Don't flag intentionally empty generators unreachable by ikonst · Pull Request #15722 · python/mypy

ikonst · 2023-07-20T03:01:49Z

ikonst · 2023-07-20T03:02:05Z

sobolevn

Thanks for working on this!

AlexWaygood · 2023-07-20T18:22:56Z

 yield None
 self.inferred_attribute_types = old_types

+ def _is_empty_generator(self, func: FuncItem) -> bool:


Suggested change
def_is_empty_generator(self, func: FuncItem) ->bool:
@staticmethod
def_is_empty_generator(func: FuncItem) ->bool:
Or even better: move the function into the global scope?

AlexWaygood · 2023-07-20T18:23:35Z

 #
 # TODO: Find a way of working around this limitation
- if len(expanded) >= 2:
+ if len(expanded) >= 2 or self._is_empty_generator(item):


Maybe update the multiline comment immediately above this line? We're not just suppressing reachability warnings for TypeVars with value restrictions anymore

Yeah, I didn't want to muddy the blame for that comment 🤣

AlexWaygood

teeny tiny nits

AlexWaygood · 2023-07-20T18:41:54Z

+ return (
+ len(body := func.body.body) == 2


Nit: I think the first walrus here is slightly gratuitous
Suggested change
return (
len(body:=func.body.body) ==2
body=func.body.body
return (
len(body) ==2

AlexWaygood · 2023-07-20T18:44:25Z

+ # We suppress reachability warnings for empty generators (return; yield), since there's
+ # no way to promote a function into a generator except by adding an "unreachable" yield.


Suggested change
# We suppress reachability warnings for empty generators (return; yield), since there's
# no way to promote a function into a generator except by adding an "unreachable" yield.
# We also suppress reachability warnings for empty generator functions
# (return; yield), since the most idiomatic way to promote a function into a
# generator function is often to add an "unreachable" yield.

I had "also" at first, but I wanted to be able to remove the first comment w/o touching the second.

Meh, I think I'd personally prioritise a readable comment over a tiny bit more churn in git blame :p

Ahh, easy. I've just made the "TODO remove me" part second. :P

Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>

AlexWaygood

LGTM, thanks!

ikonst · 2023-07-23T03:16:11Z

@AlexWaygood I removed the comment in a090d56 since now this field appears to have a long-term legitimate use.

…_as_unreachable

Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>

github-actions · 2023-07-24T16:38:59Z

Diff from mypy_primer, showing the effect of this PR on open source code:

graphql-core (https://github.com/graphql-python/graphql-core): typechecking got 1.05x slower (366.9s -> 386.6s)
(Performance measurements are based on a single noisy sample)

hauntsaninja

Thankss!

Don't flag intentionally empty generators unreachable
05cfabd

add test
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asottile approved these changes Jul 20, 2023
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sobolevn reviewed Jul 20, 2023
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Comment threadtest-data/unit/check-unreachable-code.test

support 'return None' and 'yield None'
7871b8d

AlexWaygood reviewed Jul 20, 2023
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AlexWaygood feedback
5e33f47

ikonst force-pushed the 07-19-intentionally_empty_generator_marked_as_unreachable branch from e31efd3 to 5e33f47Compare July 20, 2023 18:39

AlexWaygood reviewed Jul 20, 2023
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less walrus
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make the TODO-remove part second
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AlexWaygood reviewed Jul 20, 2023
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Comment threadmypy/checker.py Outdated
Comment threadmypy/checker.py Outdated
Comment threadtest-data/unit/check-unreachable-code.test Outdated
Comment threadtest-data/unit/check-unreachable-code.test Outdated
Comment threadmypy/checker.py Outdated

ikonstand others added 2 commits July 20, 2023 17:53

empty generator *functions*
6d20704
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>

empty generator *function*
82e8c8c
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>

AlexWaygood reviewed Jul 20, 2023
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Update mypy/checker.py
2a95a6d
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>

AlexWaygood approved these changes Jul 20, 2023
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Remove TODO / comment around suppress_unreachable_warnings
a090d56

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Merge branch 'master' into 07-19-intentionally_empty_generator_marked…
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…_as_unreachable

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Update checker.py comment
7c2a83b

AlexWaygood reviewed Jul 24, 2023
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Comment threadmypy/checker.py Outdated

Update mypy/checker.py
df177cd
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>

hauntsaninja approved these changes Jul 26, 2023
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hauntsaninja merged commit 01c6994 into python:masterJul 26, 2023

ikonst deleted the 07-19-intentionally_empty_generator_marked_as_unreachable branch July 26, 2023 12:06

	def_is_empty_generator(self, func: FuncItem) ->bool:
	@staticmethod
	def_is_empty_generator(func: FuncItem) ->bool:

-return (
-len(body:=func.body.body) ==2
+body=func.body.body
+return (
+len(body) ==2

		# We suppress reachability warnings for empty generators (return; yield), since there's
		# no way to promote a function into a generator except by adding an "unreachable" yield.

-# We suppress reachability warnings for empty generators (return; yield), since there's
-# no way to promote a function into a generator except by adding an "unreachable" yield.
+# We also suppress reachability warnings for empty generator functions
+# (return; yield), since the most idiomatic way to promote a function into a
+# generator function is often to add an "unreachable" yield.

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ikonst commented Jul 20, 2023• edited Loading Uh oh! There was an error while loading. Please reload this page.

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ikonst commented Jul 23, 2023• edited Loading Uh oh! There was an error while loading. Please reload this page.

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github-actionsBot commented Jul 24, 2023

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ikonst commented Jul 20, 2023•
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ikonst commented Jul 23, 2023•
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