declarations and definitions. These may then be referred to from Go
code as though they were defined in the package "C". All names
declared in the preamble may be used, even if they start with a
lower-case letter. Exception: static variables in the preamble may
not be referenced from Go code; static functions are permitted.

See $GOROOT/cmd/cgo/internal/teststdio and $GOROOT/misc/cgo/gmp for examples. See

unicode_letter = /* a Unicode code point classified as "Letter" */ .
unicode_digit  = /* a Unicode code point classified as "Number, decimal digit" */ .
</pre>

<p>
In <a href="https://www.unicode.org/versions/Unicode8.0.0/">The Unicode Standard 8.0</a>,
Section 4.5 "General Category" defines a set of character categories.
Go treats all characters in any of the Letter categories Lu, Ll, Lt, Lm, or Lo

	{"$0xfffffffffffff001", "$-4095"},
	{"$1", "$1"},
	{"$1.0", "$(1.0)"},
	{"$10", "$10"},
	{"$1000", "$1000"},
	{"$1000000", "$1000000"},
	{"$1000000000", "$1000000000"},
	{"$__tsan_func_enter(SB)", "$__tsan_func_enter(SB)"},
	{"$main(SB)", "$main(SB)"},
	{"$masks<>(SB)", "$masks<>(SB)"},
	{"$setg_gcc<>(SB)", "$setg_gcc<>(SB)"},
	{"$shifts<>(SB)", "$shifts<>(SB)"},
	{"$~(1<<63)", "$9223372036854775807"},

	s.IsIdentRune = isIdentRune
	return &Tokenizer{
		s:    &s,
		base: src.NewFileBase(name, objabi.AbsFile(objabi.WorkingDir(), name, *flags.TrimPath)),
		line: 1,
		file: file,
	}
}

// We want center dot (·) and division slash (∕) to work as identifier characters.
func isIdentRune(ch rune, i int) bool {
	if unicode.IsLetter(ch) {
		return true
	}
	switch ch {
	case '_': // Underscore; traditional.
		return true

America/Mexico_City America/Miquelon America/Moncton America/Monterrey America/Montevideo America/Montreal America/Montserrat America/Nassau America/New_York America/Nipigon America/Nome America/Noronha America/North_Dakota/Beulah America/North_Dakota/Center America/North_Dakota/New_Salem America/Nuuk America/Ojinaga America/Panama America/Pangnirtung America/Paramaribo America/Phoenix America/Port-au-Prince America/Port_of_Spain America/Porto_Acre America/Porto_Velho America/Puerto_Rico America/Punta_Arenas...

// non-pointers in this type.
// TODO: Currently our best solution is to find these manually and list them as
// they come up. A better solution is desired.
// Note: DEPRECATED. There is now a better solution. Search for incomplete in this file.
func (c *typeConv) badPointerTypedef(dt *dwarf.TypedefType) bool {
	if c.badCFType(dt) {
		return true
	}
	if c.badJNI(dt) {

		t.Fatal("addr2line output must have 2 lines")
	}
	funcname = f[0]
	pathAndLineNo := f[1]
	f = strings.Split(pathAndLineNo, ":")
	if runtime.GOOS == "windows" && len(f) == 3 {
		// Reattach drive letter.
		f = []string{f[0] + ":" + f[1], f[2]}
	}
	if len(f) != 2 {
		t.Fatalf("no line number found in %q", pathAndLineNo)
	}
	return funcname, f[0], f[1]
}

const symName = "cmd/addr2line.TestAddr2Line"

	AND	$1, ZR                              // fb0340b2ff031b8a
	ANDW	$1, ZR                              // fb030032ff031b0a
	// TODO: this could have better encoding
	ANDW	$-1, R10                            // 1b0080124a011b0a
	AND	$8, R0, RSP                         // 1f007d92
	ORR	$8, R0, RSP                         // 1f007db2

pkg syscall (darwin-arm64), const RTF_PROXY ideal-int
pkg syscall (darwin-arm64), const RTF_REJECT = 8
pkg syscall (darwin-arm64), const RTF_REJECT ideal-int
pkg syscall (darwin-arm64), const RTF_ROUTER = 268435456
pkg syscall (darwin-arm64), const RTF_ROUTER ideal-int
pkg syscall (darwin-arm64), const RTF_STATIC = 2048
pkg syscall (darwin-arm64), const RTF_STATIC ideal-int
pkg syscall (darwin-arm64), const RTF_UP = 1

//
// [ZIP specification]: https://support.pkware.com/pkzip/appnote
type FileHeader struct {
	// Name is the name of the file.
	//
	// It must be a relative path, not start with a drive letter (such as "C:"),
	// and must use forward slashes instead of back slashes. A trailing slash
	// indicates that this file is a directory and should have no data.
	Name string