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GeezerVison is showing github.com — bpo-42282: Fold constants inside named expressions by ncoghlan · Pull Request #23190 · python/cpython

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@ncoghlan

@ncoghlan ncoghlan commented Nov 7, 2020 •
edited by bedevere-bot
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  • The AST optimiser wasn't descending into named expressions, so
    any constant subexpressions weren't being folded at compile time
  • Remove "default:" clauses inside the AST optimiser code to reduce the
    risk of similar bugs passing unnoticed in future compiler changes

https://bugs.python.org/issue42282

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@ncoghlan
bpo-42282: Fold constants inside named expressions
6ca7c28
* The AST optimiser wasn't descending into named expressions, so
  any constant subexpressions weren't being folded at compile time
* Remove "default:" clauses inside the AST optimiser code to reduce the
  risk of similar bugs passing unnoticed in future compiler changes
@ncoghlan
ncoghlan requested a review from brandtbucher November 7, 2020 11:09
@the-knights-who-say-ni the-knights-who-say-ni added the CLA signed label Nov 7, 2020
@bedevere-bot bedevere-bot added the awaiting core review label Nov 7, 2020
@ncoghlan

ncoghlan commented Nov 7, 2020

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@brandtbucher I noticed this omission while working on PEP 642.

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@ncoghlan
ncoghlan requested a review from methane November 7, 2020 11:11
methane
methane approved these changes Nov 7, 2020
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LGTM

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@bedevere-bot bedevere-bot added awaiting merge and removed awaiting core review labels Nov 7, 2020
ncoghlan added 2 commits November 7, 2020 21:44
@ncoghlan
Fix inverted comparison op folding
45e3d50
@ncoghlan
Fix comment
3addcc9
@ncoghlan

ncoghlan commented Nov 7, 2020

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The CI failures were due to one of the switch statements using an int rather than an AST enum type, so the compiler didn't know there were unhandled cases after I dropped the default: clause. I switched it to using cmpop_ty and added the missing cases.

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ncoghlan added 2 commits November 7, 2020 22:04
@ncoghlan
Still clear errors that occur in constant folding
f8e52c0
@ncoghlan
Minor code tweak (need to trigger new CI run anyway)
a4741aa
@ncoghlan

ncoghlan commented Nov 7, 2020

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There was a second set of CI failures due to a regression in binary operator folding (it wasn't clearing divide-by-zero errors), but the failure after that was just a GitHub Actions glitch (I have the tests passing locally now - I hadn't checked that before the first push).

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@ncoghlan
ncoghlan merged commit 8805a4d into python:master Nov 7, 2020
@bedevere-bot bedevere-bot removed the awaiting merge label Nov 7, 2020
shihai1991 added a commit to shihai1991/cpython that referenced this pull request Nov 7, 2020
@shihai1991
Merge remote-tracking branch 'origin/master' into bpo_41073_add_types…
2d72953
…lots1

* origin/master: (80 commits)
  bpo-42282: Fold constants inside named expressions (pythonGH-23190)
  bpo-41028: Doc: Move switchers to docsbuild-scripts. (pythonGH-20969)
  bpo-42133: update parts of the stdlib to fall back to `__spec__.loader` when `__loader__` is missing (python#22929)
  Remove outdated reference to pywin32 from platform module (pythonGH-22005)
  bpo-41832: PyType_FromModuleAndSpec() now accepts NULL tp_doc (pythonGH-23123)
  Minor grammar edits for the descriptor howto guide (GH-python#23175)
  bpo-42179: Doc/tutorial: Remove mention of __cause__ (pythonGH-23162)
  bpo-26389: Allow passing an exception object in the traceback module (pythonGH-22610)
  bpo-42260: PyConfig_Read() only parses argv once (pythonGH-23168)
  bpo-42260: Add _PyConfig_FromDict() (pythonGH-23167)
  bpo-41877 Check for asert, aseert, assrt in mocks (pythonGH-23165)
  [docs] fix wrongly named AsyncContextDecorator (pythonGH-23164)
  bpo-42262: Add Py_NewRef() and Py_XNewRef() (pythonGH-23152)
  bpo-42266: Handle monkey-patching descriptors in LOAD_ATTR cache (pythonGH-23157)
  bpo-40816 Add AsyncContextDecorator class (pythonGH-20516)
  bpo-42260: Add _PyInterpreterState_SetConfig() (pythonGH-23158)
  Disable peg generator tests when building with PGO (pythonGH-23141)
  bpo-1635741: _sqlite3 uses PyModule_AddObjectRef() (pythonGH-23148)
  bpo-1635741: Fix PyInit_pyexpat() error handling (pythonGH-22489)
  bpo-42260: Main init modify sys.flags in-place (pythonGH-23150)
  ...
adorilson pushed a commit to adorilson/cpython that referenced this pull request Mar 13, 2021
@ncoghlan @adorilson
bpo-42282: Fold constants inside named expressions (pythonGH-23190)
e2ff8e0
* The AST optimiser wasn't descending into named expressions, so
  any constant subexpressions weren't being folded at compile time
* Remove "default:" clauses inside the AST optimiser code to reduce the
  risk of similar bugs passing unnoticed in future compiler changes
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@methane methane methane approved these changes
@brandtbucher brandtbucher Awaiting requested review from brandtbucher

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4 participants

@ncoghlan @methane @the-knights-who-say-ni @bedevere-bot
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