEQ	2(PC)
	B	foo(SB) // JMP foo(SB)
	BL	foo(SB) // CALL foo(SB)
	BEQ	2(PC)
	JMP	foo(SB)
	CALL	foo(SB)

// CMPF and CMPD are special.
	CMPF F1, F2
	CMPD F1, F2

// AND

	CASPW	(R6, R7), (R8), (R4, R5)             // 047d2608
	CASPD	(R2, R3), (R2), (R8, R9)             // 487c2248

// RET
	RET
	RET	foo(SB)

// B/BL/B.cond cases, and canonical names JMP, CALL.
	BL	1(PC)      // CALL 1(PC)
	BL	(R2)       // CALL (R2)
	BL	foo(SB)    // CALL foo(SB)
	BL	bar<>(SB)  // CALL bar<>(SB)
	B	foo(SB)    // JMP foo(SB)
	BEQ	1(PC)
	BEQ	2(PC)
	TBZ	$1, R1, 2(PC)

	//
	//	LRETRN	comma // asm doesn't support the trailing comma.
	//	{
	//		outcode(int($1), &nullgen, 0, &nullgen);
	//	}
	SYSCALL
	BEQ	R1, 2(PC)
	RET


	// More JMP/JAL cases, and canonical names JMP, CALL.

	JAL	foo(SB)	// CALL foo(SB)
	BEQ	R1, 2(PC)
	JMP	foo(SB)
	CALL	foo(SB)
	RET	foo(SB)

	// unary operation
	NEGW	R1, R2 // 00011023
	CLZ	R1, R2 // 70221020
	CLO	R1, R2 // 70221021

Some, such as `http2client` and `http2server`,
will be maintained much longer, even indefinitely.

When possible, each GODEBUG setting has an associated
[runtime/metrics](/pkg/runtime/metrics/) counter
named `/godebug/non-default-behavior/<name>:events`
that counts the number of times a particular program's
behavior has changed based on a non-default value
for that setting.
For example, when `GODEBUG=http2client=0` is set,