+ Keep the title as short as possible. ideally under 76 characters or shorter
+ No Markdown
+ The first PR comment (this one) is wrapped at 76 characters, unless it's
  really needed (ASCII art, table, or long link)
+ If there is a corresponding issue, add either `Fixes #1234` or `Updates #1234`
  (the latter if this is not a complete fix) to this comment
+ If referring to a repo other than `golang/go` you can use the

	return t.line
}

func (t *Tokenizer) Col() int {
	return t.s.Pos().Column
}

func (t *Tokenizer) Next() ScanToken {
	s := t.s
	for {
		t.tok = ScanToken(s.Scan())
		if t.tok != scanner.Comment {
			break
		}
		text := s.TokenText()
		t.line += strings.Count(text, "\n")
		if constraint.IsGoBuild(text) {
			t.tok = BuildComment
			break
		}
	}
	switch t.tok {
	case '\n':

// Copyright 2020 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.

#define X 1

	//	// +godefs map struct_in_addr6 [16]byte
	//
	for _, g := range f.Comments {
		for _, c := range g.List {
			i := strings.Index(c.Text, "+godefs map")
			if i < 0 {
				continue
			}
			s := strings.TrimSpace(c.Text[i+len("+godefs map"):])
			i = strings.Index(s, " ")
			if i < 0 {
				fmt.Fprintf(os.Stderr, "invalid +godefs map comment: %s\n", c.Text)
				continue
			}

		return "float constant"
	case scanner.Char:
		return "rune constant"
	case scanner.String:
		return "string constant"
	case scanner.RawString:
		return "raw string constant"
	case scanner.Comment:
		return "comment"
	default:
		return fmt.Sprintf("%q", rune(t))
	}
}

// NewLexer returns a lexer for the named file and the given link context.
func NewLexer(name string) TokenReader {
	input := NewInput(name)

it compiles into a shared object (.so) that is dynamically linked into
any 6.out that imports the first two files.

The stanza

	// #include <gmp.h>
	import "C"

is a signal to cgo.  The doc comment on the import of "C" provides
additional context for the C file.  Here it is just a single #include
but it could contain arbitrary C definitions to be imported and used.

			"B",
		),
		"THIS.\n",
	},
	{
		"nested #define with args",
		lines(
			"#define A #define B(x) x",
			"A",
			"B(THIS)",
		),
		"THIS.\n",
	},
	/* This one fails. See comment in Slice.Col.
	{
		"nested #define with args",
		lines(
			"#define A #define B (x) x",
			"A",
			"B(THIS)",
		),
		"x.\n",
	},
	*/
}

func TestLex(t *testing.T) {

The `initial` and `next` subdirectories of this directory are for release notes.

## For developers

Release notes should be added to `next` by editing existing files or creating
new files. **Do not add RELNOTE=yes comments in CLs.** Instead, add a file to
the CL (or ask the author to do so).

At the end of the development cycle, the files will be merged by being
concatenated in sorted order by pathname. Files in the directory matching the