vitessio/vitess · error

package '%s' does not contain 'ast_format.go'

Error message

package '%s' does not contain 'ast_format.go'

What it means

NewRewriter in the astfmtgen code-generation tool loads the target package, extracts the Expr interface, and requires the package to contain a file literally named ast_format.go; if none of the package's Go files has that base name it returns this error. The tool needs that file because the generated walker/writer code is keyed to it.

Source

Thrown at go/tools/astfmtgen/main.go:90

	}
}

type Rewriter struct {
	pkg     *packages.Package
	astExpr *types.Interface
	astfmt  int
}

var printerConfig = printer.Config{Mode: printer.UseSpaces | printer.TabIndent, Tabwidth: 8}

func NewRewriter(pkg *packages.Package) (*Rewriter, error) {
	scope := pkg.Types.Scope()
	exprT := scope.Lookup("Expr").(*types.TypeName)
	exprN := exprT.Type().(*types.Named).Underlying()

	astfmt := slices.IndexFunc(pkg.GoFiles, func(f string) bool { return path.Base(f) == "ast_format.go" })
	if astfmt < 0 {
		return nil, fmt.Errorf("package '%s' does not contain 'ast_format.go'", pkg.Name)
	}

	return &Rewriter{
		pkg:     pkg,
		astExpr: exprN.(*types.Interface),
		astfmt:  astfmt,
	}, nil
}

func (r *Rewriter) Rewrite() error {
	file := r.pkg.GoFiles[r.astfmt]
	syntax := r.pkg.Syntax[r.astfmt]

	// Add fmt import since %d is handled by calling fmt.Sprintf("%d",...)
	astutil.AddImport(r.pkg.Fset, syntax, "fmt")
	astutil.Apply(syntax, r.replaceAstfmtCalls, nil)

	dirname, _ := path.Split(file)

View on GitHub (pinned to 01a25a7d17)

Solutions

1. Invoke the tool on the correct package (go/vt/sqlparser), which contains ast_format.go
2. Restore/rename the file to ast_format.go if a refactor changed its name
3. Check pkg.GoFiles in the error context to confirm which package was actually loaded

Example fix

// before
astfmtgen -i vitess.io/vitess/go/vt/sqlparser/ast_clone_pkg // no ast_format.go
// after
astfmtgen -i vitess.io/vitess/go/vt/sqlparser // contains ast_format.go

func packageHasAstFormat(dir string) bool {
	_, err := os.Stat(filepath.Join(dir, "ast_format.go"))
	return err == nil
}

rw, err := NewRewriter(pkgPath)
if err != nil {
	if strings.Contains(err.Error(), "does not contain 'ast_format.go'") {
		return fmt.Errorf("wrong package for astfmtgen: %w", err)
	}
	return err
}

When it happens

Trigger: Running astfmtgen against a package directory whose sources lack ast_format.go (wrong package path argument, or a package that was restructured/renamed its format file).

Common situations: Passing go/vt/sqlparser-adjacent packages by mistake; refactors renaming ast_format.go; running the tool on a freshly scaffolded package that never had the file.

Related errors

• bad literal argument
• '%n' directive requires a slice
• slow path for `n` directive for slice of type other than Exp
• unsupported escape %q
• generator failed for type %s: %w

AI-assisted analysis of vitessio/vitess@01a25a7d17 (2026-09-01). Data as JSON: /api/errors/445af34284955e22. Report an issue: GitHub.