| go/ast | Package ast declares the types used to represent syntax trees for Go packages. |
| go/token | Package token defines constants representing the lexical tokens of the Go programming language and basic operations on tokens (printing, predicates). |
| go/types | Package types declares the data types and implements the algorithms for type-checking of Go packages. |
| golang.org/x/tools/go/analysis | Package analysis defines the interface between a modular static analysis and an analysis driver program. |
| golang.org/x/tools/internal/analysisinternal | Package analysisinternal provides gopls' internal analyses with a number of helper functions that operate on typed syntax trees. |
| os | Package os provides a platform-independent interface to operating system functionality. |