cmd/compile/internal/noder: document the PosBase section
Positions mostly borrow their representation from package syntax. Of
note, constants (such as the zero value for positions) are not encoded
directly. Rather, a flag typically signals such values.
Change-Id: I6b4bafc6e96bb21902dd2d6e164031e7dd5aabdd
Reviewed-on: https://go-review.googlesource.com/c/go/+/673535
TryBot-Bypass: Mark Freeman <mark@golang.org> Reviewed-by: Robert Griesemer <gri@google.com>
Auto-Submit: Mark Freeman <mark@golang.org>