feat(mbyte): support extended grapheme clusters including more emoji

Use the grapheme break algorithm from utf8proc to support grapheme
clusters from recent unicode versions.

Handle variant selector VS16 turning some codepoints into double-width
emoji. This means we need to use ptr2cells rather than char2cells when
possible.

7 files changed, 287 insertions, 38 deletions

diff --git a/test/functional/api/vim_spec.lua b/test/functional/api/vim_spec.lua
index 4210b7ecf0..074d3ac0a3 100644
--- a/test/functional/api/vim_spec.lua
+++ b/test/functional/api/vim_spec.lua
@@ -1435,6 +1435,28 @@ describe('API', function()
     it('cannot handle NULs', function()
       eq(0, api.nvim_strwidth('\0abc'))
     end)
+
+    it('can handle emoji with variant selectors and ZWJ', function()
+      local selector = '❤️'
+      eq(2, fn.strchars(selector))
+      eq(1, fn.strcharlen(selector))
+      eq(2, api.nvim_strwidth(selector))
+
+      local no_selector = '❤'
+      eq(1, fn.strchars(no_selector))
+      eq(1, fn.strcharlen(no_selector))
+      eq(1, api.nvim_strwidth(no_selector))
+
+      local selector_zwj_selector = '🏳️‍⚧️'
+      eq(5, fn.strchars(selector_zwj_selector))
+      eq(1, fn.strcharlen(selector_zwj_selector))
+      eq(2, api.nvim_strwidth(selector_zwj_selector))
+
+      local emoji_zwj_emoji = '🧑‍🌾'
+      eq(3, fn.strchars(emoji_zwj_emoji))
+      eq(1, fn.strcharlen(emoji_zwj_emoji))
+      eq(2, api.nvim_strwidth(emoji_zwj_emoji))
+    end)
   end)
 
   describe('nvim_get_current_line, nvim_set_current_line', function()
diff --git a/test/functional/ui/decorations_spec.lua b/test/functional/ui/decorations_spec.lua
index 1709819575..61a5e1d6f7 100644
--- a/test/functional/ui/decorations_spec.lua
+++ b/test/functional/ui/decorations_spec.lua
@@ -5620,6 +5620,27 @@ l5
       ]]
     })
   end)
+
+  it('supports emoji as signs', function()
+    insert(example_test3)
+    feed 'gg'
+    api.nvim_buf_set_extmark(0, ns, 1, 0, {sign_text='🧑‍🌾'})
+    -- VS16 can change width of character
+    api.nvim_buf_set_extmark(0, ns, 2, 0, {sign_text='❤️'})
+    api.nvim_buf_set_extmark(0, ns, 3, 0, {sign_text='❤'})
+    api.nvim_buf_set_extmark(0, ns, 4, 0, {sign_text='❤x'})
+    screen:expect([[
+      {7:  }^l1                                              |
+      🧑‍🌾l2                                              |
+      ❤️l3                                              |
+      ❤ l4                                              |
+      ❤xl5                                              |
+      {7:  }                                                |
+      {1:~                                                 }|*3
+                                                        |
+    ]])
+    eq("Invalid 'sign_text'", pcall_err(api.nvim_buf_set_extmark, 0, ns, 5, 0, {sign_text='❤️x'}))
+  end)
 end)
 
 describe('decorations: virt_text', function()
diff --git a/test/functional/ui/messages_spec.lua b/test/functional/ui/messages_spec.lua
index 07192800e5..036b5ceefc 100644
--- a/test/functional/ui/messages_spec.lua
+++ b/test/functional/ui/messages_spec.lua
@@ -1436,6 +1436,41 @@ vimComment     xxx match /\s"[^\-:.%#=*].*$/ms=s+1,lc=1  excludenl contains=@vim
     }
   end)
 
+  it('supports nvim_echo messages with emoji', function()
+    -- stylua: ignore
+    async_meths.nvim_echo(
+      { { 'wow, 🏳️‍⚧️🧑‍🌾❤️😂🏴‍☠️\nvariant ❤️ one\nvariant ❤ two' } }, true, {}
+    )
+
+    screen:expect([[
+                                                                  |
+      {1:~                                                           }|
+      {3:                                                            }|
+      wow, 🏳️‍⚧️🧑‍🌾❤️😂🏴‍☠️                                             |
+      variant ❤️ one                                              |
+      variant ❤ two                                               |
+      {6:Press ENTER or type command to continue}^                     |
+    ]])
+
+    feed '<cr>'
+    screen:expect([[
+      ^                                                            |
+      {1:~                                                           }|*5
+                                                                  |
+    ]])
+
+    feed ':messages<cr>'
+    screen:expect([[
+                                                                  |
+      {1:~                                                           }|
+      {3:                                                            }|
+      wow, 🏳️‍⚧️🧑‍🌾❤️😂🏴‍☠️                                             |
+      variant ❤️ one                                              |
+      variant ❤ two                                               |
+      {6:Press ENTER or type command to continue}^                     |
+    ]])
+  end)
+
   it('prints lines in Ex mode correctly with a burst of carriage returns #19341', function()
     command('set number')
     api.nvim_buf_set_lines(0, 0, 0, true, { 'aaa', 'bbb', 'ccc' })
diff --git a/test/functional/ui/multibyte_spec.lua b/test/functional/ui/multibyte_spec.lua
index dc25a09d0d..f16f750ea1 100644
--- a/test/functional/ui/multibyte_spec.lua
+++ b/test/functional/ui/multibyte_spec.lua
@@ -296,6 +296,86 @@ describe('multibyte rendering', function()
     ]],
     }
   end)
+
+  it('supports emoji with variant selectors and ZWJ', function()
+    command('set ruler')
+    insert('🏳️‍⚧️')
+    screen:expect([[
+      ^🏳️‍⚧️                                                          |
+      {1:~                                                           }|*4
+                                                1,1           All |
+    ]])
+
+    feed('a word<esc>')
+    screen:expect([[
+      🏳️‍⚧️ wor^d                                                     |
+      {1:~                                                           }|*4
+                                                1,21-7        All |
+    ]])
+
+    feed('0')
+    screen:expect([[
+      ^🏳️‍⚧️ word                                                     |
+      {1:~                                                           }|*4
+                                                1,1           All |
+    ]])
+
+    feed('l')
+    screen:expect([[
+        🏳️‍⚧️^ word                                                     |
+        {1:~                                                           }|*4
+                                                  1,17-3        All |
+    ]])
+
+    feed('h')
+    screen:expect([[
+      ^🏳️‍⚧️ word                                                     |
+      {1:~                                                           }|*4
+                                                1,1           All |
+    ]])
+
+    feed('o❤️ variant selected<esc>')
+    screen:expect([[
+      🏳️‍⚧️ word                                                     |
+      ❤️ variant selecte^d                                         |
+      {1:~                                                           }|*3
+                                                2,23-19       All |
+    ]])
+
+    feed('0')
+    screen:expect([[
+      🏳️‍⚧️ word                                                     |
+      ^❤️ variant selected                                         |
+      {1:~                                                           }|*3
+                                                2,1           All |
+    ]])
+
+    feed('l')
+    screen:expect([[
+      🏳️‍⚧️ word                                                     |
+      ❤️^ variant selected                                         |
+      {1:~                                                           }|*3
+                                                2,7-3         All |
+    ]])
+
+    feed('h')
+    screen:expect([[
+      🏳️‍⚧️ word                                                     |
+      ^❤️ variant selected                                         |
+      {1:~                                                           }|*3
+                                                2,1           All |
+    ]])
+
+    -- without selector: single width (note column 18 and not 19)
+    feed('o❤ variant selected<esc>')
+    screen:expect([[
+      🏳️‍⚧️ word                                                     |
+      ❤️ variant selected                                         |
+      ❤ variant selecte^d                                          |
+      {1:~                                                           }|*2
+                                                3,20-18       All |
+    ]])
+  end)
 end)
 
 describe('multibyte rendering: statusline', function()
@@ -348,11 +428,12 @@ describe('multibyte rendering: statusline', function()
   it('non-printable followed by MAX_MCO unicode combination points', function()
     command('set statusline=Ÿ̸⃯ᷰ⃐⃧⃝')
     -- U+9F + U+1DF0 + U+20EF + U+0338 + U+20D0 + U+20E7 + U+20DD
+    -- TODO: not ideal, better with plain ">" and then space+combining
     screen:expect([[
-    ^                                        |
-    {1:~                                       }|
-    {3:<9f><1df0><20ef><0338><20d0><20e7><20dd>}|
-                                            |
+      ^                                        |
+      {1:~                                       }|
+      {3:<9f≯⃯ᷰ⃐⃧⃝                                    }|
+                                              |
     ]])
   end)
 
@@ -368,9 +449,20 @@ describe('multibyte rendering: statusline', function()
     }
   end)
 
-  it('unprintable chars in filename with default stl', function()
+  it('emoji with ZWJ in filename with default stl', function()
     command('file 🧑‍💻')
-    -- TODO: this is wrong but avoids a crash
+    screen:expect {
+      grid = [[
+      ^                                        |
+      {1:~                                       }|
+      {3:🧑‍💻                                      }|
+                                              |
+    ]],
+    }
+  end)
+
+  it('unprintable chars in filename with default stl', function()
+    command('file 🧑​💻')
     screen:expect {
       grid = [[
       ^                                        |
@@ -381,15 +473,27 @@ describe('multibyte rendering: statusline', function()
     }
   end)
 
-  it('unprintable chars in filename with custom stl', function()
+  it('emoji with ZWJ in filename with custom stl', function()
     command('set statusline=xx%#ErrorMsg#%f%##yy')
     command('file 🧑‍💻')
-    -- TODO: this is also wrong but also avoids a crash
     screen:expect {
       grid = [[
       ^                                        |
       {1:~                                       }|
-      {3:xx}{9:🧑<200d>💻}{3:yy                          }|
+      {3:xx}{9:🧑‍💻}{3:yy                                  }|
+                                              |
+    ]],
+    }
+  end)
+
+  it('unprintable chars in filename with custom stl', function()
+    command('set statusline=xx%#ErrorMsg#%f%##yy')
+    command('file 🧑​💻')
+    screen:expect {
+      grid = [[
+      ^                                        |
+      {1:~                                       }|
+      {3:xx}{9:🧑<200b>💻}{3:yy                          }|
                                               |
     ]],
     }
diff --git a/test/old/testdir/test_functions.vim b/test/old/testdir/test_functions.vim
index 7047a62017..ffe7f3fb39 100644
--- a/test/old/testdir/test_functions.vim
+++ b/test/old/testdir/test_functions.vim
@@ -3663,7 +3663,7 @@ func Test_string_reverse()
     call assert_equal('', reverse(v:_null_string))
     for [s1, s2] in [['', ''], ['a', 'a'], ['ab', 'ba'], ['abc', 'cba'],
                    \ ['abcd', 'dcba'], ['«-«-»-»', '»-»-«-«'],
-                   \ ['🇦', '🇦'], ['🇦🇧', '🇧🇦'], ['🇦🇧🇨', '🇨🇧🇦'],
+                   \ ['🇦', '🇦'], ['🇦🇧', '🇦🇧'], ['🇦🇧🇨', '🇨🇦🇧'],
                    \ ['🇦«🇧-🇨»🇩', '🇩»🇨-🇧«🇦']]
       call assert_equal(s2, reverse(s1))
     endfor
diff --git a/test/old/testdir/test_normal.vim b/test/old/testdir/test_normal.vim
index 8088b1fc57..3ebc9a69a4 100644
--- a/test/old/testdir/test_normal.vim
+++ b/test/old/testdir/test_normal.vim
@@ -3897,9 +3897,9 @@ func Test_normal_count_after_operator()
   bw!
 endfunc
 
-func Test_normal_gj_on_extra_wide_char()
+func Test_normal_gj_on_6_cell_wide_unprintable_char()
   new | 25vsp
-  let text='1 foooooooo ar e  ins‍zwe1 foooooooo ins‍zwei' .
+  let text='1 foooooooo ar e  ins​zwe1 foooooooo ins​zwei' .
          \ ' i drei vier fünf sechs sieben acht un zehn elf zwöfl' .
          \ ' dreizehn v ierzehn fünfzehn'
   put =text
diff --git a/test/unit/mbyte_spec.lua b/test/unit/mbyte_spec.lua
index 8fcc67d20b..787a8862ae 100644
--- a/test/unit/mbyte_spec.lua
+++ b/test/unit/mbyte_spec.lua
@@ -3,8 +3,15 @@ local itp = t.gen_itp(it)
 
 local ffi = t.ffi
 local eq = t.eq
+local to_cstr = t.to_cstr
+local ok = t.ok
 
-local lib = t.cimport('./src/nvim/mbyte.h', './src/nvim/charset.h', './src/nvim/grid.h')
+local lib = t.cimport(
+  './src/nvim/mbyte.h',
+  './src/nvim/charset.h',
+  './src/nvim/grid.h',
+  './src/nvim/option_vars.h'
+)
 
 describe('mbyte', function()
   -- Convert from bytes to string
@@ -45,12 +52,21 @@ describe('mbyte', function()
     end)
   end
 
-  describe('utfc_ptr2schar_len', function()
+  describe('utfc_ptr2schar', function()
     local function test_seq(seq)
       local firstc = ffi.new('int[1]')
       local buf = ffi.new('char[32]')
-      lib.schar_get(buf, lib.utfc_ptr2schar_len(to_string(seq), #seq, firstc))
-      return { ffi.string(buf), firstc[0] }
+      lib.schar_get(buf, lib.utfc_ptr2schar(to_string(seq), firstc))
+      local str = ffi.string(buf)
+      if 1 > 2 then -- for debugging
+        local tabel = {}
+        for i = 1, #str do
+          table.insert(tabel, string.format('0x%02x', string.byte(str, i)))
+        end
+        print('{ ' .. table.concat(tabel, ', ') .. ' }')
+        io.stdout:flush()
+      end
+      return { str, firstc[0] }
     end
 
     local function byte(val)
@@ -88,7 +104,9 @@ describe('mbyte', function()
       eq(byte(0x7f), test_seq { 0x7f, 0xc2, 0x80 })
 
       -- Combining character is U+0300
-      eq({ '\x7f\xcc\x80', 0x7f }, test_seq { 0x7f, 0xcc, 0x80 })
+      eq({ '\x29\xcc\x80', 0x29 }, test_seq { 0x29, 0xcc, 0x80 })
+      -- invalid start byte for combining
+      eq({ '\x7f', 0x7f }, test_seq { 0x7f, 0xcc, 0x80 })
 
       -- No UTF-8 sequence
       eq({ '', 0xc2 }, test_seq { 0xc2, 0x7f, 0xcc })
@@ -102,18 +120,21 @@ describe('mbyte', function()
     itp('4-byte sequences', function()
       -- No following combining character
       eq(byte(0x7f), test_seq { 0x7f, 0x7f, 0xcc, 0x80 })
+      eq(byte(0x29), test_seq { 0x29, 0x29, 0xcc, 0x80 })
       -- No second UTF-8 character
       eq(byte(0x7f), test_seq { 0x7f, 0xc2, 0xcc, 0x80 })
 
       -- Combining character U+0300
-      eq({ '\x7f\xcc\x80', 0x7f }, test_seq { 0x7f, 0xcc, 0x80, 0xcc })
+      eq({ '\x29\xcc\x80', 0x29 }, test_seq { 0x29, 0xcc, 0x80, 0xcc })
 
       -- No UTF-8 sequence
       eq({ '', 0xc2 }, test_seq { 0xc2, 0x7f, 0xcc, 0x80 })
       -- No following UTF-8 character
       eq({ '\xc2\x80', 0x80 }, test_seq { 0xc2, 0x80, 0xcc, 0xcc })
       -- Combining character U+0301
-      eq({ '\xc2\x80\xcc\x81', 0x80 }, test_seq { 0xc2, 0x80, 0xcc, 0x81 })
+      eq({ '\xc2\xbc\xcc\x81', 0xbc }, test_seq { 0xc2, 0xbc, 0xcc, 0x81 })
+      -- U+0080 : not a valid start char
+      eq({ '\xc2\x80', 0x80 }, test_seq { 0xc2, 0x80, 0xcc, 0x81 })
 
       -- One UTF-8 character
       eq({ '\xf4\x80\x80\x80', 0x100000 }, test_seq { 0xf4, 0x80, 0x80, 0x80 })
@@ -126,36 +147,36 @@ describe('mbyte', function()
       eq(byte(0x7f), test_seq { 0x7f, 0xc2, 0xcc, 0x80, 0x80 })
 
       -- Combining character U+0300
-      eq({ '\x7f\xcc\x80', 0x7f }, test_seq { 0x7f, 0xcc, 0x80, 0xcc, 0x00 })
+      eq({ '\x29\xcc\x80', 0x29 }, test_seq { 0x29, 0xcc, 0x80, 0xcc, 0x00 })
 
       -- Combining characters U+0300 and U+0301
-      eq({ '\x7f\xcc\x80\xcc\x81', 0x7f }, test_seq { 0x7f, 0xcc, 0x80, 0xcc, 0x81 })
+      eq({ '\x29\xcc\x80\xcc\x81', 0x29 }, test_seq { 0x29, 0xcc, 0x80, 0xcc, 0x81 })
       -- Combining characters U+0300, U+0301, U+0302
       eq(
-        { '\x7f\xcc\x80\xcc\x81\xcc\x82', 0x7f },
-        test_seq { 0x7f, 0xcc, 0x80, 0xcc, 0x81, 0xcc, 0x82 }
+        { '\x29\xcc\x80\xcc\x81\xcc\x82', 0x29 },
+        test_seq { 0x29, 0xcc, 0x80, 0xcc, 0x81, 0xcc, 0x82 }
       )
       -- Combining characters U+0300, U+0301, U+0302, U+0303
       eq(
-        { '\x7f\xcc\x80\xcc\x81\xcc\x82\xcc\x83', 0x7f },
-        test_seq { 0x7f, 0xcc, 0x80, 0xcc, 0x81, 0xcc, 0x82, 0xcc, 0x83 }
+        { '\x29\xcc\x80\xcc\x81\xcc\x82\xcc\x83', 0x29 },
+        test_seq { 0x29, 0xcc, 0x80, 0xcc, 0x81, 0xcc, 0x82, 0xcc, 0x83 }
       )
       -- Combining characters U+0300, U+0301, U+0302, U+0303, U+0304
       eq(
-        { '\x7f\xcc\x80\xcc\x81\xcc\x82\xcc\x83\xcc\x84', 0x7f },
-        test_seq { 0x7f, 0xcc, 0x80, 0xcc, 0x81, 0xcc, 0x82, 0xcc, 0x83, 0xcc, 0x84 }
+        { '\x29\xcc\x80\xcc\x81\xcc\x82\xcc\x83\xcc\x84', 0x29 },
+        test_seq { 0x29, 0xcc, 0x80, 0xcc, 0x81, 0xcc, 0x82, 0xcc, 0x83, 0xcc, 0x84 }
       )
       -- Combining characters U+0300, U+0301, U+0302, U+0303, U+0304, U+0305
       eq(
-        { '\x7f\xcc\x80\xcc\x81\xcc\x82\xcc\x83\xcc\x84\xcc\x85', 0x7f },
-        test_seq { 0x7f, 0xcc, 0x80, 0xcc, 0x81, 0xcc, 0x82, 0xcc, 0x83, 0xcc, 0x84, 0xcc, 0x85 }
+        { '\x29\xcc\x80\xcc\x81\xcc\x82\xcc\x83\xcc\x84\xcc\x85', 0x29 },
+        test_seq { 0x29, 0xcc, 0x80, 0xcc, 0x81, 0xcc, 0x82, 0xcc, 0x83, 0xcc, 0x84, 0xcc, 0x85 }
       )
 
       -- Combining characters U+0300, U+0301, U+0302, U+0303, U+0304, U+0305, U+0306
       eq(
-        { '\x7f\xcc\x80\xcc\x81\xcc\x82\xcc\x83\xcc\x84\xcc\x85\xcc\x86', 0x7f },
+        { '\x29\xcc\x80\xcc\x81\xcc\x82\xcc\x83\xcc\x84\xcc\x85\xcc\x86', 0x29 },
         test_seq {
-          0x7f,
+          0x29,
           0xcc,
           0x80,
           0xcc,
@@ -175,18 +196,18 @@ describe('mbyte', function()
 
       -- Only three following combining characters U+0300, U+0301, U+0302
       eq(
-        { '\x7f\xcc\x80\xcc\x81\xcc\x82', 0x7f },
-        test_seq { 0x7f, 0xcc, 0x80, 0xcc, 0x81, 0xcc, 0x82, 0xc2, 0x80, 0xcc, 0x84, 0xcc, 0x85 }
+        { '\x29\xcc\x80\xcc\x81\xcc\x82', 0x29 },
+        test_seq { 0x29, 0xcc, 0x80, 0xcc, 0x81, 0xcc, 0x82, 0xc2, 0x80, 0xcc, 0x84, 0xcc, 0x85 }
       )
 
       -- No UTF-8 sequence
       eq({ '', 0xc2 }, test_seq { 0xc2, 0x7f, 0xcc, 0x80, 0x80 })
       -- No following UTF-8 character
-      eq({ '\xc2\x80', 0x80 }, test_seq { 0xc2, 0x80, 0xcc, 0xcc, 0x80 })
+      eq({ '\xc2\xbc', 0xbc }, test_seq { 0xc2, 0xbc, 0xcc, 0xcc, 0x80 })
       -- Combining character U+0301
-      eq({ '\xc2\x80\xcc\x81', 0x80 }, test_seq { 0xc2, 0x80, 0xcc, 0x81, 0x7f })
+      eq({ '\xc2\xbc\xcc\x81', 0xbc }, test_seq { 0xc2, 0xbc, 0xcc, 0x81, 0x7f })
       -- Combining character U+0301
-      eq({ '\xc2\x80\xcc\x81', 0x80 }, test_seq { 0xc2, 0x80, 0xcc, 0x81, 0xcc })
+      eq({ '\xc2\xbc\xcc\x81', 0xbc }, test_seq { 0xc2, 0xbc, 0xcc, 0x81, 0xcc })
 
       -- One UTF-8 character
       eq({ '\xf4\x80\x80\x80', 0x100000 }, test_seq { 0xf4, 0x80, 0x80, 0x80, 0x7f })
@@ -205,8 +226,6 @@ describe('mbyte', function()
   end)
 
   describe('utf_cp_bounds_len', function()
-    local to_cstr = t.to_cstr
-
     local tests = {
       {
         name = 'for valid string',
@@ -273,4 +292,52 @@ describe('mbyte', function()
       eq(expected_offsets, { b = b_offsets, e = e_offsets })
     end)
   end)
+
+  itp('utf_head_off', function()
+    local function check(str, expected_glyphs)
+      local len = #str
+      local cstr = to_cstr(str)
+      local breaks = { 0 } -- SOT
+      local pos = 0
+      local mb_glyphs = {}
+      while pos < len do
+        local clen = lib.utfc_ptr2len(cstr + pos)
+        ok(clen > 0) -- otherwise we get stuck
+        if clen > 1 then
+          table.insert(mb_glyphs, string.sub(str, pos + 1, pos + clen))
+        end
+        pos = pos + clen
+        table.insert(breaks, pos)
+      end
+      eq(breaks[#breaks], len) -- include EOT as break
+      -- we could also send in breaks, but this is more human readable
+      eq(mb_glyphs, expected_glyphs)
+
+      for i = 1, #breaks - 1 do
+        local start, next = breaks[i], breaks[i + 1]
+
+        for p = start, next - 1 do
+          eq(p - start, lib.utf_head_off(cstr, cstr + p))
+        end
+      end
+      eq(0, lib.utf_head_off(cstr, cstr + len)) -- NUL byte is safe
+    end
+    -- stylua doesn't like ZWJ chars..
+    -- stylua: ignore start
+    check('hej och hå 🧑‍🌾!', { 'å', '🧑‍🌾' })
+    -- emoji only (various kinds of combinations, use g8 to see them)
+    check("🏳️‍⚧️🧑‍🌾❤️😂🏴‍☠️", {"🏳️‍⚧️", "🧑‍🌾", "❤️", "😂", "🏴‍☠️"})
+    check('🏳️‍⚧️xy🧑‍🌾\r❤️😂å🏴‍☠️€', { '🏳️‍⚧️', '🧑‍🌾', '❤️', '😂', 'å', '🏴‍☠️', '€' })
+
+    check('🇦🅱️ 🇦🇽 🇦🇨🇦 🇲🇽🇹🇱',{'🇦', '🅱️', '🇦🇽', '🇦🇨', '🇦', '🇲🇽', '🇹🇱'})
+    check('🏴󠁧󠁢󠁳󠁣󠁴󠁿🏴󠁧󠁢󠁷󠁬󠁳󠁿', {'🏴󠁧󠁢󠁳󠁣󠁴󠁿', '🏴󠁧󠁢󠁷󠁬󠁳󠁿'})
+
+    lib.p_arshape = true -- default
+    check('سلام', { 'س', 'لا', 'م' })
+    lib.p_arshape = false
+    check('سلام', { 'س', 'ل', 'ا', 'م' })
+
+    check('L̓̉̑̒̌̚ơ̗̌̒̄̀ŕ̈̈̎̐̕è̇̅̄̄̐m̖̟̟̅̄̚', {'L̓̉̑̒̌̚', 'ơ̗̌̒̄̀', 'ŕ̈̈̎̐̕', 'è̇̅̄̄̐', 'm̖̟̟̅̄̚'})
+    -- stylua: ignore end
+  end)
 end)