gh-142349: Implement PEP 810 - Explicit lazy imports#142351

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pablogsal merged 169 commits into

python:mainfrom

LazyImportsCabal:lazy

Feb 12, 2026

Commits on Oct 2, 2025

Lazy imports grammar / AST changes
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Add __lazy_import__, check sys.modules before import
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Export lazy_import in imp module
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Add lazy import filter
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Add compatiblity mode
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Flow import func through to lazy imports object and __lazy_import__
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Reify lazy objects when accessed via the module object
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Import lazy.get
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Implement better error

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Fix reference and global dict in spezializing LOAD_GLOBAL

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Remove copyright

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More fixes

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Fix recursive lazy imports and error path in bytecodes.c

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fix offset in addr2line

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Add global flag

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Draft: force * imports to be eager

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Syntax restrictions for lazy imports

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Fix submodules crash

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Implement disabling imports in try/except and * imports, report errors on bad usage of lazy
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Add PyExc_ImportCycleError and raise it when a cycle is detected
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Publish lazy imported packages on parent
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Re-enable eagerly returning imported module
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Fix __lazy_modules__

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Add sys.set_lazy_imports_filter

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Simplify grammar

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Move __lazy_imports__ check into the interpreter
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Don't allow __lazy_imports__ to work in try/except
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Make imports in with blocks syntax errors
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Commits on Oct 3, 2025

Highlight lazy imports in the new REPL
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Merge pull request #2 from bswck/lazy-import-pyrepl-highlight
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Commits on Oct 7, 2025

Fix global membership in LOAD_NAME
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C was a mistake
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dir() doesn't reify module
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Merge pull request #7 from LazyImportsCabal/lazy_dir
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Add test case for external usage
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Move eager check for from imports into import from
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Commits on Oct 8, 2025

Merge pull request #8 from LazyImportsCabal/lazy_test
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Expose LazyImportType in types module
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__import__ is loaded at reification time
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Fix leaks and LOAD_ATTR specialization
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Merge pull request #9 from LazyImportsCabal/cleanup
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Commits on Oct 9, 2025

Update sys module to conform with the PEP, add matching C API
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Merge pull request #10 from LazyImportsCabal/sys_c_api
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Commits on Oct 20, 2025

Fix specialization of load global
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Merge pull request #12 from DinoV/lazy_mt
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Commits on Oct 21, 2025

Fix bug in specialization and make reification atomic
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Fix another race
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Commits on Oct 22, 2025

Merge pull request #14 from LazyImportsCabal/fix
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Commits on Oct 23, 2025

Make __dict__ not reify to match the PEP
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Allow try/except in with block
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Commits on Oct 24, 2025

Merge pull request #16 from LazyImportsCabal/lazy_globals
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Commits on Oct 25, 2025

Grab builtins dict from module
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Merge pull request #17 from DinoV/lazy_builtins
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Fix eager imports in try/except in global mode
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Merge pull request #18 from LazyImportsCabal/bad_global
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Don't reify on REPL completion
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Commits on Oct 27, 2025

Add tests for __lazy_import__
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Commits on Nov 3, 2025

Merge remote-tracking branch 'origin/main' into HEAD
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Commits on Nov 5, 2025

Merge pull request #21 from LazyImportsCabal/lazy_rebase
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Commits on Nov 9, 2025

Merge pull request #19 from DinoV/lazy_tests_dunder
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Commits on Dec 6, 2025

Implement more of PEP 810
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Add more tests
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Add more tests
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Merge remote-tracking branch 'upstream/main' into lazy
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Regen stuff
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Ah yes....windows
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More windows stuff and news
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Updated versions
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Update Doc/whatsnew/3.15.rst
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Add support in IDLE colorizer
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Merge pull request #22 from StanFromIreland/lazy-idle
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Address feedback
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Fix tests
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Update Doc/whatsnew/3.15.rst
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Ruff fixes
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JIT fixes
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Fix smelly
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Fix smelly
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Fix repl not coloring 'lazy' after 'from'
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Doc fixes
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brrrrrrrrrrrrrrrrrrrrrr
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Merge pull request #24 from StanFromIreland/lazy-color
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Amend return types for `PyImport_SetLazy*` functions
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moar fixes much refleaks wow
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Merge pull request #25 from picnixz/patch-1
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Doc updates
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Make error for invalid `lazy from __future__ ...` import prettier
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Regen limited ABI
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Merge branch 'lazy' into lazy-future-error
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Fix error paths and edge cases
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Free threading fixes
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TSAN fixes
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Update magic number
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Merge pull request #26 from StanFromIreland/lazy-future-error
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Regen frozenmain
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Fix WASI failure
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Commits on Dec 7, 2025

document return value for `PyImport_GetLazyImportsFilter`

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fix error path in `_PyImport_LoadLazyImportTstate`

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fix UAFs in `register_lazy_on_parent`

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fix error path in `_PyImport_LazyImportModuleLevelObject`

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fix error path in `_imp__set_lazy_attributes_impl`

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Various UAFs & cosmetic fixes in `Python/{bltinmodule,bytecode,ceval}.c` (#33)
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Fix missing `lazy`-related symbols for the JIT (#34)
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Merge branch 'main' into lazy
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Commits on Dec 8, 2025

Fix and improve `Objects/lazyimportobject.c` (#31)
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Fix doc merge snafu.
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Fix examples in the `ast` module docs (run by doctest).
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Don't include the new C API functions
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Add the new builtin types to the known-to-be-mutable-global lists in
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Fix some crashes
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Document ImportCycleError and PyExc_ImportCycleError.
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Use `self.assertIn/assertNotIn` instead of `self.assertTrue/assertFalse` (#27)
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Fix more cases where lazy is not highlighted in repl (#36)
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Commits on Dec 10, 2025

Merge branch 'main' of github.com:python/cpython into lazy_head
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Make sys.lazy_modules reflect the internal structure currently in use
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More thread safety fixes
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_PyLazyImport_New improvements
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Add lazy import dis tests
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Add C API tests
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Make comment clearer
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Fixup clinic issue
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Commits on Dec 11, 2025

Merge branch 'main' of github.com:python/cpython into HEAD
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Remove tsan fixes pending https://github.com/colesbury/cpython/tree/gh-142534-consume
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Commits on Dec 15, 2025

Standardize versionadded tags and minor updates to documentation
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Combine two very similar sentences together.
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Address open comments
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Commits on Dec 16, 2025

Apply PEP-7 to `Python/import.c` (#29)
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Commits on Dec 17, 2025

Reflow and reformat to stick to PEP 7's line length limit in most places,
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Merge branch 'main' into lazy
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Merge pull request #38 from Yhg1s/reflow-reformat
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Do not reify in tracebacks
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Merge branch 'main' into lazy
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Fix comment about `check_lazy_import_compatibility` (#39)
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Commits on Dec 18, 2025

Update Doc/library/sys.rst
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Regen generated files.
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Remove get_lazy_modules from docs
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Get rid of a merge snafu.
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Remove cruft from module object left over from reification of __dict__
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Fixup lazy import object, don't allow subclassing, improve doc, and variable names in lazy_import_new
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Merge pull request #40 from hugovk/3.15-lazy-rm-get_lazy_modules
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Commits on Dec 19, 2025

Add test exercising that the appropriate error is raised when calling
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Commits on Jan 4, 2026

Merge branch 'main' into lazy
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Commits on Jan 5, 2026

Fix test_sys after the removal of m_dict_version from the module object in
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Address Abby's docs comment.
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Remove `types.LazyImportType` from pure variant of `types` (#48)
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Commits on Jan 15, 2026

Merge branch 'main' of github.com:python/cpython into lazy_review_updates
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Commits on Jan 26, 2026

Fix ups from code reviews
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Use dictionary watchers to update version number on writes to dictionary
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Commits on Jan 27, 2026

Small fixups
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Merge pull request #49 from DinoV/lazy_review_updates
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Flow _PyInterpreterFrame into _PyLazyImport_New
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Fix test/test_types
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Commits on Jan 28, 2026

Add include for jit stencils
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Merge branch 'main' of github.com:python/cpython into lazy_review_updates2
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Fix free threaded build
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Merge pull request #50 from DinoV/lazy_review_updates2
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Merge branch 'main' into lazy
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Fix bad merge
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Merge pull request #51 from DinoV/fix_merge
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Commits on Feb 11, 2026

Merge branch 'main' of github.com:python/cpython into HEAD
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Merge pull request #52 from DinoV/lazy_merge
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Merge branch 'main' into lazy
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