vim-patch:9.1.1296: completion: incorrect truncation logic

Problem:  completion: incorrect truncation logic (after: v9.1.1284)
Solution: replace string allocation with direct screen rendering and
          fixe RTL/LTR truncation calculations (glepnir)

closes: vim/vim#17081

d4dbf822dc

Co-authored-by: glepnir <glephunter@gmail.com>

runtime/doc/options.txt

@@ -2642,6 +2642,7 @@ A jump table for the options with a short description can be found at |Q_op|.
 	  lastline	'@'		'display' contains lastline/truncate
 	  trunc		'>'		truncated text in the
 					|ins-completion-menu|.
+	  truncrl	'<'		same as "trunc' in 'rightleft' mode
 
 	Any one that is omitted will fall back to the default.
 
@@ -2681,6 +2682,7 @@ A jump table for the options with a short description can be found at |Q_op|.
 	  lastline	NonText			|hl-NonText|
 	  trunc		one of the many Popup menu highlighting groups like
 			|hl-PmenuSel|
+	  truncrl	same as "trunc"
 
 					*'findfunc'* *'ffu'* *E1514*
 'findfunc' 'ffu'	string	(default "")

runtime/lua/vim/_meta/options.lua

@@ -2334,6 +2334,7 @@ vim.bo.ft = vim.bo.filetype
 ---   lastline	'@'		'display' contains lastline/truncate
 ---   trunc		'>'		truncated text in the
 --- 				`ins-completion-menu`.
+---   truncrl	'<'		same as "trunc' in 'rightleft' mode
 ---
 --- Any one that is omitted will fall back to the default.
 ---
@@ -2376,6 +2377,7 @@ vim.bo.ft = vim.bo.filetype
 ---   lastline	NonText			`hl-NonText`
 ---   trunc		one of the many Popup menu highlighting groups like
 --- 		`hl-PmenuSel`
+---   truncrl	same as "trunc"
 ---
 --- @type string
 vim.o.fillchars = ""

src/nvim/buffer_defs.h

@@ -1057,6 +1057,7 @@ typedef struct {
   schar_T eob;
   schar_T lastline;
   schar_T trunc;
+  schar_T truncrl;
 } fcs_chars_T;
 
 /// Structure which contains all information that belongs to a window.

src/nvim/options.lua

@@ -3062,6 +3062,7 @@ local options = {
           lastline	'@'		'display' contains lastline/truncate
           trunc		'>'		truncated text in the
         				|ins-completion-menu|.
+          truncrl	'<'		same as "trunc' in 'rightleft' mode
 
         Any one that is omitted will fall back to the default.
 
@@ -3101,6 +3102,7 @@ local options = {
           lastline	NonText			|hl-NonText|
           trunc		one of the many Popup menu highlighting groups like
         		|hl-PmenuSel|
+          truncrl	same as "trunc"
       ]=],
       expand_cb = 'expand_set_chars_option',
       full_name = 'fillchars',

src/nvim/optionstr.c

@@ -2133,6 +2133,7 @@ static const struct chars_tab fcs_tab[] = {
   CHARSTAB_ENTRY(&fcs_chars.eob,        "eob",       "~", NULL),
   CHARSTAB_ENTRY(&fcs_chars.lastline,   "lastline",  "@", NULL),
   CHARSTAB_ENTRY(&fcs_chars.trunc,      "trunc",     ">", NULL),
+  CHARSTAB_ENTRY(&fcs_chars.truncrl,    "truncrl",   "<", NULL),
 };
 
 static lcs_chars_T lcs_chars;

src/nvim/popupmenu.c

@@ -577,7 +577,8 @@ void pum_redraw(void)
   int thumb_pos = 0;
   int thumb_height = 1;
   int n;
-  schar_T fcs_trunc = curwin->w_p_fcs_chars.trunc;
+  const schar_T fcs_trunc = pum_rl ? curwin->w_p_fcs_chars.truncrl
+                                   : curwin->w_p_fcs_chars.trunc;
 
   //                         "word"   "kind"   "extra text"
   const hlf_T hlfsNorm[3] = { HLF_PNI, HLF_PNK, HLF_PNX };
@@ -720,7 +721,9 @@ void pum_redraw(void)
             char *rt = reverse_text(st);
             char *rt_start = rt;
             int cells = (int)mb_string2cells(rt);
-            if (pum_width == p_pmw && totwidth + 1 + cells >= pum_width) {
+            if (pum_width == p_pmw
+                && (pum_width - totwidth < cells
+                    || (j + 1 < 3 && pum_get_item(idx, order[j + 1]) != NULL))) {
               need_fcs_trunc = true;
             }
 
@@ -749,7 +752,9 @@ void pum_redraw(void)
             grid_col -= width;
           } else {
             int cells = (int)mb_string2cells(st);
-            if (pum_width == p_pmw && totwidth + 1 + cells >= pum_width) {
+            if (pum_width == p_pmw
+                && (pum_width - totwidth < cells
+                    || (j + 1 < 3 && pum_get_item(idx, order[j + 1]) != NULL))) {
               need_fcs_trunc = true;
             }
 
@@ -818,8 +823,7 @@ void pum_redraw(void)
       const int lcol = col_off - pum_width + 1;
       grid_line_fill(lcol, grid_col + 1, schar_from_ascii(' '), orig_attr);
       if (need_fcs_trunc) {
-        linebuf_char[lcol] = fcs_trunc != NUL && fcs_trunc != schar_from_ascii('>')
+        linebuf_char[lcol] = fcs_trunc != NUL ? fcs_trunc : schar_from_ascii('<');
-                             ? fcs_trunc : schar_from_ascii('<');
         if (pum_width > 1 && linebuf_char[lcol + 1] == NUL) {
           linebuf_char[lcol + 1] = schar_from_ascii(' ');
         }

test/functional/ui/popupmenu_spec.lua

@@ -5891,7 +5891,7 @@ describe('builtin popupmenu', function()
         ## grid 4
           {s:123456789>}|
           {n:一二三四 >}|
-          {n:abcdefghi>}|
+          {n:abcdefghij}|
           {n:上下左右  }|
         ]],
           float_pos = { [4] = { -1, 'NW', 2, 1, 0, false, 100, 1, 1, 0 } },
@@ -5901,7 +5901,7 @@ describe('builtin popupmenu', function()
           123456789_123456789_123456789_^                              |
           {s:123456789>}{1:                                                  }|
           {n:一二三四 >}{1:                                                  }|
-          {n:abcdefghi>}{1:                                                  }|
+          {n:abcdefghij}{1:                                                  }|
           {n:上下左右  }{1:                                                  }|
           {1:~                                                           }|*2
           {2:-- Omni completion (^O^N^P) }{5:match 1 of 4}                    |
@@ -5925,7 +5925,7 @@ describe('builtin popupmenu', function()
         ## grid 4
           {s:<987654321}|
           {n:< 四三二一}|
-          {n:<ihgfedcba}|
+          {n:jihgfedcba}|
           {n:  右左下上}|
         ]],
           float_pos = { [4] = { -1, 'NW', 2, 1, 50, false, 100, 1, 1, 50 } },
@@ -5935,7 +5935,7 @@ describe('builtin popupmenu', function()
                                        ^ _987654321_987654321_987654321|
           {1:                                                  }{s:<987654321}|
           {1:                                                  }{n:< 四三二一}|
-          {1:                                                  }{n:<ihgfedcba}|
+          {1:                                                  }{n:jihgfedcba}|
           {1:                                                  }{n:  右左下上}|
           {1:                                                           ~}|*2
           {2:-- Omni completion (^O^N^P) }{5:match 1 of 4}                    |
@@ -6207,7 +6207,7 @@ describe('builtin popupmenu', function()
       end
       feed('<Esc>')
 
-      command('set fcs+=trunc:…')
+      command('set fcs+=truncrl:…')
       feed('S<C-X><C-O>')
       if multigrid then
         screen:expect({

test/old/testdir/test_popup.vim

@@ -2132,7 +2132,7 @@ func Test_pum_maxwidth_multibyte()
     call VerifyScreenDump(buf, 'Test_pum_maxwidth_16', {'rows': 8})
     call term_sendkeys(buf, "\<ESC>")
 
-    call term_sendkeys(buf, ":set fcs+=trunc:…\<CR>")
+    call term_sendkeys(buf, ":set fcs+=truncrl:…\<CR>")
     call term_sendkeys(buf, "S\<C-X>\<C-O>")
     call VerifyScreenDump(buf, 'Test_pum_maxwidth_17', {'rows': 8})
     call term_sendkeys(buf, "\<ESC>")