internal/pkgbits: better documentation

Change-Id: I3f96a6e8a43faa5c8111b9d979aa37822c1dce06
Reviewed-on: https://go-review.googlesource.com/c/go/+/407434
Reviewed-by: Robert Griesemer <gri@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/src/cmd/compile/internal/noder/writer.go b/src/cmd/compile/internal/noder/writer.go
index 772a9e27c8..298ed493f7 100644
--- a/src/cmd/compile/internal/noder/writer.go
+++ b/src/cmd/compile/internal/noder/writer.go
@@ -109,11 +109,20 @@ type writerDict struct {
 	itabs []itabInfo
 }
 
+// A derivedInfo represents a reference to an encoded generic Go type.
 type derivedInfo struct {
 	idx    int
 	needed bool
 }
 
+// A typeInfo represents a reference to an encoded Go type.
+//
+// If derived is true, then the typeInfo represents a generic Go type
+// that contains type parameters. In this case, idx is an index into
+// the readerDict.derived{,Types} arrays.
+//
+// Otherwise, the typeInfo represents a non-generic Go type, and idx
+// is an index into the reader.typs array instead.
 type typeInfo struct {
 	idx     int
 	derived bool