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>

/* gui_photon.c */
void gui_ph_encoding_changed(int new_encoding);
void gui_mch_prepare(int *argc, char **argv);
int gui_mch_init(void);
int gui_mch_init_check(void);
int gui_mch_open(void);
void gui_mch_exit(int rc);
void gui_mch_update(void);
int gui_mch_wait_for_chars(int wtime);
char_u *gui_mch_browse(int saving, char_u *title, char_u *default_name, char_u *ext, char_u *initdir, char_u *filter);
int gui_mch_dialog(int type, char_u *title, char_u *message, char_u *buttons, int default_button, char_u *textfield, int ex_cmd);
int gui_mch_get_winpos(int *x, int *y);
void gui_mch_set_winpos(int x, int y);
void gui_mch_set_shellsize(int width, int height, int min_width, int min_height, int base_width, int base_height, int direction);
void gui_mch_get_screen_dimensions(int *screen_w, int *screen_h);
void gui_mch_iconify(void);
void gui_mch_set_foreground(void);
void gui_mch_settitle(char_u *title, char_u *icon);
void gui_mch_set_scrollbar_thumb(scrollbar_T *sb, int val, int size, int max);
void gui_mch_set_scrollbar_pos(scrollbar_T *sb, int x, int y, int w, int h);
int gui_mch_get_scrollbar_xpadding(void);
int gui_mch_get_scrollbar_ypadding(void);
void gui_mch_create_scrollbar(scrollbar_T *sb, int orient);
void gui_mch_enable_scrollbar(scrollbar_T *sb, int flag);
void gui_mch_destroy_scrollbar(scrollbar_T *sb);
void mch_set_mouse_shape(int shape);
void gui_mch_mousehide(int hide);
void gui_mch_getmouse(int *x, int *y);
void gui_mch_setmouse(int x, int y);
guicolor_T gui_mch_get_rgb(guicolor_T pixel);
void gui_mch_new_colors(void);
guicolor_T gui_mch_get_color(char_u *name);
guicolor_T gui_mch_get_rgb_color(int r, int g, int b);
void gui_mch_set_fg_color(guicolor_T color);
void gui_mch_set_bg_color(guicolor_T color);
void gui_mch_set_sp_color(guicolor_T color);
void gui_mch_invert_rectangle(int row, int col, int nr, int nc);
void gui_mch_clear_block(int row1, int col1, int row2, int col2);
void gui_mch_clear_all(void);
void gui_mch_delete_lines(int row, int num_lines);
void gui_mch_insert_lines(int row, int num_lines);
void gui_mch_draw_string(int row, int col, char_u *s, int len, int flags);
void gui_mch_draw_hollow_cursor(guicolor_T color);
void gui_mch_draw_part_cursor(int w, int h, guicolor_T color);
int gui_mch_is_blinking(void);
int gui_mch_is_blink_off(void);
void gui_mch_set_blinking(long wait, long on, long off);
void gui_mch_start_blink(void);
void gui_mch_stop_blink(int may_call_gui_update_cursor);
void gui_mch_beep(void);
void gui_mch_flash(int msec);
void gui_mch_flush(void);
void gui_mch_set_text_area_pos(int x, int y, int w, int h);
int gui_mch_haskey(char_u *name);
void gui_mch_enable_menu(int flag);
void gui_mch_set_menu_pos(int x, int y, int w, int h);
void gui_mch_add_menu(vimmenu_T *menu, int index);
void gui_mch_add_menu_item(vimmenu_T *menu, int index);
void gui_mch_destroy_menu(vimmenu_T *menu);
void gui_mch_menu_grey(vimmenu_T *menu, int grey);
void gui_mch_menu_hidden(vimmenu_T *menu, int hidden);
void gui_mch_draw_menubar(void);
void gui_mch_show_popupmenu(vimmenu_T *menu);
void gui_mch_toggle_tearoffs(int enable);
void gui_mch_show_toolbar(int showit);
int gui_mch_init_font(char_u *vim_font_name, int fontset);
int gui_mch_adjust_charheight(void);
GuiFont gui_mch_get_font(char_u *vim_font_name, int report_error);
char_u *gui_mch_get_fontname(GuiFont font, char_u *name);
void gui_mch_set_font(GuiFont font);
void gui_mch_free_font(GuiFont font);
/* vim: set ft=c : */