py/vm: Fix handling of unwind jump out of active finally.

Prior to this commit, when unwinding through an active finally the stack
was not being correctly popped/folded, which resulting in the VM crashing
for complicated unwinding of nested finallys.

This should be fixed with this commit, and more tests for return/break/
continue within a finally have been added to exercise this.

4 files changed, 62 insertions, 0 deletions

diff --git a/tests/basics/try_finally_break2.py b/tests/basics/try_finally_break2.py
new file mode 100644
index 000000000..086e92e90
--- /dev/null
+++ b/tests/basics/try_finally_break2.py
@@ -0,0 +1,19 @@
+def foo(x):
+    for i in range(x):
+        for j in range(x):
+            try:
+                print(x, i, j, 1)
+            finally:
+                try:
+                    try:
+                        print(x, i, j, 2)
+                    finally:
+                        try:
+                            1 / 0
+                        finally:
+                            print(x, i, j, 3)
+                            break
+                finally:
+                    print(x, i, j, 4)
+                    break
+print(foo(4))
diff --git a/tests/basics/try_finally_continue.py b/tests/basics/try_finally_continue.py
new file mode 100644
index 000000000..50040e5de
--- /dev/null
+++ b/tests/basics/try_finally_continue.py
@@ -0,0 +1,17 @@
+def foo(x):
+    for i in range(x):
+        try:
+            pass
+        finally:
+            try:
+                try:
+                    print(x, i)
+                finally:
+                    try:
+                        1 / 0
+                    finally:
+                        return 42
+            finally:
+                print('continue')
+                continue
+print(foo(4))
diff --git a/tests/basics/try_finally_continue.py.exp b/tests/basics/try_finally_continue.py.exp
new file mode 100644
index 000000000..2901997b1
--- /dev/null
+++ b/tests/basics/try_finally_continue.py.exp
@@ -0,0 +1,9 @@
+4 0
+continue
+4 1
+continue
+4 2
+continue
+4 3
+continue
+None
diff --git a/tests/basics/try_finally_return5.py b/tests/basics/try_finally_return5.py
new file mode 100644
index 000000000..aa2327e65
--- /dev/null
+++ b/tests/basics/try_finally_return5.py
@@ -0,0 +1,17 @@
+def foo(x):
+    for i in range(x):
+        try:
+            pass
+        finally:
+            try:
+                try:
+                    print(x, i)
+                finally:
+                    try:
+                        1 / 0
+                    finally:
+                        return 42
+            finally:
+                print('return')
+                return 43
+print(foo(4))