fix panic OpMinUntil return before restore repeat

Author: qingshi163

.vscode/launch.json

@@ -0,0 +1,21 @@
+{
+    "version": "0.2.0",
+    "configurations": [
+        {
+            "type": "lldb",
+            "request": "launch",
+            "name": "Debug Unit Test",
+            "cargo": {
+                "args": [
+                    "test",
+                    "--no-run"
+                ],
+                "filter": {
+                    "kind": "test"
+                }
+            },
+            "args": [],
+            "cwd": "${workspaceFolder}"
+        }
+    ]
+}

src/engine.rs

@@ -14,7 +14,7 @@ pub struct State<'a> {
     pub string: StrDrive<'a>,
     pub start: usize,
     pub end: usize,
-    flags: SreFlag,
+    _flags: SreFlag,
     pattern_codes: &'a [u32],
     pub marks: Vec<Option<usize>>,
     pub lastindex: isize,
@@ -42,7 +42,7 @@ impl<'a> State<'a> {
             string,
             start,
             end,
-            flags,
+            _flags: flags,
             pattern_codes,
             lastindex: -1,
             marks_stack: Vec::new(),
@@ -1380,16 +1380,18 @@ impl OpcodeExecutor for OpMinUntil {
                 None
             }
             2 => {
+                // restore repeat before return
+                drive.state.repeat_stack.push(self.save_repeat.unwrap());
+
                 let child_ctx = drive.state.popped_context.unwrap();
                 if child_ctx.has_matched == Some(true) {
                     drive.ctx_mut().has_matched = Some(true);
                     return None;
                 }
-                drive.state.repeat_stack.push(self.save_repeat.unwrap());
                 drive.state.string_position = drive.ctx().string_position;
                 drive.state.marks_pop();
 
-                // match more unital tail matches
+                // match more until tail matches
                 let RepeatContext {
                     count: _,
                     code_position,

tests/tests.rs

@@ -60,3 +60,14 @@ fn test_zerowidth() {
     state = state.search();
     assert!(state.string_position == 1);
 }
+
+#[test]
+fn test_repeat_context_panic() {
+    // pattern p = re.compile(r'(?:a*?(xx)??z)*')
+    // START GENERATED by generate_tests.py
+    #[rustfmt::skip] let p = Pattern { code: &[15, 4, 0, 0, 4294967295, 24, 25, 0, 4294967295, 27, 6, 0, 4294967295, 17, 97, 1, 24, 11, 0, 1, 18, 0, 17, 120, 17, 120, 18, 1, 20, 17, 122, 19, 1], flags: SreFlag::from_bits_truncate(32) };
+    // END GENERATED
+    let mut state = p.state("axxzaz", 0..usize::MAX);
+    state = state.pymatch();
+    assert!(state.marks == vec![Some(1), Some(3)]);
+}