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base repository: python/cpython
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head repository: eendebakpt/cpython
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compare: feature/clinic-parser-split
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  • 1 commit
  • 48 files changed
  • 2 contributors

Commits on Sep 13, 2026

  1. gh-136681: Shrink _PyArg_Parser and skip its init for static kwtuples 

    Move the fields only used by parsers with a format string (format,
custom_msg, min, max) into a new _PyArg_ParserExt structure, referenced
by _PyArg_Parser.ext.  Argument Clinic emits it only for the few
functions parsed with _PyArg_ParseStackAndKeywords(); the ~750 parsers
using _PyArg_UnpackKeywords() leave ext NULL.  With is_kwtuple_owned
narrowed to uint8_t, _PyArg_Parser shrinks from 72 to 48 bytes on 64-bit
platforms.

Argument Clinic now also stores the number of positional-only
parameters (pos) statically.  _PyArg_UnpackKeywords() therefore skips
parser_init() when the keyword tuple is statically allocated (builtin
modules): such parsers are never written to at run time, and are no
longer registered for cleanup at finalization.  Lazily built keyword
tuples are published with _Py_atomic_store_ptr_release() after all
other fields are set.

_parser_init() accepts a statically set pos (checked against the
keyword list), and parser_clear() keeps it, since it only depends on
the keywords.  The PyErr_BadInternalCall() checks in the internal
_PyArg_UnpackKeywords() become assertions.  c-analyzer is taught about
the new _PyArg_ParserExt static variables.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
    @eendebakpt @claude
    eendebakpt and claude committed Sep 13, 2026
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