| cmd/go/internal/base | Package base defines shared basic pieces of the go command, in particular logging and the Command structure. |
| cmd/go/internal/cfg | Package cfg holds configuration shared by multiple parts of the go command. |
| cmd/go/internal/fsys | Package fsys implements a virtual file system that the go command uses to read source file trees. |
| cmd/go/internal/modfetch | |
| cmd/go/internal/str | Package str provides string manipulation utilities. |
| context | Package context defines the Context type, which carries deadlines, cancellation signals, and other request-scoped values across API boundaries and between processes. |
| golang.org/x/mod/module | Package module defines the module.Version type along with support code. |
| golang.org/x/mod/semver | Package semver implements comparison of semantic version strings. |
| os | Package os provides a platform-independent interface to operating system functionality. |
| path | Package path implements utility routines for manipulating slash-separated paths. |
| path/filepath | Package filepath implements utility routines for manipulating filename paths in a way compatible with the target operating system-defined file paths. |
| strings | Package strings implements simple functions to manipulate UTF-8 encoded strings. |