vitessio/vitess · error

%w; %s

Error message

%w; %s

What it means

This is the continuation/second variant of the package-load error aggregation in loadPackage: once a first load error exists, subsequent errors are appended with %w; %s so the returned error wraps the whole chain and supports errors.Is/Unwrap. It carries the same meaning as error 1080 — the target package failed to load with multiple errors.

Source

Thrown at go/vt/vtctl/vtctldclient/codegen/main.go:314

	}, source)
	if err != nil {
		return nil, err
	}

	if len(pkgs) != 1 {
		return nil, errors.New("must specify exactly one package")
	}

	pkg := pkgs[0]
	if len(pkg.Errors) > 0 {
		var err error

		for _, e := range pkg.Errors {
			switch err {
			case nil:
				err = fmt.Errorf("errors loading package %s: %s", source, e.Error())
			default:
				err = fmt.Errorf("%w; %s", err, e.Error())
			}
		}

		return nil, err
	}

	return pkg, nil
}

func extractSourceInterface(pkg *packages.Package, name string) (*types.Interface, error) {
	obj := pkg.Types.Scope().Lookup(name)
	if obj == nil {
		return nil, fmt.Errorf("no symbol found with name %s", name)
	}

	switch t := obj.Type().(type) {
	case *types.Named:
		iface, ok := t.Underlying().(*types.Interface)

View on GitHub (pinned to 01a25a7d17)

Solutions

1. Read the joined sub-errors after '; %s' — fix each underlying compile/import error it lists
2. Run 'go vet' or 'go build' on the package to see errors with file positions
3. Run 'go mod tidy' and re-run the codegen tool

Example fix

// before
$ go run ./go/vt/vtctl/vtctldclient/codegen
// errors loading package X: undefined: Foo; could not import bar
// after
$ go mod tidy && go build ./path/to/X && go run ./go/vt/vtctl/vtctldclient/codegen

// Fail fast on the first underlying load error before aggregation
pkgs, err := packages.Load(cfg, pattern)
if err != nil { return err }
for _, e := range pkgs[0].Errors {
    log.Printf("load error: %v", e)
}

When it happens

Trigger: Same as 1080: packages.Load returns pkg with len(pkg.Errors) > 0 and more than one load error, so the loop takes the default branch appending each error to the accumulated one.

Common situations: A package with several broken imports or multiple files with compile errors; vendored dependency missing causing cascading unresolved-import errors during vtctldclient codegen.

Related errors

• errors loading package %s: %s
• package '%s' does not contain 'ast_format.go'
• failed to process type %s: %w
• generator failed for type %s: %w
• unsupported pointer type %T

AI-assisted analysis of vitessio/vitess@01a25a7d17 (2026-09-01). Data as JSON: /api/errors/04101c2e7ccb2881. Report an issue: GitHub.