code: func (m *Meta) registerSynthConfigSource(filename string, src []byte) {
  	loader, err := m.initConfigLoader()
  	if err != nil || loader == nil {
  		return // treated as no-op, since this is best-effort
  	}
  	loader.Parser().ForceFileSource(filename, src)
  }
docs: // registerSynthConfigSource allows commands to add synthetic additional source
  // buffers to the config loader's cache of sources (as returned by
  // configSources), which is useful when a command is directly parsing something
  // from the command line that may produce diagnostics, so that diagnostic
  // snippets can still be produced.
  //
  // If this is called before a configLoader has been initialized then it will
  // try to initialize the loader but ignore any initialization failure, turning
  // the call into a no-op. (We presume that a caller will later call a different
  // function that also initializes the config loader as a side effect, at which
  // point those errors can be returned.)