error_(token.NoPos, "unexpected type %T in walk", x)
	panic("unexpected type")
}

func funcTypeTypeParams(n *ast.FuncType) *ast.FieldList {
	return nil
}

func typeSpecTypeParams(n *ast.TypeSpec) *ast.FieldList {
	return nil

	case *ast.IndexListExpr:
		f.walk(&n.X, ctxExpr, visit)
		f.walk(n.Indices, ctxExpr, visit)
	}
}

func funcTypeTypeParams(n *ast.FuncType) *ast.FieldList {
	return n.TypeParams
}

func typeSpecTypeParams(n *ast.TypeSpec) *ast.FieldList {
	return n.TypeParams

		if len(n.Names) == 2 && len(n.Values) == 1 {
			f.walk(&n.Values[0], ctxAssign2, visit)
		} else {
			f.walk(n.Values, ctxExpr, visit)
		}
	case *ast.TypeSpec:
		if tparams := typeSpecTypeParams(n); tparams != nil {
			f.walk(tparams, ctxParam, visit)
		}
		f.walk(&n.Type, ctxType, visit)

	case *ast.BadDecl:
	case *ast.GenDecl:
		f.walk(n.Specs, ctxSpec, visit)
	case *ast.FuncDecl: