pkg go/types, method (*Builtin) Pos() token.Pos
pkg go/types, method (*Builtin) String() string
pkg go/types, method (*Builtin) Type() Type
pkg go/types, method (*Chan) Dir() ChanDir
pkg go/types, method (*Chan) Elem() Type
pkg go/types, method (*Chan) String() string
pkg go/types, method (*Chan) Underlying() Type
pkg go/types, method (*Checker) Files([]*ast.File) error

pkg math/rand, func Read([]uint8) (int, error)
pkg math/rand, method (*Rand) Read([]uint8) (int, error)
pkg net, type DNSError struct, IsTemporary bool
pkg net, type Dialer struct, Cancel <-chan struct
pkg net/http, const MethodConnect = "CONNECT"
pkg net/http, const MethodConnect ideal-string
pkg net/http, const MethodDelete = "DELETE"
pkg net/http, const MethodDelete ideal-string

says `go` `1.20`, then the program defaults to `panicnil=1`,
matching Go 1.20 instead of Go 1.21.

Because this method of setting GODEBUG defaults was introduced only in Go 1.21,
programs listing versions of Go earlier than Go 1.20 are configured to match Go 1.20,
not the older version.

To override these defaults, a main package's source files
can include one or more `//go:debug` directives at the top of the file

pkg context, type CancelFunc func()
pkg context, type Context interface { Deadline, Done, Err, Value }
pkg context, type Context interface, Deadline() (time.Time, bool)
pkg context, type Context interface, Done() <-chan struct
pkg context, type Context interface, Err() error
pkg context, type Context interface, Value(interface{}) interface{}
pkg context, var Canceled error
pkg context, var DeadlineExceeded error