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py: Handle case of return within the finally block of try-finally.
Addresses issue adafruit#1636.
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‎py/vm.c‎

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Original file line numberDiff line numberDiff line change
@@ -1032,6 +1032,14 @@ unwind_jump:;
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ENTRY(MP_BC_RETURN_VALUE):
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MARK_EXC_IP_SELECTIVE();
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// These next 3 lines pop a try-finally exception handler, if one
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// is there on the exception stack. Without this the finally block
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// is executed a second time when the return is executed, because
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// the try-finally exception handler is still on the stack.
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// TODO Possibly find a better way to handle this case.
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if (currently_in_except_block) {
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POP_EXC_BLOCK();
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}
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unwind_return:
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while (exc_sp >= exc_stack) {
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if (MP_TAGPTR_TAG1(exc_sp->val_sp)) {

‎tests/basics/try_finally_return2.py‎

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@@ -0,0 +1,104 @@
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# test 'return' within the finally block
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# it should swallow the exception
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# simple case
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def f():
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try:
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raise ValueError()
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finally:
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print('finally')
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return 0
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print('got here')
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print(f())
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# nested, return in outer
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def f():
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try:
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try:
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raise ValueError
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finally:
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print('finally 1')
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print('got here')
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finally:
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print('finally 2')
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return 2
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print('got here')
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print(f())
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# nested, return in inner
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def f():
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try:
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try:
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raise ValueError
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finally:
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print('finally 1')
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return 1
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print('got here')
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finally:
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print('finally 2')
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print('got here')
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print(f())
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# nested, return in inner and outer
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def f():
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try:
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try:
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raise ValueError
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finally:
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print('finally 1')
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return 1
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print('got here')
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finally:
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print('finally 2')
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return 2
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print('got here')
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print(f())
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# nested with reraise
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def f():
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try:
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try:
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raise ValueError
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except:
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raise
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print('got here')
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finally:
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print('finally')
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return 0
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print('got here')
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print(f())
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# triple nesting with reraise
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def f():
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try:
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try:
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try:
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raise ValueError
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except:
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raise
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except:
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raise
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finally:
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print('finally')
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return 0
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print(f())
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# exception when matching exception
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def f():
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try:
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raise ValueError
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except NonExistingError:
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pass
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finally:
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print('finally')
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return 0
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print(f())
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# raising exception class, not instance
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def f():
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try:
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raise ValueError
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finally:
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print('finally')
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return 0
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print(f())

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