cmd/compile/internal/types2: remove tparamIsIface flag and corresponding dead code

Added/clarified some comments.

Change-Id: Ib08d3343ff08c23cc8880a27a0148d1ff077a80f
Reviewed-on: https://go-review.googlesource.com/c/go/+/363654
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>

1 files changed, 2 insertions, 16 deletions

diff --git a/src/cmd/compile/internal/types2/predicates.go b/src/cmd/compile/internal/types2/predicates.go
index 62db3861ed..8ba534ce77 100644
--- a/src/cmd/compile/internal/types2/predicates.go
+++ b/src/cmd/compile/internal/types2/predicates.go
@@ -131,13 +131,7 @@ func comparable(T Type, seen map[Type]bool) bool {
 	case *Array:
 		return comparable(t.elem, seen)
 	case *Interface:
-		if tparamIsIface && isTypeParam(T) {
-			return t.IsComparable()
-		}
-		return true
-	case *TypeParam:
-		assert(!tparamIsIface)
-		return t.iface().IsComparable()
+		return !isTypeParam(T) || t.IsComparable()
 	}
 	return false
 }
@@ -150,15 +144,7 @@ func hasNil(t Type) bool {
 	case *Slice, *Pointer, *Signature, *Map, *Chan:
 		return true
 	case *Interface:
-		if tparamIsIface && isTypeParam(t) {
-			return u.typeSet().underIs(func(u Type) bool {
-				return u != nil && hasNil(u)
-			})
-		}
-		return true
-	case *TypeParam:
-		assert(!tparamIsIface)
-		return u.underIs(func(u Type) bool {
+		return !isTypeParam(t) || u.typeSet().underIs(func(u Type) bool {
 			return u != nil && hasNil(u)
 		})
 	}