pkg go/types, method (*Named) Underlying() Type
pkg go/types, method (*Nil) Exported() bool
pkg go/types, method (*Nil) Id() string
pkg go/types, method (*Nil) Name() string
pkg go/types, method (*Nil) Parent() *Scope
pkg go/types, method (*Nil) Pkg() *Package
pkg go/types, method (*Nil) Pos() token.Pos
pkg go/types, method (*Nil) String() string
pkg go/types, method (*Nil) Type() Type
pkg go/types, method (*Package) Complete() bool

The [GODEBUG History](#history) gives the exact defaults for each Go toolchain version.
For example, Go 1.21 introduces the `panicnil` setting,
controlling whether `panic(nil)` is allowed;
it defaults to `panicnil=0`, making `panic(nil)` a run-time error.
Using `panicnil=1` restores the behavior of Go 1.20 and earlier.

When compiling a work module or workspace that declares