}
}

type panicReader struct{ panic bool }

func (r panicReader) Read(p []byte) (int, error) {
	if r.panic {
		panic("oops")
	}
	return 0, io.EOF
}

// Make sure that an empty Buffer remains empty when
// it is "grown" before a Read that panics
func TestReadFromPanicReader(t *testing.T) {

	// First verify non-panic behaviour
	var buf Buffer

func setArch(goarch string) (*arch.Arch, *obj.Link) {
	buildcfg.GOOS = "linux" // obj can handle this OS for all architectures.
	buildcfg.GOARCH = goarch
	architecture := arch.Set(goarch, false)
	if architecture == nil {
		panic("asm: unrecognized architecture " + goarch)
	}
	ctxt := obj.Linknew(architecture.LinkArch)
	ctxt.Pkgpath = "pkg"
	return architecture, ctxt
}

func newParser(goarch string) *Parser {

	uintptr_t _cgo_wait_runtime_init_done(void) { return 0; }
	void _cgo_release_context(uintptr_t ctxt) { }
	char* _cgo_topofstack(void) { return (char*)0; }
	void _cgo_allocate(void *a, int c) { }
	void _cgo_panic(void *a, int c) { }
	void _cgo_reginit(void) { }

The extra functions here are stubs to satisfy the references in the C
code generated for gcc. The build process links this stub, along with

// another n bytes. After Grow(n), at least n bytes can be written to the
// buffer without another allocation.
// If n is negative, Grow will panic.
// If the buffer can't grow it will panic with [ErrTooLarge].
func (b *Buffer) Grow(n int) {
	if n < 0 {
		panic("bytes.Buffer.Grow: negative count")
	}
	m := b.grow(n)
	b.buf = b.buf[:m]
}

// Write appends the contents of p to the buffer, growing the buffer as

The [GODEBUG History](#history) gives the exact defaults for each Go toolchain version.
For example, Go 1.21 introduces the `panicnil` setting,
controlling whether `panic(nil)` is allowed;
it defaults to `panicnil=0`, making `panic(nil)` a run-time error.
Using `panicnil=1` restores the behavior of Go 1.20 and earlier.

When compiling a work module or workspace that declares

	if s.scanCalled {
		panic("Buffer called after Scan")
	}
	s.buf = buf[0:cap(buf)]
	s.maxTokenSize = max
}

// Split sets the split function for the [Scanner].
// The default split function is [ScanLines].
//
// Split panics if it is called after scanning has started.
func (s *Scanner) Split(split SplitFunc) {
	if s.scanCalled {
		panic("Split called after Scan")
	}
	s.split = split

	n, err := b.Read(rdbuf)
	if err != nil {
		panic(err)
	}
	fmt.Println(n)
	fmt.Println(b.String())
	fmt.Println(string(rdbuf))
	// Output:
	// 1
	// bcde
	// a
}

func ExampleBuffer_ReadByte() {
	var b bytes.Buffer
	b.Grow(64)
	b.Write([]byte("abcde"))
	c, err := b.ReadByte()
	if err != nil {
		panic(err)
	}
	fmt.Println(c)
	fmt.Println(b.String())

		copy(b.toSTAR().trailer(), trailerSTAR)
	case format.has(FormatUSTAR | FormatPAX):
		copy(b.toUSTAR().magic(), magicUSTAR)
		copy(b.toUSTAR().version(), versionUSTAR)
	default:
		panic("invalid format")
	}

	// Update checksum.
	// This field is special in that it is terminated by a NULL then space.
	var f formatter
	field := b.toV7().chksum()

func close(c chan<- Type)

// The panic built-in function stops normal execution of the current
// goroutine. When a function F calls panic, normal execution of F stops
// immediately. Any functions whose execution was deferred by F are run in
// the usual way, and then F returns to its caller. To the caller G, the
// invocation of F then behaves like a call to panic, terminating G's

	if count == 0 {
		return []byte{}
	}

	// Since we cannot return an error on overflow,
	// we should panic if the repeat will generate an overflow.
	// See golang.org/issue/16237.
	if count < 0 {
		panic("bytes: negative Repeat count")
	}
	if len(b) >= maxInt/count {
		panic("bytes: Repeat output length overflow")
	}
	n := len(b) * count

	if len(b) == 0 {
		return []byte{}
	}