Fix bug that caused error in type inference when returning from if (#427)

@weinbe58 @Roger-luo I'm still not 100% certain what the issue was, but
this fixes #402 .

I think it's because using the `frame` instead of creating a new one
meant it still had the function as `node` rather than the actual
`IfElse` statement. So we do need to create a new one here. Is that
correct?

Please take a look and let me know whether that explanation is correct,
I'd like to take this opportunity to learn ;)

Author: david-pl

src/kirin/dialects/scf/absint.py

@@ -62,4 +62,10 @@ def _infer_if_else_cond(
         if isinstance(body_term, func.Return):
             frame.worklist.append(interp.Successor(body_block, frame.get(stmt.cond)))
             return
-        return interp_.frame_call_region(frame, stmt, body, frame.get(stmt.cond))
+
+        with interp_.new_frame(stmt, has_parent_access=True) as body_frame:
+            ret = interp_.frame_call_region(
+                body_frame, stmt, body, frame.get(stmt.cond)
+            )
+            frame.entries.update(body_frame.entries)
+            return ret

test/analysis/dataflow/typeinfer/test_inter_method.py

@@ -10,12 +10,12 @@ def foo(x: int):
         return x - 1.0
 
 
-@basic(typeinfer=True)
+@basic(typeinfer=True, no_raise=False)
 def main(x: int):
     return foo(x)
 
 
-@basic(typeinfer=True)
+@basic(typeinfer=True, no_raise=False)
 def moo(x):
     return foo(x)
 
@@ -28,3 +28,18 @@ def test_inter_method_infer():
     assert foo.arg_types[0] == types.Int
     assert foo.inferred is False
     assert foo.return_type is types.Any
+
+
+def test_infer_if_return():
+    from kirin.prelude import structural
+
+    @structural(typeinfer=True, fold=True, no_raise=False)
+    def test(b: bool):
+        if b:
+            return False
+        else:
+            b = not b
+
+        return b
+
+    test.print()