}
}

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

At that point, the program is terminated and the error
condition is reported, including the value of the argument to <code>panic</code>.
This termination sequence is called <i>panicking</i>.
</p>

<pre>
panic(42)
panic("unreachable")
panic(Error("cannot parse"))
</pre>

<p>
The <code>recover</code> function allows a program to manage behavior
of a panicking goroutine.

	b, err := hex.DecodeString(s)
	if err != nil {
		panic(err)
	}
	return b
}

func returnBigZipBytes() (r io.ReaderAt, size int64) {
	b := biggestZipBytes()
	for i := 0; i < 2; i++ {
		r, err := NewReader(bytes.NewReader(b), int64(len(b)))
		if err != nil {
			panic(err)
		}
		f, err := r.File[0].Open()
		if err != nil {
			panic(err)
		}
		b, err = io.ReadAll(f)

			t.Fatalf("stdPackages contains unexpected package %s", pkg)
		}
	}
}

func TestIssue64958(t *testing.T) {
	defer func() {
		if x := recover(); x != nil {
			t.Errorf("expected no panic; recovered %v", x)
		}
	}()

	testenv.MustHaveGoBuild(t)

	for _, context := range contexts {
		w := NewWalker(context, "testdata/src/issue64958")
		pkg, err := w.importFrom("p", "", 0)

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

	if _, dup := decompressors.LoadOrStore(method, dcomp); dup {
		panic("decompressor already registered")
	}
}

// RegisterCompressor registers custom compressors for a specified method ID.
// The common methods [Store] and [Deflate] are built in.
func RegisterCompressor(method uint16, comp Compressor) {
	if _, dup := compressors.LoadOrStore(method, comp); dup {
		panic("compressor already registered")
	}
}

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