From 05916ad360096dacb2d4fefc5acec646fe4c2d82 Mon Sep 17 00:00:00 2001
From: Aofei Sheng <aofei@aofeisheng.com>
Date: Tue, 11 Mar 2025 08:51:37 +0800
Subject: [PATCH] refactor: export `BoundTypeError` with `Fset` and `Pos`
 fields

Updates goplus/builder#1378

Signed-off-by: Aofei Sheng <aofei@aofeisheng.com>
---
 builtin_test.go |  2 +-
 template.go     | 14 ++++++++++----
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/builtin_test.go b/builtin_test.go
index 79533f5..95b27cd 100644
--- a/builtin_test.go
+++ b/builtin_test.go
@@ -837,7 +837,7 @@ func TestTypeEx(t *testing.T) {
 			typ.Underlying()
 		}()
 	}
-	bte := &boundTypeError{tyInt, TyByte}
+	bte := &BoundTypeError{Fset: pkg.cb.fset, a: tyInt, b: TyByte}
 	if bte.Error() != "boundType int => byte failed" {
 		t.Fatal("boundTypeError:", bte)
 	}
diff --git a/template.go b/template.go
index 04effb9..4246c12 100644
--- a/template.go
+++ b/template.go
@@ -98,15 +98,21 @@ func getElemTypeIf(t types.Type, parg *internal.Elem) types.Type {
 	return t
 }
 
-type boundTypeError struct {
+type BoundTypeError struct {
+	Fset dbgPositioner
+	Pos  token.Pos
 	a, b types.Type
 }
 
-func (p *boundTypeError) Error() string {
+func (p *BoundTypeError) Error() string {
 	return fmt.Sprintf("boundType %v => %v failed", p.a, p.b)
 }
 
 func boundType(pkg *Package, arg, param types.Type, parg *internal.Elem) error {
+	var pos token.Pos
+	if parg != nil && parg.Src != nil {
+		pos = parg.Src.Pos()
+	}
 	switch p := param.(type) {
 	case *unboundFuncParam: // template function param
 		if p.tBound == nil {
@@ -116,7 +122,7 @@ func boundType(pkg *Package, arg, param types.Type, parg *internal.Elem) error {
 			p.boundTo(pkg, arg, parg)
 		} else if !AssignableConv(pkg, getElemTypeIf(arg, parg), p.tBound, parg) {
 			if !(isUntyped(pkg, p.tBound) && AssignableConv(pkg, p.tBound, arg, p.parg)) {
-				return &boundTypeError{a: arg, b: p.tBound}
+				return &BoundTypeError{Fset: pkg.cb.fset, Pos: pos, a: arg, b: p.tBound}
 			}
 			p.tBound = arg
 		}
@@ -137,7 +143,7 @@ func boundType(pkg *Package, arg, param types.Type, parg *internal.Elem) error {
 		case *types.Map:
 			if t, ok := arg.(*types.Map); ok {
 				if err1 := boundType(pkg, t.Key(), param.Key(), nil); err1 != nil { // TODO: expr = nil
-					return &boundTypeError{a: t.Key(), b: param.Key()}
+					return &BoundTypeError{Fset: pkg.cb.fset, Pos: pos, a: t.Key(), b: param.Key()}
 				}
 				return boundType(pkg, t.Elem(), param.Elem(), nil) // TODO: expr = nil
 			}