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py: Fix with+for+return bug by popping for-iter when unwinding exc stack.

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Addresses issue #1182.
This commit is contained in:
Damien George 2015-10-15 17:48:28 +01:00
parent 556c8a9a4f
commit 4bf3f2d3c0
3 changed files with 110 additions and 9 deletions
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23
py/vm.c
View File

@ -637,10 +637,14 @@ unwind_jump:;
unum -= 1;
assert(exc_sp >= exc_stack);
if (MP_TAGPTR_TAG1(exc_sp->val_sp)) {
// Getting here the stack looks like:
// (..., X, dest_ip)
// where X is pointed to by exc_sp->val_sp and in the case
// of a "with" block contains the context manager info.
// We're going to run "finally" code as a coroutine
// (not calling it recursively). Set up a sentinel
// on a stack so it can return back to us when it is
// done (when END_FINALLY reached).
// done (when WITH_CLEANUP or END_FINALLY reached).
PUSH((void*)unum); // push number of exception handlers left to unwind
PUSH(MP_OBJ_NEW_SMALL_INT(UNWIND_JUMP)); // push sentinel
ip = exc_sp->handler; // get exception handler byte code address
@ -1016,15 +1020,24 @@ unwind_jump:;
unwind_return:
while (exc_sp >= exc_stack) {
if (MP_TAGPTR_TAG1(exc_sp->val_sp)) {
// Getting here the stack looks like:
// (..., X, [iter0, iter1, ...,] ret_val)
// where X is pointed to by exc_sp->val_sp and in the case
// of a "with" block contains the context manager info.
// There may be 0 or more for-iterators between X and the
// return value, and these must be removed before control can
// pass to the finally code. We simply copy the ret_value down
// over these iterators, if they exist. If they don't then the
// following is a null operation.
mp_obj_t *finally_sp = MP_TAGPTR_PTR(exc_sp->val_sp);
finally_sp[1] = sp[0];
sp = &finally_sp[1];
// We're going to run "finally" code as a coroutine
// (not calling it recursively). Set up a sentinel
// on a stack so it can return back to us when it is
// done (when END_FINALLY reached).
// done (when WITH_CLEANUP or END_FINALLY reached).
PUSH(MP_OBJ_NEW_SMALL_INT(UNWIND_RETURN));
ip = exc_sp->handler;
// We don't need to do anything with sp, finally is just
// syntactic sugar for sequential execution??
// sp =
exc_sp--;
goto dispatch_loop;
}

49
tests/basics/try_finally_return.py
View File

@ -21,3 +21,52 @@ def func3():
print("finally 3")
print(func3())
# for loop within try-finally
def f():
try:
for i in [1, 2]:
return i
finally:
print('finally')
print(f())
# multiple for loops within try-finally
def f():
try:
for i in [1, 2]:
for j in [3, 4]:
return (i, j)
finally:
print('finally')
print(f())
# multiple for loops and nested try-finally's
def f():
try:
for i in [1, 2]:
for j in [3, 4]:
try:
for k in [5, 6]:
for l in [7, 8]:
return (i, j, k, l)
finally:
print('finally 2')
finally:
print('finally 1')
print(f())
# multiple for loops that are optimised, and nested try-finally's
def f():
try:
for i in range(1, 3):
for j in range(3, 5):
try:
for k in range(5, 7):
for l in range(7, 9):
return (i, j, k, l)
finally:
print('finally 2')
finally:
print('finally 1')
print(f())

47
tests/basics/with_return.py
View File

@ -1,14 +1,53 @@
class CtxMgr:
def __init__(self, id):
self.id = id
def __enter__(self):
print("__enter__")
print("__enter__", self.id)
return self
def __exit__(self, a, b, c):
print("__exit__", repr(a), repr(b))
print("__exit__", self.id, repr(a), repr(b))
# simple case
def foo():
with CtxMgr():
with CtxMgr(1):
return 4
print(foo())
# for loop within with (iterator needs removing upon return)
def f():
with CtxMgr(1):
for i in [1, 2]:
return i
print(f())
# multiple for loops within with
def f():
with CtxMgr(1):
for i in [1, 2]:
for j in [3, 4]:
return (i, j)
print(f())
# multiple for loops within nested withs
def f():
with CtxMgr(1):
for i in [1, 2]:
for j in [3, 4]:
with CtxMgr(2):
for k in [5, 6]:
for l in [7, 8]:
return (i, j, k, l)
print(f())
# multiple for loops that are optimised, and nested withs
def f():
with CtxMgr(1):
for i in range(1, 3):
for j in range(3, 5):
with CtxMgr(2):
for k in range(5, 7):
for l in range(7, 9):
return (i, j, k, l)
print(f())