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, 9 insertions, 9 deletions

diff --git a/src/cmd/compile/internal/types2/signature.go b/src/cmd/compile/internal/types2/signature.go
index e319e65211..f1bf60ae8e 100644
--- a/src/cmd/compile/internal/types2/signature.go
+++ b/src/cmd/compile/internal/types2/signature.go
@@ -57,13 +57,13 @@ func (s *Signature) Recv() *Var { return s.recv }
 func (s *Signature) TParams() *TParamList { return s.tparams }
 
 // SetTParams sets the type parameters of signature s.
-func (s *Signature) SetTParams(tparams []*TypeName) { s.tparams = bindTParams(tparams) }
+func (s *Signature) SetTParams(tparams []*TypeParam) { s.tparams = bindTParams(tparams) }
 
 // RParams returns the receiver type parameters of signature s, or nil.
 func (s *Signature) RParams() *TParamList { return s.rparams }
 
 // SetRParams sets the receiver type params of signature s.
-func (s *Signature) SetRParams(rparams []*TypeName) { s.rparams = bindTParams(rparams) }
+func (s *Signature) SetRParams(rparams []*TypeParam) { s.rparams = bindTParams(rparams) }
 
 // Params returns the parameters of signature s, or nil.
 func (s *Signature) Params() *Tuple { return s.params }
@@ -119,14 +119,14 @@ func (check *Checker) funcType(sig *Signature, recvPar *syntax.Field, tparams []
 				// blank identifiers were found => use rewritten receiver type
 				recvTyp = isubst(recvPar.Type, smap)
 			}
-			rlist := make([]*TypeName, len(rparams))
+			rlist := make([]*TypeParam, len(rparams))
 			for i, rparam := range rparams {
 				rlist[i] = check.declareTypeParam(rparam)
 			}
 			sig.rparams = bindTParams(rlist)
 			// determine receiver type to get its type parameters
 			// and the respective type parameter bounds
-			var recvTParams []*TypeName
+			var recvTParams []*TypeParam
 			if rname != nil {
 				// recv should be a Named type (otherwise an error is reported elsewhere)
 				// Also: Don't report an error via genericType since it will be reported
@@ -142,19 +142,19 @@ func (check *Checker) funcType(sig *Signature, recvPar *syntax.Field, tparams []
 				// We have a list of *TypeNames but we need a list of Types.
 				list := make([]Type, sig.RParams().Len())
 				for i, t := range sig.RParams().list() {
-					list[i] = t.typ
+					list[i] = t
 				}
 				smap := makeSubstMap(recvTParams, list)
-				for i, tname := range sig.RParams().list() {
-					bound := recvTParams[i].typ.(*TypeParam).bound
+				for i, tpar := range sig.RParams().list() {
+					bound := recvTParams[i].bound
 					// bound is (possibly) parameterized in the context of the
 					// receiver type declaration. Substitute parameters for the
 					// current context.
 					// TODO(gri) should we assume now that bounds always exist?
 					//           (no bound == empty interface)
 					if bound != nil {
-						bound = check.subst(tname.pos, bound, smap, nil)
-						tname.typ.(*TypeParam).bound = bound
+						bound = check.subst(tpar.obj.pos, bound, smap, nil)
+						tpar.bound = bound
 					}
 				}
 			}