go/src/cmd/compile/internal/types/goversion.go

type lang …

var langWant …

// AllowsGoVersion reports whether local package is allowed
// to use Go version major.minor.
func AllowsGoVersion(major, minor int) bool { … }

// ParseLangFlag verifies that the -lang flag holds a valid value, and
// exits if not. It initializes data used by AllowsGoVersion.
func ParseLangFlag() { … }

// parseLang parses a -lang option into a langVer.
func parseLang(s string) (lang, error) { … }

// currentLang returns the current language version.
func currentLang() string { … }

var goVersionRE …