func drain(input *Input) string {
	var buf strings.Builder
	for {
		tok := input.Next()
		if tok == scanner.EOF {
			return buf.String()
		}
		if tok == '#' {
			continue
		}
		if buf.Len() > 0 {
			buf.WriteByte('.')
		}
		buf.WriteString(input.Text())
	}
}

type badLexTest struct {
	input string
	error string
}

		errors[fileline] = line
	}

	// Reconstruct expected errors by independently "parsing" the input.
	data, err := os.ReadFile(input)
	if err != nil {
		t.Error(err)
		return
	}
	lineno := 0
	lines := strings.Split(string(data), "\n")
	for _, line := range lines {
		lineno++

		fileline := fmt.Sprintf("%s:%d", input, lineno)
		if m := errRE.FindStringSubmatch(line); m != nil {
			all := m[1]

// just enough to support pprof.
//
// Usage:
//
//	go tool addr2line binary
//
// Addr2line reads hexadecimal addresses, one per line and with optional 0x prefix,
// from standard input. For each input address, addr2line prints two output lines,
// first the name of the function containing the address and second the file:line
// of the source code corresponding to that address.
//

	}
}

// NewLexer returns a lexer for the named file and the given link context.
func NewLexer(name string) TokenReader {
	input := NewInput(name)
	fd, err := os.Open(name)
	if err != nil {
		log.Fatalf("%s\n", err)
	}
	input.Push(NewTokenizer(name, fd, fd))
	return input
}

// The other files in this directory each contain an implementation of TokenReader.

<p>
This document is a quick outline of the unusual form of assembly language used by the <code>gc</code> Go compiler.
The document is not comprehensive.
</p>

<p>
The assembler is based on the input style of the Plan 9 assemblers, which is documented in detail
<a href="https://9p.io/sys/doc/asm.html">elsewhere</a>.
If you plan to write assembly language, you should read that document although much of it is Plan 9-specific.

		Enable spectre mitigations in list (all, ret).
	-trimpath prefix
		Remove prefix from recorded source file paths.
	-v
		Print debug output.

Input language:

The assembler uses mostly the same syntax for all architectures,
the main variation having to do with addressing modes. Input is
run through a simplified C preprocessor that implements #include,
#define, #ifdef/endif, but not #if or ##.

		n += wasSpace & ^isSpace
		wasSpace = isSpace
	}

	if setBits >= utf8.RuneSelf {
		// Some runes in the input slice are not ASCII.
		return FieldsFunc(s, unicode.IsSpace)
	}

	// ASCII fast path
	a := make([][]byte, n)
	na := 0
	fieldStart := 0
	i := 0
	// Skip spaces in the front of the input.
	for i < len(s) && asciiSpace[s[i]] != 0 {
		i++
	}
	fieldStart = i
	for i < len(s) {

	ErrInvalidUnreadRune = errors.New("bufio: invalid use of UnreadRune")
	ErrBufferFull        = errors.New("bufio: buffer full")
	ErrNegativeCount     = errors.New("bufio: negative count")
)

// Buffered input.

// Reader implements buffering for an io.Reader object.
type Reader struct {
	buf          []byte
	rd           io.Reader // reader provided by the client
	r, w         int       // buf read and write positions

)

// A Stack is a stack of TokenReaders. As the top TokenReader hits EOF,
// it resumes reading the next one down.
type Stack struct {
	tr []TokenReader
}

// Push adds tr to the top (end) of the input stack. (Popping happens automatically.)
func (s *Stack) Push(tr TokenReader) {
	s.tr = append(s.tr, tr)
}

func (s *Stack) Next() ScanToken {
	tos := s.tr[len(s.tr)-1]
	tok := tos.Next()

// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This input was created by taking the instruction productions in
// the old assembler's (5a's) grammar and hand-writing complete
// instructions for each rule, to guarantee we cover the same space.

#include "../../../../../runtime/textflag.h"

TEXT	foo(SB), DUPOK|NOSPLIT, $0

// ADD
//