cmd/compile/internal/types2: use []*TypeParam rather than []*TypeName for type param lists

This is a port of CL 343932 from go/types, with the necessary adjustments
to the compiler.

This change improves type safety slightly, avoids many internal type
assertions, and simplifies some code paths.

Change-Id: Ie9c4734814f49cd248927152d7b3264d3578428c
Reviewed-on: https://go-review.googlesource.com/c/go/+/344614
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Dan Scales <danscales@google.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/src/cmd/compile/internal/types2/predicates.go b/src/cmd/compile/internal/types2/predicates.go
index 3c883e1ab5..ed62743f6d 100644
--- a/src/cmd/compile/internal/types2/predicates.go
+++ b/src/cmd/compile/internal/types2/predicates.go
@@ -349,13 +349,13 @@ func identical(x, y Type, cmpTags bool, p *ifacePair) bool {
 	return false
 }
 
-func identicalTParams(x, y []*TypeName, cmpTags bool, p *ifacePair) bool {
+func identicalTParams(x, y []*TypeParam, cmpTags bool, p *ifacePair) bool {
 	if len(x) != len(y) {
 		return false
 	}
 	for i, x := range x {
 		y := y[i]
-		if !identical(x.typ.(*TypeParam).bound, y.typ.(*TypeParam).bound, cmpTags, p) {
+		if !identical(x.bound, y.bound, cmpTags, p) {
 			return false
 		}
 	}