details are printed before `throw` using `print` or `println` and the
messages are prefixed with "runtime:".

For unrecoverable errors where user code is expected to be at fault for the
failure (such as racing map writes), use `fatal`.

For runtime error debugging, it may be useful to run with `GOTRACEBACK=system`
or `GOTRACEBACK=crash`. The output of `panic` and `fatal` is as described by

	globalSkip(t)
	goCmd(t, "build", "-buildmode=plugin", "-o", "life.so", "./issue25756/plugin")
	goCmd(t, "build", "-o", "issue25756.exe", "./issue25756/main.go")
	// Fails intermittently, but 20 runs should cause the failure
	for n := 20; n > 0; n-- {
		t.Run(fmt.Sprint(n), func(t *testing.T) {
			t.Parallel()
			run(t, "./issue25756.exe")
		})
	}
}

// Test with main using -buildmode=pie with plugin for issue #43228

		x.mode = mapindex
		x.typ = typ.elem
		x.expr = e
		return false

	case *Interface:
		if !isTypeParam(x.typ) {
			break
		}
		// TODO(gri) report detailed failure cause for better error messages
		var key, elem Type // key != nil: we must have all maps
		mode := variable   // non-maps result mode
		// TODO(gri) factor out closure and use it for non-typeparam cases as well

	{26, "SIGVTALRM", "virtual timer expired"},
	{27, "SIGPROF", "profiling timer expired"},
	{28, "SIGWINCH", "window changed"},
	{29, "SIGIO", "I/O possible"},
	{30, "SIGPWR", "power failure"},
	{31, "SIGSYS", "bad system call"},

	{26, "SIGVTALRM", "virtual timer expired"},
	{27, "SIGPROF", "profiling timer expired"},
	{28, "SIGWINCH", "window changed"},
	{29, "SIGIO", "I/O possible"},
	{30, "SIGPWR", "power failure"},
	{31, "SIGSYS", "bad system call"},

	{26, "SIGVTALRM", "virtual timer expired"},
	{27, "SIGPROF", "profiling timer expired"},
	{28, "SIGWINCH", "window changed"},
	{29, "SIGIO", "I/O possible"},
	{30, "SIGPWR", "power failure"},
	{31, "SIGSYS", "bad system call"},

	tests = append(tests, setStringTests2...)

	for i, test := range tests {
		x, ok := new(Rat).SetString(test.in)

		if ok {
			if !test.ok {
				t.Errorf("#%d SetString(%q) expected failure", i, test.in)
			} else if x.RatString() != test.out {
				t.Errorf("#%d SetString(%q) got %s want %s", i, test.in, x.RatString(), test.out)
			}
		} else {
			if test.ok {

	l.updateLocked(now)
	l.gcEnabled = enableGC
	l.transitioning = true
	// N.B. finishGCTransition releases the lock.
	//
	// We don't release here to increase the chance that if there's a failure
	// to finish the transition, that we throw on failing to acquire the lock.
}

// finishGCTransition notifies the limiter that the GC transition is complete

	cmd.Stderr = new(bytes.Buffer)
	out, err := cmd.Output()
	t.Logf("%v:\n%s", cmd, out)
	t.Logf("stderr:\n%s", cmd.Stderr)
	if err == nil {
		t.Errorf("unexpected success; want failure due to newline in file path")
	}

through the fmt package.  For example, if a String method
calls panic("bad"), the resulting formatted message will look
like

	%!s(PANIC=bad)

The %!s just shows the print verb in use when the failure
occurred. If the panic is caused by a nil receiver to an Error
or String method, however, the output is the undecorated
string, "<nil>".

# Scanning

An analogous set of functions scans formatted text to yield