async def syntax should be rejected if python version < 3.5 #2401
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Michael0x2a
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Jun 12, 2017
Python 3.5 introduced three new forms of syntax: - Coroutines with async/await (PEP 492) - The '@' operator (PEP 465) - Additional unpacking generalizations (PEP 448) This commit adds a version check for the first two, but not the last item. This commit was originally motivated by python/mypy#2401. I decided to also add a check for '@' because it looked like an easy fix, but didn't add a check for the unpacking generalizations because that seemed harder.
ddfisher
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Jun 13, 2017
…#41) Python 3.5 introduced three new forms of syntax: - Coroutines with async/await (PEP 492) - The '@' operator (PEP 465) - Additional unpacking generalizations (PEP 448) This commit adds a version check for the first two, but not the last item. This commit was originally motivated by python/mypy#2401. I decided to also add a check for the '@' operator because it looked like an easy fix, but didn't add a check for the unpacking generalizations because that seemed harder. The checks for `async for`, `async with`, and `await` are probably unnecessary because they can only be used inside `async def` anyways, which will always be checked first, but I figured I might as well add them just in case. I can remove them if you want, though, since it probably does incur a slight performance hit.
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This issue should be fixed by python/typed_ast#41 (assuming that typed_ast publishes a new release and mypy updates its requirements info before it also releases, etc). FWIW, after making this change, I wasn't able to trigger the crash by making Awaitable and friends conditional. That said, I also didn't test this very thoroughly, so take that with a grain of salt. |
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This already works correctly. |
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Code using
async defshould not be allowed to type-check when a Python version less than 3.5 is selected.Moreover, there are several types in typeshed that should only be defined for Python versions >= 3.5, e.g. Awaitable; but if I make those conditional in typeshed/stdlib/3/typing.pyi, mypy actually crashes on
async deffunctions.The text was updated successfully, but these errors were encountered: