patch 9.0.1776: No support for stable Python 3 ABI Commit: https://github.com/vim/vim/commit/c13b3d1350b60b94fe87f0761ea31c0e7fb6ebf3 Author: Yee Cheng Chin <ychin.git@gmail.com> Date: Sun Aug 20 21:18:38 2023 +0200 patch 9.0.1776: No support for stable Python 3 ABI Problem: No support for stable Python 3 ABI Solution: Support Python 3 stable ABI Commits: 1) Support Python 3 stable ABI to allow mixed version interoperatbility Vim currently supports embedding Python for use with plugins, and the "dynamic" linking option allows the user to specify a locally installed version of Python by setting `pythonthreedll`. However, one caveat is that the Python 3 libs are not binary compatible across minor versions, and mixing versions can potentially be dangerous (e.g. let's say Vim was linked against the Python 3.10 SDK, but the user sets `pythonthreedll` to a 3.11 lib). Usually, nothing bad happens, but in theory this could lead to crashes, memory corruption, and other unpredictable behaviors. It's also difficult for the user to tell something is wrong because Vim has no way of reporting what Python 3 version Vim was linked with. For Vim installed via a package manager, this usually isn't an issue because all the dependencies would already be figured out. For prebuilt Vim binaries like MacVim (my motivation for working on this), AppImage, and Win32 installer this could potentially be an issue as usually a single binary is distributed. This is more tricky when a new Python version is released, as there's a chicken-and-egg issue with deciding what Python version to build against and hard to keep in sync when a new Python version just drops and we have a mix of users of different Python versions, and a user just blindly upgrading to a new Python could lead to bad interactions with Vim. Python 3 does have a solution for this problem: stable ABI / limited API (see https://docs.python.org/3/c-api/stable.html). The C SDK limits the API to a set of functions that are promised to be stable across versions. This pull request adds an ifdef config that allows us to turn it on when building Vim. Vim binaries built with this option should be safe to freely link with any Python 3 libraies without having the constraint of having to use the same minor version. Note: Python 2 has no such concept and this doesn't change how Python 2 integration works (not that there is going to be a new version of Python 2 that would cause compatibility issues in the future anyway). --- Technical details: ====== The stable ABI can be accessed when we compile with the Python 3 limited API (by defining `Py_LIMITED_API`). The Python 3 code (in `if_python3.c` and `if_py_both.h`) would now handle this and switch to limited API mode. Without it set, Vim will still use the full API as before so this is an opt-in change. The main difference is that `PyType_Object` is now an opaque struct that we can't directly create "static types" out of, and we have to create type objects as "heap types" instead. This is because the struct is not stable and changes from version to version (e.g. 3.8 added a `tp_vectorcall` field to it). I had to change all the types to be allocated on the heap instead with just a pointer to them. Other functions are also simply missing in limited API, or they are introduced too late (e.g. `PyUnicode_AsUTF8AndSize` in 3.10) to it that we need some other ways to do the same thing, so I had to abstract a few things into macros, and sometimes re-implement functions like `PyObject_NEW`. One caveat is that in limited API, `OutputType` (used for replacing `sys.stdout`) no longer inherits from `PyStdPrinter_Type` which I don't think has any real issue other than minor differences in how they convert to a string and missing a couple functions like `mode()` and `fileno()`. Also fixed an existing bug where `tp_basicsize` was set incorrectly for `BufferObject`, `TabListObject, `WinListObject`. Technically, there could be a small performance drop, there is a little more indirection with accessing type objects, and some APIs like `PyUnicode_AsUTF8AndSize` are missing, but in practice I didn't see any difference, and any well-written Python plugin should try to avoid excessing callbacks to the `vim` module in Python anyway. I only tested limited API mode down to Python 3.7, which seemes to compile and work fine. I haven't tried earlier Python versions. 2) Fix PyIter_Check on older Python vers / type##Ptr unused warning For PyIter_Check, older versions exposed them as either macros (used in full API), or a function (for use in limited API). A previous change exposed PyIter_Check to the dynamic build because Python just moved it to function-only in 3.10 anyway. Because of that, just make sure we always grab the function in dynamic builds in earlier versions since that's what Python eventually did anyway. 3) Move Py_LIMITED_API define to configure script Can now use --with-python-stable-abi flag to customize what stable ABI version to target. Can also use an env var to do so as well. 4) Show +python/dyn-stable in :version, and allow has() feature query Not sure if the "/dyn-stable" suffix would break things, or whether we should do it another way. Or just don't show it in version and rely on has() feature checking. 5) Documentation first draft. Still need to implement v:python3_version 6) Fix PyIter_Check build breaks when compiling against Python 3.8 7) Add CI coverage stable ABI on Linux/Windows / make configurable on Windows This adds configurable options for Windows make files (both MinGW and MSVC). CI will also now exercise both traditional full API and stable ABI for Linux and Windows in the matrix for coverage. Also added a "dynamic" option to Linux matrix as a drive-by change to make other scripting languages like Ruby / Perl testable under both static and dynamic builds. 8) Fix inaccuracy in Windows docs Python's own docs are confusing but you don't actually want to use `python3.dll` for the dynamic linkage. 9) Add generated autoconf file 10) Add v:python3_version support This variable indicates the version of Python3 that Vim was built against (PY_VERSION_HEX), and will be useful to check whether the Python library you are loading in dynamically actually fits it. When built with stable ABI, it will be the limited ABI version instead (`Py_LIMITED_API`), which indicates the minimum version of Python 3 the user should have, rather than the exact match. When stable ABI is used, we won't be exposing PY_VERSION_HEX in this var because it just doesn't seem necessary to do so (the whole point of stable ABI is the promise that it will work across versions), and I don't want to confuse the user with too many variables. Also, cleaned up some documentation, and added help tags. 11) Fix Python 3.7 compat issues Fix a couple issues when using limited API < 3.8 - Crash on exit: In Python 3.7, if a heap-allocated type is destroyed before all instances are, it would cause a crash later. This happens when we destroyed `OptionsType` before calling `Py_Finalize` when using the limited API. To make it worse, later versions changed the semantics and now each instance has a strong reference to its own type and the recommendation has changed to have each instance de-ref its own type and have its type in GC traversal. To avoid dealing with these cross-version variations, we just don't free the heap type. They are static types in non-limited-API anyway and are designed to last through the entirety of the app, and we also don't restart the Python runtime and therefore do not need it to have absolutely 0 leaks. See: - https://docs.python.org/3/whatsnew/3.8.html#changes-in-the-c-api - https://docs.python.org/3/whatsnew/3.9.html#changes-in-the-c-api - PyIter_Check: This function is not provided in limited APIs older than 3.8. Previously I was trying to mock it out using manual PyType_GetSlot() but it was brittle and also does not actually work properly for static types (it will generate a Python error). Just return false. It does mean using limited API < 3.8 is not recommended as you lose the functionality to handle iterators, but from playing with plugins I couldn't find it to be an issue. - Fix loading of PyIter_Check so it will be done when limited API < 3.8. Otherwise loading a 3.7 Python lib will fail even if limited API was specified to use it. 12) Make sure to only load `PyUnicode_AsUTF8AndSize` in needed in limited API We don't use this function unless limited API >= 3.10, but we were loading it regardless. Usually it's ok in Unix-like systems where Python just has a single lib that we load from, but in Windows where there is a separate python3.dll this would not work as the symbol would not have been exposed in this more limited DLL file. This makes it much clearer under what condition is this function needed. closes: #12032 Signed-off-by: Christian Brabandt <cb@256bit.org> Co-authored-by: Yee Cheng Chin <ychin.git@gmail.com>

*usr_01.txt*	For Vim version 9.0.  Last change: 2023 May 12

		     VIM USER MANUAL - by Bram Moolenaar

			      About the manuals


This chapter introduces the manuals available with Vim.  Read this to know the
conditions under which the commands are explained.

|01.1|	Two manuals
|01.2|	Vim installed
|01.3|	Using the Vim tutor
|01.4|	Copyright

     Next chapter: |usr_02.txt|  The first steps in Vim
Table of contents: |usr_toc.txt|

==============================================================================
*01.1*	Two manuals

The Vim documentation consists of two parts:

1. The User manual
   Task oriented explanations, from simple to complex.  Reads from start to
   end like a book.

2. The Reference manual
   Precise description of how everything in Vim works.

The notation used in these manuals is explained here: |notation|


JUMPING AROUND

The text contains hyperlinks between the two parts, allowing you to quickly
jump between the description of an editing task and a precise explanation of
the commands and options used for it.  Use these two commands:

	Press  CTRL-]  to jump to a subject under the cursor.
	Press  CTRL-O  to jump back (repeat to go further back).

Many links are in vertical bars, like this: |bars|.  The bars themselves may
be hidden or invisible; see below.  An option name, like 'number', a command
in double quotes like ":write" and any other word can also be used as a link.
Try it out: Move the cursor to  CTRL-]  and press CTRL-] on it.

Other subjects can be found with the ":help" command; see |help.txt|.

The bars and stars are usually hidden with the |conceal| feature.  They also
use |hl-Ignore|, using the same color for the text as the background.  You can
make them visible with: >
	:set conceallevel=0
	:hi link HelpBar Normal
	:hi link HelpStar Normal

==============================================================================
*01.2*	Vim installed

Most of the manuals assume that Vim has been properly installed.  If you
didn't do that yet, or if Vim doesn't run properly (e.g., files can't be found
or in the GUI the menus do not show up) first read the chapter on
installation: |usr_90.txt|.
							*not-compatible*
The manuals often assume you are using Vim with Vi-compatibility switched
off.  For most commands this doesn't matter, but sometimes it is important,
e.g., for multi-level undo.  An easy way to make sure you are using a nice
setup is to copy the example vimrc file.  By doing this inside Vim you don't
have to check out where it is located.  How to do this depends on the system
you are using:

Unix: >
	:!cp -i $VIMRUNTIME/vimrc_example.vim ~/.vimrc
MS-Windows: >
	:!copy $VIMRUNTIME/vimrc_example.vim $VIM/_vimrc
Amiga: >
	:!copy $VIMRUNTIME/vimrc_example.vim $VIM/.vimrc

If the file already exists you probably want to keep it.

If you start Vim now, the 'compatible' option should be off.  You can check it
with this command: >

	:set compatible?

If it responds with "nocompatible" you are doing well.  If the response is
"compatible" you are in trouble.  You will have to find out why the option is
still set.  Perhaps the file you wrote above is not found.  Use this command
to find out: >

	:scriptnames

If your file is not in the list, check its location and name.  If it is in the
list, there must be some other place where the 'compatible' option is switched
back on.

For more info see |vimrc| and |compatible-default|.

	Note:
	This manual is about using Vim in the normal way.  There is an
	alternative called "evim" (easy Vim).  This is still Vim, but used in
	a way that resembles a click-and-type editor like Notepad.  It always
	stays in Insert mode, thus it feels very different.  It is not
	explained in the user manual, since it should be mostly
	self-explanatory.  See |evim-keys| for details.

==============================================================================
*01.3*	Using the Vim tutor				*tutor* *vimtutor*

Instead of reading the text (boring!) you can use the vimtutor to learn your
first Vim commands.  This is a 30-minute tutorial that teaches the most basic
Vim functionality hands-on.

On Unix, if Vim has been properly installed, you can start it from the shell:
>
	vimtutor

On MS-Windows you can find it in the Program/Vim menu.  Or execute
vimtutor.bat in the $VIMRUNTIME directory.

This will make a copy of the tutor file, so that you can edit it without
the risk of damaging the original.
   There are a few translated versions of the tutor.  To find out if yours is
available, use the two-letter language code.  For French: >

	vimtutor fr

On Unix, if you prefer using the GUI version of Vim, use "gvimtutor" or
"vimtutor -g" instead of "vimtutor".

For OpenVMS, if Vim has been properly installed, you can start vimtutor from a
VMS prompt with: >

	@VIM:vimtutor

Optionally add the two-letter language code as above.


On other systems, you have to do a little work:

1. Copy the tutor file.  You can do this with Vim (it knows where to find it):
>
	vim --clean -c 'e $VIMRUNTIME/tutor/tutor' -c 'w! TUTORCOPY' -c 'q'
<
   This will write the file "TUTORCOPY" in the current directory.  To use a
translated version of the tutor, append the two-letter language code to the
filename.  For French:
>
	vim --clean -c 'e $VIMRUNTIME/tutor/tutor.fr' -c 'w! TUTORCOPY' -c 'q'
<
2. Edit the copied file with Vim:
>
	vim --clean TUTORCOPY
<
   The --clean argument makes sure Vim is started with nice defaults.

3. Delete the copied file when you are finished with it:
>
	del TUTORCOPY
<
==============================================================================
*01.4*	Copyright					*manual-copyright*

The Vim user manual and reference manual are Copyright (c) 1988 by Bram
Moolenaar.  This material may be distributed only subject to the terms and
conditions set forth in the Open Publication License, v1.0 or later.  The
latest version is presently available at:
	     http://www.opencontent.org/openpub/

People who contribute to the manuals must agree with the above copyright
notice.
							*frombook*
Parts of the user manual come from the book "Vi IMproved - Vim" by Steve
Oualline (published by New Riders Publishing, ISBN: 0735710015).  The Open
Publication License applies to this book.  Only selected parts are included
and these have been modified (e.g., by removing the pictures, updating the
text for Vim 6.0 and later, fixing mistakes).  The omission of the |frombook|
tag does not mean that the text does not come from the book.

Many thanks to Steve Oualline and New Riders for creating this book and
publishing it under the OPL!  It has been a great help while writing the user
manual.  Not only by providing literal text, but also by setting the tone and
style.

If you make money through selling the manuals, you are strongly encouraged to
donate part of the profit to help AIDS victims in Uganda.  See |iccf|.

==============================================================================

Next chapter: |usr_02.txt|  The first steps in Vim

Copyright: see |manual-copyright|  vim:tw=78:ts=8:noet:ft=help:norl: