go/src/cmd/go/internal/cache/default.go

// Default returns the default cache to use.
// It never returns nil.
func Default() Cache { … }

var initDefaultCacheOnce …

const cacheREADME …

// initDefaultCache does the work of finding the default cache
// the first time Default is called.
func initDefaultCache() Cache { … }

var defaultDirOnce …

var defaultDir …

var defaultDirChanged …

var defaultDirErr …

// DefaultDir returns the effective GOCACHE setting.
// It returns "off" if the cache is disabled,
// and reports whether the effective value differs from GOCACHE.
func DefaultDir() (string, bool) { … }