-->

## Introduction {#intro}

Go's emphasis on backwards compatibility is one of its key strengths.
There are, however, times when we cannot maintain complete compatibility.
If code depends on buggy (including insecure) behavior,
then fixing the bug will break that code.
New features can also have similar impacts:
enabling the HTTP/2 use by the HTTP client broke programs
connecting to servers with buggy HTTP/2 implementations.

	ErrFieldTooLong    = errors.New("archive/tar: header field too long")
	ErrWriteAfterClose = errors.New("archive/tar: write after close")
	ErrInsecurePath    = errors.New("archive/tar: insecure file path")
	errMissData        = errors.New("archive/tar: sparse file references non-existent data")
	errUnrefData       = errors.New("archive/tar: sparse file contains unreferenced data")

			case *ast.TypeSpec:
				if isDeprecated(n.Doc) {
					mark(n.Name)
				}
				return true // recurse into struct or interface type
			case *ast.StructType:
				return true // recurse into fields
			case *ast.InterfaceType:
				return true // recurse into methods
			case *ast.FieldList:
				return true // recurse into fields
			case *ast.ValueSpec:
				if isDeprecated(n.Doc) {
					for _, id := range n.Names {