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
an older Go version, the Go toolchain amends its defaults
to match that older Go version as closely as possible.
For example, when a Go 1.21 toolchain compiles a program,
if the work module's `go.mod` or the workspace's `go.work`

will succeed.
Such code should use a non-blocking receive instead.

These new behaviors are only enabled when the main Go program
is in a module with a `go.mod` `go` line using Go 1.23.0 or later.
When Go 1.23 builds older programs, the old behaviors remain in effect.
The new [GODEBUG setting](/doc/godebug) [`asynctimerchan=1`](/pkg/time/#NewTimer)
can be used to revert back to asynchronous channel behaviors

	//
	// Reference:
	//	http://pubs.opengroup.org/onlinepubs/009695399/utilities/pax.html
	FormatPAX

	// FormatGNU represents the GNU header format.
	//
	// The GNU header format is older than the USTAR and PAX standards and
	// is not compatible with them. The GNU format supports
	// arbitrary file sizes, filenames of arbitrary encoding and length,
	// sparse files, and other features.
	//

Arenas allocate large chunks of memory for Go values, so they're likely to
be inefficient for allocating only small amounts of small Go values. They're
best used in bulk, on the order of MiB of memory allocated on each use.

Note that by allowing for this limited form of manual memory allocation
that use-after-free bugs are possible with regular Go values. This package

<a href="#Order_of_evaluation">evaluation order</a>.
</p>

<p>
For struct literals the following rules apply:
</p>
<ul>
	<li>A key must be a field name declared in the struct type.
	</li>
	<li>An element list that does not contain any keys must
	    list an element for each struct field in the
	    order in which the fields are declared.
	</li>

error messages, debug information, and object files. In practice,
parsing these is significantly less work and more robust than parsing
C source.

Cgo first invokes gcc -E -dM on the preamble, in order to find out
about simple #defines for constants and the like. These are recorded
for later use.

Next, cgo needs to identify the kinds for each identifier. For the
identifiers C.foo, cgo generates this C program:

*/
package gmp

/*
#cgo LDFLAGS: -lgmp
#include <gmp.h>
#include <stdlib.h>

// gmp 5.0.0+ changed the type of the 3rd argument to mp_bitcnt_t,
// so, to support older versions, we wrap these two functions.
void _mpz_mul_2exp(mpz_ptr a, mpz_ptr b, unsigned long n) {
	mpz_mul_2exp(a, b, n);
}
void _mpz_div_2exp(mpz_ptr a, mpz_ptr b, unsigned long n) {
	mpz_div_2exp(a, b, n);
}

					foundAThread = true
					break
				}
				if filter == "Groups:" && strings.HasPrefix(line, "Groups:\t") {
					// https://github.com/golang/go/issues/46145
					// Containers don't reliably output this line in sorted order so manually sort and compare that.
					a := strings.Split(line[8:], " ")
					sort.Strings(a)
					got := strings.Join(a, " ")
					if got == expected[8:] {
						foundAThread = true
						break
					}

func (p *parser) parseNumeric(b []byte) int64 {
	// Check for base-256 (binary) format first.
	// If the first bit is set, then all following bits constitute a two's
	// complement encoded number in big-endian byte order.
	if len(b) > 0 && b[0]&0x80 != 0 {
		// Handling negative numbers relies on the following identity:
		//	-a-1 == ^a
		//
		// If the number is negative, we use an inversion mask to invert the

	// Since the Reader liberally reads some non-compliant files,
	// it is possible for this to be FormatUnknown.
	//
	// If the format is unspecified when Writer.WriteHeader is called,
	// then it uses the first format (in the order of USTAR, PAX, GNU)
	// capable of encoding this Header (see Format).
	Format Format
}

// sparseEntry represents a Length-sized fragment at Offset in the file.
type sparseEntry struct{ Offset, Length int64 }