cmd/compile/internal/types2: use a TypeList type to hold type arguments

This is a port of CL 343933 from go/types with the necessary
adjustments in the compiler.

With this CL type parameters and type lists are now held in
TParamList and TypeList data types which don't expose the
internal representation.

Change-Id: I6d60881b5db995dbc04ed3f4a96e8b5d41f83969
Reviewed-on: https://go-review.googlesource.com/c/go/+/344615
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Dan Scales <danscales@google.com>

1 files changed, 8 insertions, 8 deletions

diff --git a/src/cmd/compile/internal/noder/writer.go b/src/cmd/compile/internal/noder/writer.go
index 02df9a43de..a6bd8b2426 100644
--- a/src/cmd/compile/internal/noder/writer.go
+++ b/src/cmd/compile/internal/noder/writer.go
@@ -299,7 +299,7 @@ func (pw *pkgWriter) typIdx(typ types2.Type, dict *writerDict) typeInfo {
 		// Type aliases can refer to uninstantiated generic types, so we
 		// might see len(TParams) != 0 && len(TArgs) == 0 here.
 		// TODO(mdempsky): Revisit after #46477 is resolved.
-		assert(typ.TParams().Len() == len(typ.TArgs()) || len(typ.TArgs()) == 0)
+		assert(typ.TParams().Len() == typ.TArgs().Len() || typ.TArgs().Len() == 0)
 
 		// TODO(mdempsky): Why do we need to loop here?
 		orig := typ
@@ -441,10 +441,10 @@ func (w *writer) param(param *types2.Var) {
 
 // @@@ Objects
 
-func (w *writer) obj(obj types2.Object, explicits []types2.Type) {
-	explicitInfos := make([]typeInfo, len(explicits))
-	for i, explicit := range explicits {
-		explicitInfos[i] = w.p.typIdx(explicit, w.dict)
+func (w *writer) obj(obj types2.Object, explicits *types2.TypeList) {
+	explicitInfos := make([]typeInfo, explicits.Len())
+	for i := range explicitInfos {
+		explicitInfos[i] = w.p.typIdx(explicits.At(i), w.dict)
 	}
 	info := objInfo{idx: w.p.objIdx(obj), explicits: explicitInfos}
 
@@ -1212,7 +1212,7 @@ func (w *writer) expr(expr syntax.Expr) {
 	if obj != nil {
 		if isGlobal(obj) {
 			w.code(exprName)
-			w.obj(obj, targs)
+			w.obj(obj, types2.NewTypeList(targs))
 			return
 		}
 
@@ -1321,7 +1321,7 @@ func (w *writer) expr(expr syntax.Expr) {
 
 				// As if w.expr(expr.Fun), but using inf.TArgs instead.
 				w.code(exprName)
-				w.obj(obj, inf.TArgs)
+				w.obj(obj, types2.NewTypeList(inf.TArgs))
 			} else {
 				w.expr(expr.Fun)
 			}
@@ -1711,7 +1711,7 @@ func (w *writer) pkgDecl(decl syntax.Decl) {
 		// TODO(mdempsky): Revisit after #46477 is resolved.
 		if name.IsAlias() {
 			named, ok := name.Type().(*types2.Named)
-			if ok && named.TParams().Len() != 0 && len(named.TArgs()) == 0 {
+			if ok && named.TParams().Len() != 0 && named.TArgs().Len() == 0 {
 				break
 			}
 		}