vm: Save current active exception on opening new try block.

Required to reraise correct exceptions in except block, regardless if more
try blocks with active exceptions happen in the same except block.

P.S. This "automagic reraise" appears to be quite wasteful feature of Python
- we need to save pending exception just in case it *might* be reraised.
Instead, programmer could explcitly capture exception to a variable using
"except ... as var", and reraise that. So, consider disabling argless raise
support as an optimization.

1 files changed, 23 insertions, 0 deletions

diff --git a/tests/basics/try-reraise2.py b/tests/basics/try-reraise2.py
new file mode 100644
index 0000000000..9ab8d9c099
--- /dev/null
+++ b/tests/basics/try-reraise2.py
@@ -0,0 +1,23 @@
+# Reraise not the latest occured exception
+def f():
+    try:
+        raise ValueError("val", 3)
+    except:
+        try:
+            raise TypeError
+        except:
+            try:
+                try:
+                    raise AttributeError
+                except:
+                    pass
+                raise
+            except TypeError:
+                pass
+        # This should raise original ValueError, not the most recently occurred AttributeError
+        raise
+
+try:
+    f()
+except ValueError as e:
+    print(repr(e))