Fix locals()/vars() cell-variable sync for module/class scope - #8467
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youknowone merged 1 commit intoAug 8, 2026
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…tside function scope CPython's _PyFrame_GetLocals only syncs fastlocals/cells into locals() for function scope; module/class scope just returns the namespace dict as-is. sync_visible_locals_to_mapping did this for every scope, so the implicit __conditional_annotations__ cell (used for PEP 649/749 deferred annotations) broke two ways: at module scope its cell is always empty, so syncing overwrote the dict's real value with None, causing NameError on the next annotated statement; at class scope its cell is the only real value, so syncing leaked it into locals()/dir(), unlike CPython. Skip cell/free slots outside function scope to match CPython, and add a regression snippet. Closes RustPython#8379 Assisted-by: Claude Code:claude-sonnet-5
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…tside function scope (RustPython#8467) CPython's _PyFrame_GetLocals only syncs fastlocals/cells into locals() for function scope; module/class scope just returns the namespace dict as-is. sync_visible_locals_to_mapping did this for every scope, so the implicit __conditional_annotations__ cell (used for PEP 649/749 deferred annotations) broke two ways: at module scope its cell is always empty, so syncing overwrote the dict's real value with None, causing NameError on the next annotated statement; at class scope its cell is the only real value, so syncing leaked it into locals()/dir(), unlike CPython. Skip cell/free slots outside function scope to match CPython, and add a regression snippet. Closes RustPython#8379 Assisted-by: Claude Code:claude-sonnet-5
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Summary
_PyFrame_GetLocalsonly syncs fastlocals/cells intolocals()for function scope; for module/class scope it just returns the namespace dict as-is, since ordinary names there are already stored viaStoreName, not fastlocals.sync_visible_locals_to_mappingdid the fastlocals/cell sync for every scope, so the implicit__conditional_annotations__cell (added for PEP 649/749 deferred annotations) broke two ways:1. At module scope its cell is always empty (real writes go through
StoreName), so syncing overwrote the dict's real value withNone, deleting it and causingNameErroron the next annotated statement.2. At class scope the cell is the only place the value lives (
StoreDeref-only, never in the dict), so syncing instead leaked__conditional_annotations__intolocals()/dir(), which CPython never does.Fix
Skip
CO_FAST_CELL/CO_FAST_FREEslots for non-optimized (module/class) scope insync_visible_locals_to_mapping, matching CPython's behavior.Details
v3.14.6tag): module codegen writes__conditional_annotations__withStoreNameinto the dict; class codegen writes it withStoreDerefinto the cell only._PyFrame_GetLocalsnever reads cells for either scope — it returns the namespace dict directly for non-optimized scope.CO_FAST_CELL/CO_FAST_FREE, notCO_FAST_HIDDEN— a hidden slot (PEP 709 inlined comprehensions) can also be a cell, and the existing hidden-variable check just above already decides per-slot whether a live hidden value should still appear inlocals(). Gating on scope alone would have overridden that.Testing
extra_tests/snippets/syntax_annotations_locals.py, covering both the module-scope corruption and the class-scope leak. Confirmed it fails with the pre-fixNameErroron unfixed code and passes after the fix.cargo test -p rustpython-codegen(783 tests),cargo test -p rustpython-vm --lib(55 tests): all pass.test_annotationlib(117/117),test_builtin(138/138),test_class(37/37) all pass.cargo clippy/cargo fmt --check: clean.AI assistance
Investigated, implemented, and tested with Claude Code assistance, including direct comparison against a local CPython 3.14.6 source checkout and binary; all findings and the fix were manually verified before submission.
Assisted-by: Claude Code:claude-sonnet-5
Summary by CodeRabbit
Bug Fixes
locals()behavior in module and class scopes to match Python semantics.exec.locals()ordir()results.Tests