(*ast.File)(nil),
		(*ast.Ident)(nil),
	}
	var fileVersion string // "" => no check
	inspect.Preorder(nodeFilter, func(n ast.Node) {
		switch n := n.(type) {
		case *ast.File:
			if isGenerated(n) {
				// Suppress diagnostics in generated files (such as cgo).
				fileVersion = ""
			} else {
				fileVersion = versions.Lang(versions.FileVersion(pass.TypesInfo, n))
				// (may be "" if unknown)
			}

func (check *Checker) allowVersion(at poser, v goVersion) bool {
	fileVersion := check.conf.GoVersion
	if pos := at.Pos(); pos.IsKnown() {
		fileVersion = check.versions[pos.FileBase()]
	}

	// We need asGoVersion (which calls version.Lang) below
	// because fileVersion may be the (unaltered) Config.GoVersion
	// string which may contain dot-release information.
	version := asGoVersion(fileVersion)

	return !version.isValid() || version.cmp(v) >= 0
}

package versions

import (
	"go/ast"
	"go/types"
)

// FileVersion returns a file's Go version.
// The reported version is an unknown Future version if a
// version cannot be determined.
func FileVersion(info *types.Info, file *ast.File) string {
	// In tools built with Go >= 1.22, the Go version of a file
	// follow a cascades of sources:
	// 1) types.Info.FileVersion, which follows the cascade:
	//   1.a) file version (ast.File.GoVersion),

		// unlike file versions which are Go language versions only, if valid.)
		v := check.conf.GoVersion

		fileVersion := asGoVersion(file.GoVersion)
		if fileVersion.isValid() {
			// use the file version, if applicable
			// (file versions are either the empty string or of the form go1.dd)
			if pkgVersionOk {
				cmp := fileVersion.cmp(check.version)
				// Go 1.21 introduced the feature of setting the go.mod

		// unlike file versions which are Go language versions only, if valid.)
		v := check.conf.GoVersion

		fileVersion := asGoVersion(file.GoVersion)
		if fileVersion.isValid() {
			// use the file version, if applicable
			// (file versions are either the empty string or of the form go1.dd)
			if pkgVersionOk {
				cmp := fileVersion.cmp(check.version)
				// Go 1.21 introduced the feature of setting the go.mod

	if !bytes.HasPrefix(m.mapping.Data, hdr) {
		return nil, fmt.Errorf("counter: header mismatch")
	}
	m.hdrLen = uint32(len(hdr))

	return m, nil
}

const (
	FileVersion = "v1"
	hdrPrefix   = "# telemetry/counter file " + FileVersion + "\n"
	recordUnit  = 32
	maxMetaLen  = 512
	numHash     = 512 // 2kB for hash table
	maxNameLen  = 4 * 1024
	limitOff    = 0
	hashOff     = 4
	pageSize    = 16 * 1024

		{"go1.21.1", "go1.19", "go1.19"},     // file downgrade permitted (module version is >= go1.21)
	} {
		var src string
		if test.fileVersion != "" {
			src = "//go:build " + test.fileVersion + "\n"
		}
		src += "package p"

		conf := Config{GoVersion: test.goVersion}
		versions := make(map[*syntax.PosBase]string)
		var info Info
		info.FileVersions = versions

		{"go1.21.1", "go1.19", "go1.19"},     // file downgrade permitted (module version is >= go1.21)
	} {
		var src string
		if test.fileVersion != "" {
			src = "//go:build " + test.fileVersion + "\n"
		}
		src += "package p"

		conf := Config{GoVersion: test.goVersion}
		versions := make(map[*ast.File]string)
		var info Info
		info.FileVersions = versions