type DriverRequest … type DriverResponse … type driver … // findExternalDriver returns the file path of a tool that supplies // the build system package structure, or "" if not found. // If GOPACKAGESDRIVER is set in the environment findExternalTool returns its // value, otherwise it searches for a binary named gopackagesdriver on the PATH. func findExternalDriver(cfg *Config) driver { … } // slicesClip removes unused capacity from the slice, returning s[:len(s):len(s)]. // TODO(adonovan): use go1.21 slices.Clip. func slicesClip[S ~[]E, E any](s S) S { … }