error      string
	parseError string

	name                 string
	synopsis             string // doc.Synopsis of package comment... Compute synopsis on all of these?
	pkgName              string
	ignoreFile           bool   // starts with _ or . or should otherwise always be ignored
	binaryOnly           bool   // cannot be rebuilt from source (has //go:binary-only-package comment)

	for _, f := range pass.Files {
		checkGoFile(pass, f)
	}
	for _, name := range pass.OtherFiles {
		if err := checkOtherFile(pass, name); err != nil {
			return nil, err
		}
	}
	for _, name := range pass.IgnoredFiles {
		if strings.HasSuffix(name, ".go") {
			f, err := parser.ParseFile(pass.Fset, name, nil, parser.ParseComments)
			if err != nil {
				// Not valid Go source code - not our job to diagnose, so ignore.
				return nil, nil

	if slicesContains(pass.OtherFiles, filename) ||
		slicesContains(pass.IgnoredFiles, filename) {
		return nil
	}
	for _, f := range pass.Files {
		// TODO(adonovan): use go1.20 f.FileStart
		if pass.Fset.File(f.Pos()).Name() == filename {
			return nil
		}
	}
	return fmt.Errorf("Pass.ReadFile: %s is not among OtherFiles, IgnoredFiles, or names of Files", filename)
}

	for _, f := range pass.Files {
		checkGoFile(pass, f)
	}
	for _, name := range pass.OtherFiles {
		if err := checkOtherFile(pass, name); err != nil {
			return nil, err
		}
	}
	for _, name := range pass.IgnoredFiles {
		if strings.HasSuffix(name, ".go") {
			f, err := parser.ParseFile(pass.Fset, name, nil, parser.ParseComments)
			if err != nil {
				// Not valid Go source code - not our job to diagnose, so ignore.
				continue

func packageDir(pkg *packages.Package) string {
	if len(pkg.GoFiles) > 0 {
		return filepath.Dir(pkg.GoFiles[0])
	}
	if len(pkg.IgnoredFiles) > 0 {
		return filepath.Dir(pkg.IgnoredFiles[0])
	}
	return ""
}

type FileFormat struct {
	Rules        []Rule
	InverseRules []Rule

	path string
}

// A single import restriction rule.

reporting diagnostics and other information back to the driver.

	type Pass struct {
		Fset         *token.FileSet
		Files        []*ast.File
		OtherFiles   []string
		IgnoredFiles []string
		Pkg          *types.Package
		TypesInfo    *types.Info
		ResultOf     map[*Analyzer]interface{}
		Report       func(Diagnostic)
		...
	}

	for _, f := range pass.Files {
		checkGoFile(pass, f)
	}
	for _, name := range pass.OtherFiles {
		if err := checkOtherFile(pass, name); err != nil {
			return nil, err
		}
	}
	for _, name := range pass.IgnoredFiles {
		if strings.HasSuffix(name, ".go") {
			f, err := parser.ParseFile(pass.Fset, name, nil, parser.ParseComments|parser.SkipObjectResolution)
			if err != nil {

				item.Source = info.Source
			}
			if err := fn(item, nil); err != nil {
				errs = append(errs, err)
			}
		}
		return utilerrors.NewAggregate(errs)
	})
}

func ignoreFile(path string, extensions []string) bool {
	if len(extensions) == 0 {
		return false
	}
	ext := filepath.Ext(path)
	for _, s := range extensions {
		if s == ext {
			return false
		}
	}

				if x, err := constraint.Parse(text); err == nil {
					if !ctxt.eval(x, allTags) {
						shouldBuild = false
					}
				}
			}
		}

		ext := nameExt(name)
		if !shouldBuild || tf.ignoreFile() {
			if ext == ".go" {
				p.IgnoredGoFiles = append(p.IgnoredGoFiles, name)
			} else if fileListForExt(p, ext) != nil {
				p.IgnoredOtherFiles = append(p.IgnoredOtherFiles, name)
			}
			continue
		}

// even though it only considers text until the first non-comment
// for +build lines.
//
// getFileInfo will return errNonSource if the file is not a source or object
// file and shouldn't even be added to IgnoredFiles.
func getFileInfo(dir, name string, fset *token.FileSet) (*fileInfo, error) {
	if strings.HasPrefix(name, "_") ||
		strings.HasPrefix(name, ".") {
		return nil, nil
	}

	i := strings.LastIndex(name, ".")