From 0c7119464ec064e1fa16cc862f4d9f2ec8526a2f Mon Sep 17 00:00:00 2001
From: visualfc <visualfc@gmail.com>
Date: Fri, 26 Jan 2024 09:44:09 +0800
Subject: [PATCH] hide TyOverloadNamed to sig

---
 ast.go             |  7 ++++---
 func_ext.go        |  2 +-
 type_ext.go        | 25 ++++++++++++++++++++++++-
 typeparams.go      |  2 +-
 typeparams_test.go |  2 +-
 5 files changed, 31 insertions(+), 7 deletions(-)

diff --git a/ast.go b/ast.go
index 25fb356e..27a9a5ae 100644
--- a/ast.go
+++ b/ast.go
@@ -697,9 +697,10 @@ retry:
 	case *TyInstruction:
 		return t.instr.Call(pkg, args, flags, fn.Src)
 	case *TypeType: // type convert
-		return matchTypeCast(pkg, t.Type(), fn, args, flags)
-	case *TyOverloadNamed:
-		return matchOverloadNamedTypeCast(pkg, t.Obj, fn.Src, args, flags)
+		if on, ok := CheckOverloadNamed(t.typ); ok {
+			return matchOverloadNamedTypeCast(pkg, on.Obj, fn.Src, args, flags)
+		}
+		return matchTypeCast(pkg, t.typ, fn, args, flags)
 	case *types.Named:
 		fnType = pkg.cb.getUnderlying(t)
 		goto retry
diff --git a/func_ext.go b/func_ext.go
index 2f9fdbb2..a2267509 100644
--- a/func_ext.go
+++ b/func_ext.go
@@ -58,7 +58,7 @@ const (
 )
 
 // sigFuncEx return func type ($overloadArgs ...interface{$overloadMethod()})
-func sigFuncEx(pkg *types.Package, recv *types.Var, t TyFuncEx) *types.Signature {
+func sigFuncEx(pkg *types.Package, recv *types.Var, t types.Type) *types.Signature {
 	sig := types.NewSignatureType(types.NewVar(token.NoPos, nil, "", t), nil, nil, nil, nil, false)
 	typ := types.NewInterfaceType([]*types.Func{
 		types.NewFunc(token.NoPos, nil, overloadMethod, sig),
diff --git a/type_ext.go b/type_ext.go
index 2bcb1461..0eeaa35d 100644
--- a/type_ext.go
+++ b/type_ext.go
@@ -105,11 +105,34 @@ func (p *TyOverloadNamed) String() string {
 
 func NewOverloadNamed(pos token.Pos, pkg *types.Package, name string, typs ...*types.Named) *types.TypeName {
 	t := &TyOverloadNamed{Types: typs}
-	o := types.NewTypeName(pos, pkg, name, t)
+	sig := sigFuncEx(pkg, nil, t)
+	o := types.NewTypeName(pos, pkg, name, sig)
 	t.Obj = o
 	return o
 }
 
+// CheckOverloadNamed returns if specified type is a TyOverloadNamed or not.
+func CheckOverloadNamed(typ types.Type) (*TyOverloadNamed, bool) {
+	switch sig := typ.(type) {
+	case *TyOverloadNamed:
+		return sig, true
+	case *types.Signature:
+		if sig.Params().Len() == 1 {
+			if param := sig.Params().At(0); param.Name() == overloadArgs {
+				if typ, ok := param.Type().(*types.Interface); ok && typ.NumMethods() == 1 {
+					if sig, ok := typ.Method(0).Type().(*types.Signature); ok {
+						if recv := sig.Recv(); recv != nil {
+							t, ok := recv.Type().(*TyOverloadNamed)
+							return t, ok
+						}
+					}
+				}
+			}
+		}
+	}
+	return nil, false
+}
+
 type TyInstruction struct {
 	instr Instruction
 }
diff --git a/typeparams.go b/typeparams.go
index 39a3fab2..26cd0588 100644
--- a/typeparams.go
+++ b/typeparams.go
@@ -471,7 +471,7 @@ func (p *Package) Instantiate(orig types.Type, targs []types.Type, src ...ast.No
 		p.cb.ensureLoaded(targ)
 	}
 	ctxt := p.cb.ctxt
-	if on, ok := orig.(*TyOverloadNamed); ok {
+	if on, ok := CheckOverloadNamed(orig); ok {
 		var first error
 		for _, t := range on.Types {
 			ret, err := types.Instantiate(ctxt, t, targs, true)
diff --git a/typeparams_test.go b/typeparams_test.go
index 226cb6d3..69b56757 100644
--- a/typeparams_test.go
+++ b/typeparams_test.go
@@ -60,7 +60,7 @@ func Gopx_Var_Cast__1[T map[string]any]() *Var__1[T] {
 	scope := pkgRef.Types.Scope()
 	log.Println("==> Lookup", scope.Lookup("Var__0"))
 	objVar := pkgRef.Ref("Var")
-	on, ok := objVar.Type().(*gox.TyOverloadNamed)
+	on, ok := gox.CheckOverloadNamed(objVar.Type())
 	if !ok {
 		t.Fatal("TestOverloadNamed: not TyOverloadNamed?")
 	}