Merge pull request #25934 from bfredl/screenlinechar

refactor(grid): make screen rendering more multibyte than ever before

4 files changed, 20 insertions, 5 deletions

diff --git a/runtime/doc/mbyte.txt b/runtime/doc/mbyte.txt
index aedef87a09..0a7e0baad3 100644
--- a/runtime/doc/mbyte.txt
+++ b/runtime/doc/mbyte.txt
@@ -646,7 +646,8 @@ widespread as file format.
 A composing or combining character is used to change the meaning of the
 character before it.  The combining characters are drawn on top of the
 preceding character.
-Up to six combining characters can be displayed.
+Too big combined characters cannot be displayed, but they can still be
+inspected using the |g8| and |ga| commands described below.
 When editing text a composing character is mostly considered part of the
 preceding character.  For example "x" will delete a character and its
 following composing characters by default.
diff --git a/runtime/doc/news.txt b/runtime/doc/news.txt
index 2f48ebfeff..cb3220a630 100644
--- a/runtime/doc/news.txt
+++ b/runtime/doc/news.txt
@@ -294,6 +294,13 @@ The following changes to existing APIs or features add new behavior.
   Note that syntax highlighting of code examples requires a matching parser
   and may be affected by custom queries.
 
+• Support for rendering multibyte characters using composing characters has been
+  enhanced. The maximum limit have been increased from 1+6 codepoints to
+  31 bytes, which is guaranteed to fit all chars from before but often more.
+
+  NOTE: the regexp engine still has a hard-coded limit of considering
+  6 composing chars only.
+
 ==============================================================================
 REMOVED FEATURES                                                 *news-removed*
 
diff --git a/runtime/doc/vim_diff.txt b/runtime/doc/vim_diff.txt
index 05d7e5feb9..5e09cc2481 100644
--- a/runtime/doc/vim_diff.txt
+++ b/runtime/doc/vim_diff.txt
@@ -722,9 +722,16 @@ Options:
 <
   *'macatsui'*
   *'maxcombine'* *'mco'*
-    Nvim always displays up to 6 combining characters.  You can still edit
-    text with more than 6 combining characters, you just can't see them.
-    Use |g8| or |ga|.  See |mbyte-combining|.
+    Nvim counts maximum character sizes in bytes, not codepoints. This is
+    guaranteed to be big enough to always fit all chars properly displayed
+    in vim with 'maxcombine' set to 6.
+
+    You can still edit text with larger characters than fits in the screen buffer,
+    you just can't see them. Use |g8| or |ga|. See |mbyte-combining|.
+
+    NOTE: the rexexp engine still has a hard-coded limit of considering
+    6 composing chars only.
+
   *'maxmem'* Nvim delegates memory-management to the OS.
   *'maxmemtot'* Nvim delegates memory-management to the OS.
   printoptions
diff --git a/runtime/lua/vim/_meta/options.lua b/runtime/lua/vim/_meta/options.lua
index 19ae786177..be4a4dd49c 100644
--- a/runtime/lua/vim/_meta/options.lua
+++ b/runtime/lua/vim/_meta/options.lua
@@ -2576,7 +2576,7 @@ vim.go.fp = vim.go.formatprg
 --- security reasons.
 ---
 --- @type boolean
-vim.o.fsync = false
+vim.o.fsync = true
 vim.o.fs = vim.o.fsync
 vim.go.fsync = vim.o.fsync
 vim.go.fs = vim.go.fsync