bpo-43795: Remove Py_FrozenMain from the Limited API & Stable ABI (GH-26241)

Py_FrozenMain was added to the Limited C API in [bpo-42591]() (3.10.0a4);
but to fix that issue it would be enough to add it to the regular C API.

The function is undocumented, tests were added very recently ([bpo-44131]()),
and most importantly, it is not present in all builds of Python, as
the linker sometimes omits it as unused.
It should be added back when these issues are fixed.

Note that this does not affect Python's regular C API.

Author: encukou

Doc/data/stable_abi.dat

@@ -783,7 +783,6 @@ var,Py_FileSystemDefaultEncodeErrors,3.10,
 var,Py_FileSystemDefaultEncoding,3.2,
 function,Py_Finalize,3.2,
 function,Py_FinalizeEx,3.6,
-function,Py_FrozenMain,3.10,
 function,Py_GenericAlias,3.9,
 function,Py_GenericAliasType,3.9,
 function,Py_GetBuildInfo,3.2,

Doc/whatsnew/3.10.rst

@@ -1927,6 +1927,10 @@ Porting to Python 3.10
   instead.
   (Contributed by Victor Stinner and Erlend E. Aasland in :issue:`43908`.)
 
+* The undocumented function ``Py_FrozenMain`` has been removed from the
+  limited API. The function is mainly useful for custom builds of Python.
+  (Contributed by Petr Viktorin in :issue:`26241`)
+
 Deprecated
 ----------
 

Include/cpython/pylifecycle.h

@@ -2,6 +2,10 @@
 #  error "this header file must not be included directly"
 #endif
 
+/* Py_FrozenMain is kept out of the Limited API until documented and present
+   in all builds of Python */
+PyAPI_FUNC(int) Py_FrozenMain(int argc, char **argv);
+
 /* Only used by applications that embed the interpreter and need to
  * override the standard encoding determination mechanism
  */

Include/pylifecycle.h

@@ -31,9 +31,6 @@ PyAPI_FUNC(void) _Py_NO_RETURN Py_Exit(int);
 
 /* Bootstrap __main__ (defined in Modules/main.c) */
 PyAPI_FUNC(int) Py_Main(int argc, wchar_t **argv);
-
-PyAPI_FUNC(int) Py_FrozenMain(int argc, char **argv);
-
 PyAPI_FUNC(int) Py_BytesMain(int argc, char **argv);
 
 /* In pathconfig.c */

Misc/NEWS.d/next/C API/2021-05-19-15-09-47.bpo-43795.WAHRxt.rst

@@ -0,0 +1 @@
+The undocumented function :c:func:`Py_FrozenMain` is removed from the Limited API.

Misc/stable_abi.txt

@@ -2079,8 +2079,6 @@ function PyType_GetModule
     added 3.10
 function PyType_GetModuleState
     added 3.10
-function Py_FrozenMain
-    added 3.10
 function PyFrame_GetLineNumber
     added 3.10
 function PyFrame_GetCode

PC/python3dll.c

@@ -55,7 +55,6 @@ EXPORT_FUNC(Py_Exit)
 EXPORT_FUNC(Py_FatalError)
 EXPORT_FUNC(Py_Finalize)
 EXPORT_FUNC(Py_FinalizeEx)
-EXPORT_FUNC(Py_FrozenMain)
 EXPORT_FUNC(Py_GenericAlias)
 EXPORT_FUNC(Py_GenericAliasType)
 EXPORT_FUNC(Py_GetArgcArgv)