| cmd/go/internal/base | Package base defines shared basic pieces of the go command, in particular logging and the Command structure. |
| cmd/go/internal/cache | Package cache implements a build artifact cache. |
| cmd/go/internal/cfg | Package cfg holds configuration shared by multiple parts of the go command. |
| cmd/go/internal/load | Package load loads packages. |
| cmd/go/internal/modload | |
| cmd/go/internal/work | |
| encoding/json | Package json implements encoding and decoding of JSON as defined in RFC 7159. |
| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| go/build | Package build gathers information about Go packages. |
| io/ioutil | Package ioutil implements some I/O utility functions. |
| os | Package os provides a platform-independent interface to operating system functionality. |
| path/filepath | Package filepath implements utility routines for manipulating filename paths in a way compatible with the target operating system-defined file paths. |
| runtime | Package runtime contains operations that interact with Go's runtime system, such as functions to control goroutines. |
| sort | Package sort provides primitives for sorting slices and user-defined collections. |
| strings | Package strings implements simple functions to manipulate UTF-8 encoded strings. |
| unicode/utf8 | Package utf8 implements functions and constants to support text encoded in UTF-8. |