var golang.org/x/tools/internal/gocommand.modFlagRegexp

2 uses

	golang.org/x/tools/internal/gocommand (current package)
		vendor.go#L35: var modFlagRegexp = regexp.MustCompile(`-mod[ =](\w+)`)
		vendor.go#L55: 	matches := modFlagRegexp.FindStringSubmatch(goflags)