bpo-45582: Port getpath[p].c to Python (GH-29041)

The getpath.py file is frozen at build time and executed as code over a namespace. It is never imported, nor is it meant to be importable or reusable. However, it should be easier to read, modify, and patch than the previous code.

This commit attempts to preserve every previously tested quirk, but these may be changed in the future to better align platforms.

1 files changed, 28 insertions, 13 deletions

diff --git a/Doc/c-api/init_config.rst b/Doc/c-api/init_config.rst
index 3642a8b..7c8fb7b 100644
--- a/Doc/c-api/init_config.rst
+++ b/Doc/c-api/init_config.rst
@@ -479,6 +479,9 @@ PyConfig
 
       Fields which are already initialized are left unchanged.
 
+      Fields for :ref:`path configuration <init-path-config>` are no longer
+      calculated or modified when calling this function, as of Python 3.11.
+
       The :c:func:`PyConfig_Read` function only parses
       :c:member:`PyConfig.argv` arguments once: :c:member:`PyConfig.parse_argv`
       is set to ``2`` after arguments are parsed. Since Python arguments are
@@ -493,6 +496,12 @@ PyConfig
          parsed, and arguments are only parsed if
          :c:member:`PyConfig.parse_argv` equals ``1``.
 
+      .. versionchanged:: 3.11
+         :c:func:`PyConfig_Read` no longer calculates all paths, and so fields
+         listed under :ref:`Python Path Configuration <init-path-config>` may
+         no longer be updated until :c:func:`Py_InitializeFromConfig` is
+         called.
+
    .. c:function:: void PyConfig_Clear(PyConfig *config)
 
       Release configuration memory.
@@ -848,12 +857,19 @@ PyConfig
 
       Default: value of the ``PLATLIBDIR`` macro which is set by the
       :option:`configure --with-platlibdir option <--with-platlibdir>`
-      (default: ``"lib"``).
+      (default: ``"lib"``, or ``"DLLs"`` on Windows).
 
       Part of the :ref:`Python Path Configuration <init-path-config>` input.
 
       .. versionadded:: 3.9
 
+      .. versionchanged:: 3.11
+         This macro is now used on Windows to locate the standard
+         library extension modules, typically under ``DLLs``. However,
+         for compatibility, note that this value is ignored for any
+         non-standard layouts, including in-tree builds and virtual
+         environments.
+
    .. c:member:: wchar_t* pythonpath_env
 
       Module search paths (:data:`sys.path`) as a string separated by ``DELIM``
@@ -870,9 +886,9 @@ PyConfig
 
       Module search paths: :data:`sys.path`.
 
-      If :c:member:`~PyConfig.module_search_paths_set` is equal to 0, the
-      function calculating the :ref:`Python Path Configuration <init-path-config>`
-      overrides the :c:member:`~PyConfig.module_search_paths` and sets
+      If :c:member:`~PyConfig.module_search_paths_set` is equal to 0,
+      :c:func:`Py_InitializeFromConfig` will replace
+      :c:member:`~PyConfig.module_search_paths` and sets
       :c:member:`~PyConfig.module_search_paths_set` to ``1``.
 
       Default: empty list (``module_search_paths``) and ``0``
@@ -944,16 +960,16 @@ PyConfig
 
    .. c:member:: int pathconfig_warnings
 
-      On Unix, if non-zero, calculating the :ref:`Python Path Configuration
-      <init-path-config>` can log warnings into ``stderr``. If equals to 0,
-      suppress these warnings.
-
-      It has no effect on Windows.
+      If non-zero, calculation of path configuration is allowed to log
+      warnings into ``stderr``. If equals to 0, suppress these warnings.
 
       Default: ``1`` in Python mode, ``0`` in isolated mode.
 
       Part of the :ref:`Python Path Configuration <init-path-config>` input.
 
+      .. versionchanged:: 3.11
+         Now also applies on Windows.
+
    .. c:member:: wchar_t* prefix
 
       The site-specific directory prefix where the platform independent Python
@@ -1305,10 +1321,9 @@ variables, command line arguments (:c:member:`PyConfig.argv` is not parsed)
 and user site directory. The C standard streams (ex: ``stdout``) and the
 LC_CTYPE locale are left unchanged. Signal handlers are not installed.
 
-Configuration files are still used with this configuration. Set the
-:ref:`Python Path Configuration <init-path-config>` ("output fields") to ignore these
-configuration files and avoid the function computing the default path
-configuration.
+Configuration files are still used with this configuration to determine
+paths that are unspecified. Ensure :c:member:`PyConfig.home` is specified
+to avoid computing the default path configuration.
 
 
 .. _init-python-config: