code: func (m *Meta) loadBackendConfig(rootDir string) (*configs.Backend, tfdiags.Diagnostics) {
  	mod, diags := m.loadSingleModule(rootDir)
  	if diags.HasErrors() {
  		return nil, diags
  	}
  	return mod.Backend, diags
  }
docs: // loadBackendConfig reads configuration from the given directory and returns
  // the backend configuration defined by that module, if any. Nil is returned
  // if the specified module does not have an explicit backend configuration.
  //
  // This is a convenience method for command code that will delegate to the
  // configured backend to do most of its work, since in that case it is the
  // backend that will do the full configuration load.
  //
  // Although this method returns only the backend configuration, at present it
  // actually loads and validates the entire configuration first. Therefore errors
  // returned may be about other aspects of the configuration. This behavior may
  // change in future, so callers must not rely on it. (That is, they must expect
  // that a call to loadSingleModule or loadConfig could fail on the same
  // directory even if loadBackendConfig succeeded.)