fix: worklist pop should always pop first (#384)

This should fix the error in constprop.

cc: @kaihsin

Author: Roger-luo

src/kirin/worklist.py

@@ -26,5 +26,5 @@ def extend(self, items: Iterable[ElemType]) -> None:
 
     def pop(self) -> ElemType | None:
         if self._stack:
-            return self._stack.pop()
+            return self._stack.pop(0)
         return None

test/analysis/dataflow/constprop/test_worklist.py

@@ -0,0 +1,33 @@
+from kirin.prelude import basic_no_opt
+from kirin.analysis import const
+
+
+def test_worklist_bfs():
+    @basic_no_opt
+    def make_ker(val: float):
+
+        def ker(i: float):
+            return i + val
+
+        return ker
+
+    @basic_no_opt
+    def test(x: str, y: float, flag: bool):
+
+        if x == "x":
+            val = 1.0
+        else:
+            val = 2.0
+
+        if flag:
+            ker = make_ker(val=val)
+
+        else:
+            ker = make_ker(val=val)
+
+        return ker
+
+    # test.print()
+    prop = const.Propagate(basic_no_opt)
+    frame, ret = prop.run_analysis(test)
+    assert isinstance(ret, const.PartialLambda)