// which are used to report a version error if allowVersion returns false.
func (check *Checker) verifyVersionf(at poser, v goVersion, format string, args ...interface{}) bool {
	if !check.allowVersion(at, v) {
		check.versionErrorf(at, v, format, args...)
		return false
	}
	return true

		var reverse bool
		if T != nil && sig.tparams != nil {
			if !versionErr && !check.allowVersion(instErrPos, go1_21) {
				if inst != nil {
					check.versionErrorf(instErrPos, go1_21, "partially instantiated function in assignment")
				} else {
					check.versionErrorf(instErrPos, go1_21, "implicitly instantiated function in assignment")
				}
			}
			gsig := NewSignatureType(nil, nil, nil, sig.params, sig.results, sig.variadic)

		var reverse bool
		if T != nil && sig.tparams != nil {
			if !versionErr && !check.allowVersion(instErrPos, go1_21) {
				if ix != nil {
					check.versionErrorf(instErrPos, go1_21, "partially instantiated function in assignment")
				} else {
					check.versionErrorf(instErrPos, go1_21, "implicitly instantiated function in assignment")
				}
			}
			gsig := NewSignatureType(nil, nil, nil, sig.params, sig.results, sig.variadic)

			if Identical(s.Elem(), a.Elem()) {
				if check == nil || check.allowVersion(x, go1_20) {
					return true
				}
				// check != nil
				if cause != nil {
					// TODO(gri) consider restructuring versionErrorf so we can use it here and below
					*cause = "conversion of slice to array requires go1.20 or later"
				}
				return false
			}
		case *Pointer:
			if a, _ := under(a.Elem()).(*Array); a != nil {

			if Identical(s.Elem(), a.Elem()) {
				if check == nil || check.allowVersion(x, go1_20) {
					return true
				}
				// check != nil
				if cause != nil {
					// TODO(gri) consider restructuring versionErrorf so we can use it here and below
					*cause = "conversion of slice to array requires go1.20 or later"
				}
				return false
			}
		case *Pointer:
			if a, _ := under(a.Elem()).(*Array); a != nil {

	}
	// len(s) > 2
	if strings.Contains(s, "_") {
		check.versionErrorf(lit, go1_13, "underscore in numeric literal")
		return
	}
	if s[0] != '0' {
		return
	}
	radix := s[1]
	if radix == 'b' || radix == 'B' {
		check.versionErrorf(lit, go1_13, "binary literal")
		return
	}
	if radix == 'o' || radix == 'O' {
		check.versionErrorf(lit, go1_13, "0o/0O-style octal literal")
		return
	}

	}
	// len(s) > 2
	if strings.Contains(s, "_") {
		check.versionErrorf(lit, go1_13, "underscore in numeric literal")
		return
	}
	if s[0] != '0' {
		return
	}
	radix := s[1]
	if radix == 'b' || radix == 'B' {
		check.versionErrorf(lit, go1_13, "binary literal")
		return
	}
	if radix == 'o' || radix == 'O' {
		check.versionErrorf(lit, go1_13, "0o/0O-style octal literal")
		return
	}

		if err != nil {
			base.Fatalf("verifying %v", module.VersionError(mod, err))
		}
		err = hashZip(mod, zip, ziphash)
		if err != nil {
			base.Fatalf("verifying %v", module.VersionError(mod, err))
		}
		return
	}
	h := string(data)
	if !strings.HasPrefix(h, "h1:") {
		base.Fatalf("verifying %v", module.VersionError(mod, fmt.Errorf("unexpected ziphash: %q", h)))
	}

// A ModuleError indicates an error specific to a module.
type ModuleError struct {
	Path    string
	Version string
	Err     error
}

// VersionError returns a [ModuleError] derived from a [Version] and error,
// or err itself if it is already such an error.
func VersionError(v Version, err error) error {
	var mErr *ModuleError
	if errors.As(err, &mErr) && mErr.Path == v.Path && mErr.Version == v.Version {
		return err
	}

				} else {
					err = fmt.Errorf("replacement directory %s: %w", r.Path, err)
				}
				return dir, true, module.VersionError(mod, err)
			}
			return dir, true, nil
		}
		mod = r
	}

	if mustHaveSums() && !modfetch.HaveSum(mod) {
		return "", false, module.VersionError(mod, &sumMissingError{})
	}

	dir, err = modfetch.Download(ctx, mod)
	return dir, false, err
}