[vim/vim] Fix: Prevent flicker when LSP server is slow (PR #18439)
17 views
Skip to first unread message
girish
Sep 29, 2025, 12:06:28 PM (yesterday) Sep 29
to vim/vim, Subscribed
Ref: girishji/vimcomplete#101 (comment)
In insert-mode completion, the leader text is temporarily deleted while searching for completion candidates.
If the LSP server responds slowly, the client may call :sleep to wait, which triggers out_flush().
This causes the deleted text to briefly disappear before being redrawn when results arrive, producing a visible flicker.
There are two possible fixes:
- Suppress flushing while a user function (e.g. LSP client) is waiting.
- Reinsert the deleted text before invoking the user function.
This PR implements (1), which is the simpler solution, though somewhat heavy-handed. If you think this may introduce unwanted side effects, I can rework it to use (2).
You can view, comment on, or merge this pull request online at:
https://github.com/vim/vim/pull/18439
Commit Summary
- f63a12d Fix: Prevent flicker when LSP server is slow
File Changes
(4 files)
- M src/globals.h (3)
- M src/insexpand.c (12)
- M src/term.c (2)
- M src/testdir/test_ins_complete.vim (4)
Patch Links:
—
Reply to this email directly, view it on GitHub.
You are receiving this because you are subscribed to this thread.
girish
Sep 29, 2025, 2:24:02 PM (yesterday) Sep 29
to vim/vim, Push
@girishji pushed 2 commits.
—
View it on GitHub or unsubscribe.
You are receiving this because you are subscribed to this thread.
Christian Brabandt
Sep 29, 2025, 4:48:41 PM (yesterday) Sep 29
to vim/vim, Subscribed
chrisbra left a comment (vim/vim#18439)thanks
—
Reply to this email directly, view it on GitHub.
You are receiving this because you are subscribed to this thread.
Christian Brabandt
Sep 29, 2025, 5:00:27 PM (yesterday) Sep 29
to vim/vim, Subscribed
—
Reply to this email directly, view it on GitHub.
You are receiving this because you are subscribed to this thread.
Maxim Kim
Sep 29, 2025, 7:27:48 PM (yesterday) Sep 29
to vim/vim, Subscribed
habamax left a comment (vim/vim#18439)Thx. It is better and worse at the same time :).
- So flicker has gone -- which is great.
- It responds to keypresses way slower -- which is not that great (not sure if this even could be fixed)
- At some point backspace becomes
^?https://asciinema.org/a/BhKKa4MYC1oTWwJbWIKlzW9yn
—
Reply to this email directly, view it on GitHub.
You are receiving this because you are subscribed to this thread.
Maxim Kim
Sep 29, 2025, 7:38:41 PM (24 hours ago) Sep 29
to vim/vim, Subscribed
habamax left a comment (vim/vim#18439)Screencast doesn't show, but there are noticeable delays between keypress and char insertion, which feels not great.
—
Reply to this email directly, view it on GitHub.
You are receiving this because you are subscribed to this thread.
girish
Sep 29, 2025, 9:34:40 PM (22 hours ago) Sep 29
to vim/vim, Subscribed
girishji left a comment (vim/vim#18439)I'll look into this.
—
Reply to this email directly, view it on GitHub.
You are receiving this because you are subscribed to this thread.
Christian Brabandt
3:59 PM (4 hours ago) 3:59 PM
to vim/vim, Subscribed
chrisbra left a comment (vim/vim#18439)That patch is wrong. It causes overflow of out_pos, because when no_flush is set, out_char_nf() happily writes out-of-bound because the out_pos counter is no longer reset when out_flush() is called. I'll revert this for now.
It causes segfault on MS-Windows: #18450
Stack trace:
==377936==T0: stack [0x000000e40000,0x000000f40000) size 0x100000; local=0x000000f3eec0
==377936==AddressSanitizer Init done
=================================================================
==377936==ERROR: AddressSanitizer: global-buffer-overflow on address 0x7ff61ef5c0c0 at pc 0x7ff61eb98668 bp 0x000000f35560 sp 0x000000f35568
WRITE of size 1 at 0x7ff61ef5c0c0 thread T0
#0 0x7ff61eb98667 in out_str_nf c:\Users\Christian Brabandt\code\vim\src\term.c:2893
#1 0x7ff61eb9dd06 in out_str c:\Users\Christian Brabandt\code\vim\src\term.c:2987
#2 0x7ff61eb134fc in windgoto c:\Users\Christian Brabandt\code\vim\src\screen.c:3213
#3 0x7ff61eb18907 in screen_char c:\Users\Christian Brabandt\code\vim\src\screen.c:1978
#4 0x7ff61eb1513d in screen_puts_len c:\Users\Christian Brabandt\code\vim\src\screen.c:1501
#5 0x7ff61ea0be19 in screen_puts_mbyte c:\Users\Christian Brabandt\code\vim\src\message.c:2238
#6 0x7ff61ea0b2fb in msg_puts_display c:\Users\Christian Brabandt\code\vim\src\message.c:2553
#7 0x7ff61ea0bcd8 in msg_puts_attr_len c:\Users\Christian Brabandt\code\vim\src\message.c:2362
#8 0x7ff61ea0feb1 in msg_outtrans_len_attr c:\Users\Christian Brabandt\code\vim\src\message.c:1816
#9 0x7ff61ea0dd4a in msg_outtrans_attr c:\Users\Christian Brabandt\code\vim\src\message.c:1696
#10 0x7ff61ea0dd4a in msg_attr_keep c:\Users\Christian Brabandt\code\vim\src\message.c:192
#11 0x7ff61ea10448 in msg_attr c:\Users\Christian Brabandt\code\vim\src\message.c:139
#12 0x7ff61ea10448 in msg_source c:\Users\Christian Brabandt\code\vim\src\message.c:553
#13 0x7ff61ea0d45e in emsg_core c:\Users\Christian Brabandt\code\vim\src\message.c:782
#14 0x7ff61ebca4e6 in undo_allowed c:\Users\Christian Brabandt\code\vim\src\undo.c:338
#15 0x7ff61e9b4a83 in f_complete c:\Users\Christian Brabandt\code\vim\src\insexpand.c:3877
#16 0x7ff61e8ec29c in call_internal_func c:\Users\Christian Brabandt\code\vim\src\evalfunc.c:3497
#17 0x7ff61ebe8cdb in call_func c:\Users\Christian Brabandt\code\vim\src\userfunc.c:4176
#18 0x7ff61ebe9d75 in get_func_tv c:\Users\Christian Brabandt\code\vim\src\userfunc.c:2190
#19 0x7ff61ebd4c73 in ex_call_inner c:\Users\Christian Brabandt\code\vim\src\userfunc.c:6510
#20 0x7ff61ebe5264 in ex_call c:\Users\Christian Brabandt\code\vim\src\userfunc.c:6868
#21 0x7ff61e92a52c in do_one_cmd c:\Users\Christian Brabandt\code\vim\src\ex_docmd.c:2629
#22 0x7ff61e931b04 in do_cmdline c:\Users\Christian Brabandt\code\vim\src\ex_docmd.c:1041
#23 0x7ff61ebdb3d5 in call_user_func c:\Users\Christian Brabandt\code\vim\src\userfunc.c:3312
#24 0x7ff61ebda2b1 in call_user_func_check c:\Users\Christian Brabandt\code\vim\src\userfunc.c:3485
#25 0x7ff61ebe909c in call_func c:\Users\Christian Brabandt\code\vim\src\userfunc.c:4158
#26 0x7ff61ebe9d75 in get_func_tv c:\Users\Christian Brabandt\code\vim\src\userfunc.c:2190
#27 0x7ff61ebd4c73 in ex_call_inner c:\Users\Christian Brabandt\code\vim\src\userfunc.c:6510
#28 0x7ff61ebe5264 in ex_call c:\Users\Christian Brabandt\code\vim\src\userfunc.c:6868
#29 0x7ff61e92a52c in do_one_cmd c:\Users\Christian Brabandt\code\vim\src\ex_docmd.c:2629
#30 0x7ff61e931b04 in do_cmdline c:\Users\Christian Brabandt\code\vim\src\ex_docmd.c:1041
#31 0x7ff61ebdb3d5 in call_user_func c:\Users\Christian Brabandt\code\vim\src\userfunc.c:3312
#32 0x7ff61ebda2b1 in call_user_func_check c:\Users\Christian Brabandt\code\vim\src\userfunc.c:3485
#33 0x7ff61ebe909c in call_func c:\Users\Christian Brabandt\code\vim\src\userfunc.c:4158
#34 0x7ff61ebeb943 in call_callback c:\Users\Christian Brabandt\code\vim\src\userfunc.c:3818
#35 0x7ff61e9ac80a in expand_by_function c:\Users\Christian Brabandt\code\vim\src\insexpand.c:3612
#36 0x7ff61e9a7b68 in get_next_completion_match c:\Users\Christian Brabandt\code\vim\src\insexpand.c:5357
#37 0x7ff61e9a6d6e in ins_compl_get_exp c:\Users\Christian Brabandt\code\vim\src\insexpand.c:5599
#38 0x7ff61e9a59b2 in find_next_completion_match c:\Users\Christian Brabandt\code\vim\src\insexpand.c:6151
#39 0x7ff61e9a55a9 in ins_compl_next c:\Users\Christian Brabandt\code\vim\src\insexpand.c:6265
#40 0x7ff61e9b6eee in ins_complete c:\Users\Christian Brabandt\code\vim\src\insexpand.c:7320
#41 0x7ff61e8b6ff4 in edit c:\Users\Christian Brabandt\code\vim\src\edit.c:1329
#42 0x7ff61ea3139a in invoke_edit c:\Users\Christian Brabandt\code\vim\src\normal.c:7139
#43 0x7ff61ea318e9 in nv_edit c:\Users\Christian Brabandt\code\vim\src\normal.c:7110
#44 0x7ff61ea43efc in normal_cmd c:\Users\Christian Brabandt\code\vim\src\normal.c:952
#45 0x7ff61e92d809 in exec_normal c:\Users\Christian Brabandt\code\vim\src\ex_docmd.c:9436
#46 0x7ff61e8e70b3 in f_feedkeys c:\Users\Christian Brabandt\code\vim\src\evalfunc.c:5151
#47 0x7ff61e8ec29c in call_internal_func c:\Users\Christian Brabandt\code\vim\src\evalfunc.c:3497
#48 0x7ff61ebe8cdb in call_func c:\Users\Christian Brabandt\code\vim\src\userfunc.c:4176
#49 0x7ff61ebe9d75 in get_func_tv c:\Users\Christian Brabandt\code\vim\src\userfunc.c:2190
#50 0x7ff61ebd4c73 in ex_call_inner c:\Users\Christian Brabandt\code\vim\src\userfunc.c:6510
#51 0x7ff61ebe5264 in ex_call c:\Users\Christian Brabandt\code\vim\src\userfunc.c:6868
#52 0x7ff61e92a52c in do_one_cmd c:\Users\Christian Brabandt\code\vim\src\ex_docmd.c:2629
#53 0x7ff61e931b04 in do_cmdline c:\Users\Christian Brabandt\code\vim\src\ex_docmd.c:1041
#54 0x7ff61e930e83 in do_cmdline_cmd c:\Users\Christian Brabandt\code\vim\src\ex_docmd.c:635
#55 0x7ff61eba1977 in f_assert_fails c:\Users\Christian Brabandt\code\vim\src\testing.c:624
#56 0x7ff61e8ec29c in call_internal_func c:\Users\Christian Brabandt\code\vim\src\evalfunc.c:3497
#57 0x7ff61ebe8cdb in call_func c:\Users\Christian Brabandt\code\vim\src\userfunc.c:4176
#58 0x7ff61ebe9d75 in get_func_tv c:\Users\Christian Brabandt\code\vim\src\userfunc.c:2190
#59 0x7ff61ebd4c73 in ex_call_inner c:\Users\Christian Brabandt\code\vim\src\userfunc.c:6510
#60 0x7ff61ebe5264 in ex_call c:\Users\Christian Brabandt\code\vim\src\userfunc.c:6868
#61 0x7ff61e92a52c in do_one_cmd c:\Users\Christian Brabandt\code\vim\src\ex_docmd.c:2629
#62 0x7ff61e931b04 in do_cmdline c:\Users\Christian Brabandt\code\vim\src\ex_docmd.c:1041
#63 0x7ff61ebdb3d5 in call_user_func c:\Users\Christian Brabandt\code\vim\src\userfunc.c:3312
#64 0x7ff61ebda2b1 in call_user_func_check c:\Users\Christian Brabandt\code\vim\src\userfunc.c:3485
#65 0x7ff61ebe909c in call_func c:\Users\Christian Brabandt\code\vim\src\userfunc.c:4158
#66 0x7ff61ebe9d75 in get_func_tv c:\Users\Christian Brabandt\code\vim\src\userfunc.c:2190
#67 0x7ff61ebd4c73 in ex_call_inner c:\Users\Christian Brabandt\code\vim\src\userfunc.c:6510
#68 0x7ff61ebe5264 in ex_call c:\Users\Christian Brabandt\code\vim\src\userfunc.c:6868
#69 0x7ff61e92a52c in do_one_cmd c:\Users\Christian Brabandt\code\vim\src\ex_docmd.c:2629
#70 0x7ff61e931b04 in do_cmdline c:\Users\Christian Brabandt\code\vim\src\ex_docmd.c:1041
#71 0x7ff61ea3ddb3 in nv_colon c:\Users\Christian Brabandt\code\vim\src\normal.c:3170
#72 0x7ff61ea43efc in normal_cmd c:\Users\Christian Brabandt\code\vim\src\normal.c:952
#73 0x7ff61e9d07e9 in main_loop c:\Users\Christian Brabandt\code\vim\src\main.c:1635
#74 0x7ff61e9cf31e in vim_main2 c:\Users\Christian Brabandt\code\vim\src\main.c:973
#75 0x7ff61e9cfd8b in VimMain c:\Users\Christian Brabandt\code\vim\src\main.c:446
#76 0x7ff61ec7322f in wWinMain c:\Users\Christian Brabandt\code\vim\src\os_w32exe.c:39
#77 0x7ff61e7e35b1 in invoke_main D:\a\_work\1\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:118
#78 0x7ff61e7e35b1 in __scrt_common_main_seh D:\a\_work\1\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:288
#79 0x7ffc5f3de8d6 (C:\Windows\System32\KERNEL32.DLL+0x18002e8d6)
#80 0x7ffc60d68d9b (C:\Windows\SYSTEM32\ntdll.dll+0x180008d9b)
0x7ff61ef5c0c0 is located 0 bytes after global variable 'out_buf' defined in 'term.c:2759:15' (0x7ff61ef5b8c0) of size 2048
SUMMARY: AddressSanitizer: global-buffer-overflow c:\Users\Christian Brabandt\code\vim\src\term.c:2893 in out_str_nf
Shadow bytes around the buggy address:
0x7ff61ef5be00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x7ff61ef5be80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x7ff61ef5bf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x7ff61ef5bf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x7ff61ef5c000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x7ff61ef5c080: 00 00 00 00 00 00 00 00[f9]f9 f9 f9 f9 f9 f9 f9
0x7ff61ef5c100: f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9
0x7ff61ef5c180: f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9
0x7ff61ef5c200: f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9
0x7ff61ef5c280: f9 f9 f9 f9 f9 f9 f9 f9 04 f9 f9 f9 04 f9 f9 f9
0x7ff61ef5c300: 00 f9 f9 f9 04 f9 f9 f9 00 00 00 00 00 00 00 00
Shadow byte legend (one shadow byte represents 8 application bytes):
Addressable: 00
Partially addressable: 01 02 03 04 05 06 07
Heap left redzone: fa
Freed heap region: fd
Stack left redzone: f1
Stack mid redzone: f2
Stack right redzone: f3
Stack after return: f5
Stack use after scope: f8
Global redzone: f9
Global init order: f6
Poisoned by user: f7
Container overflow: fc
Array cookie: ac
Intra object redzone: bb
ASan internal: fe
Left alloca redzone: ca
Right alloca redzone: cb
==377936==ABORTING
—
Reply to this email directly, view it on GitHub.
You are receiving this because you are subscribed to this thread.
Reply all
Reply to author
Forward
0 new messages