Fix panic in TryFindUnderlyingTypeScanPlan

Check if CanConvert before calling reflect.Value.Convert

pgtype/pgtype.go

@@ -561,7 +561,7 @@ func TryFindUnderlyingTypeScanPlan(dst any) (plan WrappedScanPlanNextSetter, nex
 			}
 		}
 
-		if nextDstType != nil && dstValue.Type() != nextDstType {
+		if nextDstType != nil && dstValue.Type() != nextDstType && dstValue.CanConvert(nextDstType) {
 			return &underlyingTypeScanPlan{dstType: dstValue.Type(), nextDstType: nextDstType}, dstValue.Convert(nextDstType).Interface(), true
 		}
 

pgtype/pgtype_test.go

@@ -35,6 +35,7 @@ func init() {
 // Test for renamed types
 type _string string
 type _bool bool
+type _uint8 uint8
 type _int8 int8
 type _int16 int16
 type _int16Slice []int16
@@ -453,6 +454,14 @@ func TestMapScanNullToWrongType(t *testing.T) {
 	assert.False(t, pn.Valid)
 }
 
+func TestScanToSliceOfRenamedUint8(t *testing.T) {
+	m := pgtype.NewMap()
+	var ruint8 []_uint8
+	err := m.Scan(pgtype.Int2ArrayOID, pgx.TextFormatCode, []byte("{2,4}"), &ruint8)
+	assert.NoError(t, err)
+	assert.Equal(t, []_uint8{2, 4}, ruint8)
+}
+
 func TestMapScanTextToBool(t *testing.T) {
 	tests := []struct {
 		name string