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

of the location.
</p>


<h3 id="Handling_panics">Handling panics</h3>

<p> Two built-in functions, <code>panic</code> and <code>recover</code>,
assist in reporting and handling <a href="#Run_time_panics">run-time panics</a>
and program-defined error conditions.
</p>

<pre class="grammar">
func panic(interface{})
func recover() interface{}
</pre>

<p>

func (r *Reader) WriteTo(w io.Writer) (n int64, err error) {
	r.prevRune = -1
	if r.i >= int64(len(r.s)) {
		return 0, nil
	}
	b := r.s[r.i:]
	m, err := w.Write(b)
	if m > len(b) {
		panic("bytes.Reader.WriteTo: invalid Write count")
	}
	r.i += int64(m)
	n = int64(m)
	if m != len(b) && err == nil {
		err = io.ErrShortWrite
	}
	return
}

//
// It panics if count is negative or if the result of (len(b) * count)
// overflows.
func Repeat(b []byte, count int) []byte {
	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")
	}

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

		pkgPrefix:   pkgPrefix,
	}
}

// panicOnError is enabled when testing to abort execution on the first error
// and turn it into a recoverable panic.
var panicOnError bool

func (p *Parser) errorf(format string, args ...interface{}) {
	if panicOnError {
		panic(fmt.Errorf(format, args...))
	}
	if p.lineNum == p.errorLine {
		// Only one error per line.
		return
	}
	p.errorLine = p.lineNum
	if p.lex != nil {

			name:   name,
			args:   nil,
			tokens: Tokenize(value),
		}
	}
	return macros
}

var panicOnError bool // For testing.

func (in *Input) Error(args ...interface{}) {
	if panicOnError {
		panic(fmt.Errorf("%s:%d: %s", in.File(), in.Line(), fmt.Sprintln(args...)))
	}
	fmt.Fprintf(os.Stderr, "%s:%d: %s", in.File(), in.Line(), fmt.Sprintln(args...))
	os.Exit(1)
}

#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>

/* Test calling panic from C.  This is what SWIG does.  */

extern void crosscall2(void (*fn)(void *, int), void *, int);
extern void _cgo_panic(void *, int);
extern void _cgo_allocate(void *, int);

void
callPanic(void)
{
	struct { const char *p; } a;
	a.p = "panic from C";
	crosscall2(_cgo_panic, &a, sizeof a);
	*(int*)1 = 1;

//
// Buffer panics if it is called after scanning has started.
func (s *Scanner) Buffer(buf []byte, max int) {
	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.

//go:build gccgo

#include "_cgo_export.h"
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>

/* Test calling panic from C.  This is what SWIG does.  */

extern void _cgo_panic(const char *);
extern void *_cgo_allocate(size_t);

void
callPanic(void)
{
	_cgo_panic("panic from C");