The files should be in the subdirectory for the package with the new
API, and should be named after the issue number of the API proposal.
For example, if the directory `6-stdlib/99-minor` is present,
then an `api/next` file with the line

    pkg net/http, function F #12345

should have a corresponding file named `doc/next/6-stdlib/99-minor/net/http/12345.md`.
At a minimum, that file should contain either a full sentence or a TODO,

// io.ByteScanner, and io.RuneScanner interfaces by reading from
// a byte slice.
// Unlike a [Buffer], a Reader is read-only and supports seeking.
// The zero value for Reader operates like a Reader of an empty slice.
type Reader struct {
	s        []byte
	i        int64 // current reading index
	prevRune int   // index of previous rune; or < 0
}

pkg time, const ANSIC = "Mon Jan _2 15:04:05 2006"
pkg time, const April = 4
pkg time, const August = 8
pkg time, const December = 12
pkg time, const February = 2
pkg time, const Friday = 5
pkg time, const Hour = 3600000000000
pkg time, const January = 1
pkg time, const July = 7
pkg time, const June = 6
pkg time, const Kitchen = "3:04PM"
pkg time, const March = 3

Joe Tsai <******@****.***> 1503947278 -0700

Joe Tsai <******@****.***> 1503947278 -0700

pkg crypto/x509, type RevocationList struct, NextUpdate time.Time
pkg crypto/x509, type RevocationList struct, Number *big.Int
pkg crypto/x509, type RevocationList struct, RevokedCertificates []pkix.RevokedCertificate
pkg crypto/x509, type RevocationList struct, SignatureAlgorithm SignatureAlgorithm
pkg crypto/x509, type RevocationList struct, ThisUpdate time.Time
pkg database/sql, method (*DB) SetConnMaxIdleTime(time.Duration)

			// and an invalid pre-Go1.8 file.
			//
			// See https://golang.org/issues/12594
			// See https://golang.org/issues/21005
			if p2.err != nil {
				hdr.AccessTime, hdr.ChangeTime = time.Time{}, time.Time{}
				ustar := tr.blk.toUSTAR()
				if s := p.parseString(ustar.prefix()); isASCII(s) {
					prefix = s
				}
				hdr.Format = FormatUnknown // Buggy file is not GNU
			}
		}
		if len(prefix) > 0 {

	typedef unsigned long int mp_limb_t;

	typedef struct
	{
		int _mp_alloc;
		int _mp_size;
		mp_limb_t *_mp_d;
	} __mpz_struct;

	typedef __mpz_struct mpz_t[1];

Cgo generates:

	type _C_int int32
	type _C_mp_limb_t uint64
	type _C___mpz_struct struct {
		_mp_alloc _C_int;
		_mp_size _C_int;
		_mp_d *_C_mp_limb_t;
	}
	type _C_mpz_t [1]_C___mpz_struct

			j++
		} else {
			j--
		}
		line := tmp.String() // We use the string-valued token here, for variety.
		if s.Text() != line {
			t.Errorf("%d: bad line: %d %d\n%.100q\n%.100q\n", lineNum, len(s.Bytes()), len(line), s.Text(), line)
		}
	}
	err := s.Err()
	if err != nil {
		t.Fatal(err)
	}
}

// Test that the line splitter errors out on a long line.
func TestScanLineTooLong(t *testing.T) {

//go:build !(windows || js || wasip1)

package main

import (
	"regexp"
	"strings"
	"testing"
)

func TestExitCodeFilter(t *testing.T) {
	// Write text to the filter one character at a time.
	var out strings.Builder
	f, exitStr := newExitCodeFilter(&out)
	// Embed a "fake" exit code in the middle to check that we don't get caught on it.
	pre := "abc" + exitStr + "123def"
	text := pre + exitStr + `1`