// The general form of a test input line is:
		//	// comment
		//	INST args [// printed form] [// hex encoding]
		parts := strings.Split(line, "//")
		printed := strings.TrimSpace(parts[0])
		if printed == "" || strings.HasSuffix(printed, ":") { // empty or label
			continue
		}
		seq++

		var hexes string
		switch len(parts) {
		default:
			t.Errorf("%s:%d: unable to understand comments: %s", input, lineno, line)
		case 1:

		return
	}
	skipParts, _ := slices.BinarySearchFunc(r.buf, off, func(rb repeatedByte, off int64) int {
		return cmp.Compare(rb.off+rb.n, off)
	})
	parts := r.buf[skipParts:]
	if len(parts) > 0 {
		skipBytes := off - parts[0].off
		for _, part := range parts {
			repeat := int(min(part.n-skipBytes, int64(len(p)-n)))
			memset(p[n:n+repeat], part.b)
			n += repeat
			if n == len(p) {
				return
			}

		}
		return errorf("%v: %w", cmd, err)
	}

	parts := strings.SplitN(string(bytes.TrimSpace(out)), ":", 4)
	if len(parts) < 2 {
		return errorf("%v: missing ':' in output: %q", cmd, out)
	}
	importPath = parts[0]
	if importPath == "" || importPath == "." {
		return errorf("current directory does not have a Go import path")
	}
	isStd, err = strconv.ParseBool(parts[1])
	if err != nil {

Even so, Go provides a mechanism called GODEBUG to
reduce the impact such changes have on Go developers
using newer toolchains to compile old code.

A GODEBUG setting is a `key=value` pair
that controls the execution of certain parts of a Go program.
The environment variable `GODEBUG`
can hold a comma-separated list of these settings.
For example, if a Go program is running in an environment that contains

	GODEBUG=http2client=0,http2server=0

as C.stdout, or functions such as C.putchar.

If the import of "C" is immediately preceded by a comment, that
comment, called the preamble, is used as a header when compiling
the C parts of the package. For example:

	// #include <stdio.h>
	// #include <errno.h>
	import "C"

The preamble may contain any C code, including function and variable

// which is allowed for by the PAX specification, but not always portable.
func parsePAXTime(s string) (time.Time, error) {
	const maxNanoSecondDigits = 9

	// Split string into seconds and sub-seconds parts.
	ss, sn, _ := strings.Cut(s, ".")

	// Parse the seconds.
	secs, err := strconv.ParseInt(ss, 10, 64)
	if err != nil {
		return time.Time{}, ErrHeader
	}
	if len(sn) == 0 {

float64     the set of all IEEE 754 64-bit floating-point numbers

complex64   the set of all complex numbers with float32 real and imaginary parts
complex128  the set of all complex numbers with float64 real and imaginary parts

byte        alias for uint8
rune        alias for int32
</pre>

<p>
The value of an <i>n</i>-bit integer is <i>n</i> bits wide and represented using

float64     the set of all IEEE 754 64-bit floating-point numbers

complex64   the set of all complex numbers with float32 real and imaginary parts
complex128  the set of all complex numbers with float64 real and imaginary parts

byte        alias for uint8
rune        alias for int32
</pre>

<p>
The value of an <i>n</i>-bit integer is <i>n</i> bits wide and represented using

type float64 float64

// complex64 is the set of all complex numbers with float32 real and
// imaginary parts.
type complex64 complex64

// complex128 is the set of all complex numbers with float64 real and
// imaginary parts.
type complex128 complex128

// string is the set of all strings of 8-bit bytes, conventionally but not