fix jackc#2204

pgtype/json.go

@@ -161,6 +161,10 @@ func (c *JSONCodec) PlanScan(m *Map, oid uint32, format int16, target any) ScanP
 //
 // https://github.com/jackc/pgx/issues/2146
 func isSQLScanner(v any) bool {
+	if _, is := v.(sql.Scanner); is {
+		return true
+	}
+
 	val := reflect.ValueOf(v)
 	for val.Kind() == reflect.Ptr {
 		if _, ok := val.Interface().(sql.Scanner); ok {
@@ -212,6 +216,11 @@ func (s *scanPlanJSONToJSONUnmarshal) Scan(src []byte, dst any) error {
 		return fmt.Errorf("cannot scan NULL into %T", dst)
 	}
 
+	v := reflect.ValueOf(dst)
+	if v.Kind() != reflect.Pointer || v.IsNil() {
+		return fmt.Errorf("cannot scan into non-pointer or nil destinations %T", dst)
+	}
+
 	elem := reflect.ValueOf(dst).Elem()
 	elem.Set(reflect.Zero(elem.Type()))
 

pgtype/json_test.go

@@ -267,7 +267,8 @@ func TestJSONCodecCustomMarshal(t *testing.T) {
 				Unmarshal: func(data []byte, v any) error {
 					return json.Unmarshal([]byte(`{"custom":"value"}`), v)
 				},
-			}})
+			},
+		})
 	}
 
 	pgxtest.RunValueRoundTripTests(context.Background(), t, connTestRunner, pgxtest.KnownOIDQueryExecModes, "json", []pgxtest.ValueRoundTripTest{
@@ -278,3 +279,20 @@ func TestJSONCodecCustomMarshal(t *testing.T) {
 		}},
 	})
 }
+
+func TestJSONCodecScanToNonPointerValues(t *testing.T) {
+	defaultConnTestRunner.RunTest(context.Background(), t, func(ctx context.Context, t testing.TB, conn *pgx.Conn) {
+		n := 44
+		err := conn.QueryRow(ctx, "select '42'::jsonb").Scan(n)
+		require.Error(t, err)
+
+		var i *int
+		err = conn.QueryRow(ctx, "select '42'::jsonb").Scan(i)
+		require.Error(t, err)
+
+		m := 0
+		err = conn.QueryRow(ctx, "select '42'::jsonb").Scan(&m)
+		require.NoError(t, err)
+		require.Equal(t, 42, m)
+	})
+}

pgtype/pgtype.go

@@ -415,6 +415,10 @@ func (plan *scanPlanSQLScanner) Scan(src []byte, dst any) error {
 
 // we don't know if the target is a sql.Scanner or a pointer on a sql.Scanner, so we need to check recursively
 func getSQLScanner(target any) sql.Scanner {
+	if sc, is := target.(sql.Scanner); is {
+		return sc
+	}
+
 	val := reflect.ValueOf(target)
 	for val.Kind() == reflect.Ptr {
 		if _, ok := val.Interface().(sql.Scanner); ok {