vim-patch:9.1.0936: cannot highlight completed text

Problem:  cannot highlight completed text
Solution: (optionally) highlight auto-completed text using the
          ComplMatchIns highlight group (glepnir)

closes: vim/vim#16173

https://github.com/vim/vim/commit/6a38aff218f5b99a1aed7edaa357df24b9092734

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

7 files changed, 101 insertions, 13 deletions

diff --git a/runtime/colors/vim.lua b/runtime/colors/vim.lua
index 5b9309ab38..dd3e83c653 100644
--- a/runtime/colors/vim.lua
+++ b/runtime/colors/vim.lua
@@ -60,6 +60,7 @@ hi('PmenuMatch',     { link = 'Pmenu' })
 hi('PmenuMatchSel',  { link = 'PmenuSel' })
 hi('PmenuExtra',     { link = 'Pmenu' })
 hi('PmenuExtraSel',  { link = 'PmenuSel' })
+hi('ComplMatchIns',  { link = 'Normal' })
 hi('Substitute',     { link = 'Search' })
 hi('Whitespace',     { link = 'NonText' })
 hi('MsgSeparator',   { link = 'StatusLine' })
diff --git a/runtime/doc/news.txt b/runtime/doc/news.txt
index ad0835e80f..73704a143c 100644
--- a/runtime/doc/news.txt
+++ b/runtime/doc/news.txt
@@ -216,6 +216,7 @@ EDITOR
 • On Windows, filename arguments on the command-line prefixed with "~\" or
   "~/" are now expanded to the user's profile directory, not a relative path
   to a literal "~" directory.
+• |hl-ComplMatchIns| shows matched text of the currently inserted completion.
 • |hl-PmenuMatch| and |hl-PmenuMatchSel| show matched text in completion popup.
 
 EVENTS
diff --git a/runtime/doc/syntax.txt b/runtime/doc/syntax.txt
index df4d0f7260..f5183e3247 100644
--- a/runtime/doc/syntax.txt
+++ b/runtime/doc/syntax.txt
@@ -5243,6 +5243,8 @@ PmenuMatch	Popup menu: Matched text in normal item. Combined with
 							*hl-PmenuMatchSel*
 PmenuMatchSel	Popup menu: Matched text in selected item. Combined with
 		|hl-PmenuMatch| and |hl-PmenuSel|.
+							*hl-ComplMatchIns*
+ComplMatchIns	Matched text of the currently inserted completion.
 							*hl-Question*
 Question	|hit-enter| prompt and yes/no questions.
 							*hl-QuickFixLine*
diff --git a/src/nvim/drawline.c b/src/nvim/drawline.c
index b8f21d7454..e15296572b 100644
--- a/src/nvim/drawline.c
+++ b/src/nvim/drawline.c
@@ -31,6 +31,7 @@
 #include "nvim/highlight_defs.h"
 #include "nvim/highlight_group.h"
 #include "nvim/indent.h"
+#include "nvim/insexpand.h"
 #include "nvim/mark_defs.h"
 #include "nvim/marktree_defs.h"
 #include "nvim/match.h"
@@ -934,6 +935,7 @@ int win_line(win_T *wp, linenr_T lnum, int startrow, int endrow, int col_rows, s
   colnr_T vcol_prev = -1;             // "wlv.vcol" of previous character
   ScreenGrid *grid = &wp->w_grid;     // grid specific to the window
 
+  const bool in_curline = wp == curwin && lnum == curwin->w_cursor.lnum;
   const bool has_fold = foldinfo.fi_level != 0 && foldinfo.fi_lines > 0;
   const bool has_foldtext = has_fold && *wp->w_p_fdt != NUL;
 
@@ -954,6 +956,7 @@ int win_line(win_T *wp, linenr_T lnum, int startrow, int endrow, int col_rows, s
   int vi_attr = 0;                      // attributes for Visual and incsearch highlighting
   int area_attr = 0;                    // attributes desired by highlighting
   int search_attr = 0;                  // attributes desired by 'hlsearch'
+  int ins_match_attr = 0;               // attributes desired by PmenuMatch
   int vcol_save_attr = 0;               // saved attr for 'cursorcolumn'
   int decor_attr = 0;                   // attributes desired by syntax and extmarks
   bool has_syntax = false;              // this buffer has syntax highl.
@@ -1117,7 +1120,7 @@ int win_line(win_T *wp, linenr_T lnum, int startrow, int endrow, int col_rows, s
       }
 
       // Check if the char under the cursor should be inverted (highlighted).
-      if (!highlight_match && lnum == curwin->w_cursor.lnum && wp == curwin
+      if (!highlight_match && in_curline
           && cursor_is_block_during_visual(*p_sel == 'e')) {
         noinvcur = true;
       }
@@ -2704,6 +2707,14 @@ int win_line(win_T *wp, linenr_T lnum, int startrow, int endrow, int col_rows, s
       vcol_prev = wlv.vcol;
     }
 
+    if (wlv.filler_todo <= 0
+        && (State & MODE_INSERT) && in_curline && ins_compl_active()) {
+      ins_match_attr = ins_compl_col_range_attr(wlv.col);
+      if (ins_match_attr > 0) {
+        wlv.char_attr = hl_combine_attr(wlv.char_attr, ins_match_attr);
+      }
+    }
+
     // Store character to be displayed.
     // Skip characters that are left of the screen for 'nowrap'.
     if (wlv.filler_todo > 0) {
diff --git a/src/nvim/highlight_group.c b/src/nvim/highlight_group.c
index f1f5f47630..636124a698 100644
--- a/src/nvim/highlight_group.c
+++ b/src/nvim/highlight_group.c
@@ -173,6 +173,7 @@ static const char *highlight_init_both[] = {
   "default link PmenuKind        Pmenu",
   "default link PmenuKindSel     PmenuSel",
   "default link PmenuSbar        Pmenu",
+  "default link ComplMatchIns    Normal",
   "default link Substitute       Search",
   "default link StatusLineTerm   StatusLine",
   "default link StatusLineTermNC StatusLineNC",
diff --git a/src/nvim/insexpand.c b/src/nvim/insexpand.c
index 2e3a2e39ac..5036ec5e45 100644
--- a/src/nvim/insexpand.c
+++ b/src/nvim/insexpand.c
@@ -256,6 +256,7 @@ static pos_T compl_startpos;
 static int compl_length = 0;
 static colnr_T compl_col = 0;           ///< column where the text starts
                                         ///< that is being completed
+static colnr_T compl_ins_end_col = 0;
 static char *compl_orig_text = NULL;    ///< text as it was before
                                         ///< completion started
 /// Undo information to restore extmarks for original text.
@@ -282,6 +283,11 @@ static size_t spell_bad_len = 0;   // length of located bad word
 
 static int compl_selected_item = -1;
 
+// "compl_match_array" points the currently displayed list of entries in the
+// popup menu.  It is NULL when there is no popup menu.
+static pumitem_T *compl_match_array = NULL;
+static int compl_match_arraysize;
+
 /// CTRL-X pressed in Insert mode.
 void ins_ctrl_x(void)
 {
@@ -943,6 +949,30 @@ static bool ins_compl_equal(compl_T *match, char *str, size_t len)
   return strncmp(match->cp_str, str, len) == 0;
 }
 
+/// when len is -1 mean use whole length of p otherwise part of p
+static void ins_compl_insert_bytes(char *p, int len)
+  FUNC_ATTR_NONNULL_ALL
+{
+  if (len == -1) {
+    len = (int)strlen(p);
+  }
+  assert(len >= 0);
+  ins_bytes_len(p, (size_t)len);
+  compl_ins_end_col = curwin->w_cursor.col - 1;
+}
+
+/// Checks if the column is within the currently inserted completion text
+/// column range. If it is, it returns a special highlight attribute.
+/// -1 mean normal item.
+int ins_compl_col_range_attr(int col)
+{
+  if (col >= compl_col && col < compl_ins_end_col) {
+    return syn_name2attr("ComplMatchIns");
+  }
+
+  return -1;
+}
+
 /// Reduce the longest common string for match "match".
 static void ins_compl_longest_match(compl_T *match)
 {
@@ -952,7 +982,7 @@ static void ins_compl_longest_match(compl_T *match)
 
     bool had_match = (curwin->w_cursor.col > compl_col);
     ins_compl_delete(false);
-    ins_bytes(compl_leader + get_compl_len());
+    ins_compl_insert_bytes(compl_leader + get_compl_len(), -1);
     ins_redraw(false);
 
     // When the match isn't there (to avoid matching itself) remove it
@@ -986,7 +1016,7 @@ static void ins_compl_longest_match(compl_T *match)
     *p = NUL;
     bool had_match = (curwin->w_cursor.col > compl_col);
     ins_compl_delete(false);
-    ins_bytes(compl_leader + get_compl_len());
+    ins_compl_insert_bytes(compl_leader + get_compl_len(), -1);
     ins_redraw(false);
 
     // When the match isn't there (to avoid matching itself) remove it
@@ -1058,11 +1088,6 @@ unsigned get_cot_flags(void)
   return curbuf->b_cot_flags != 0 ? curbuf->b_cot_flags : cot_flags;
 }
 
-/// "compl_match_array" points the currently displayed list of entries in the
-/// popup menu.  It is NULL when there is no popup menu.
-static pumitem_T *compl_match_array = NULL;
-static int compl_match_arraysize;
-
 /// Remove any popup menu.
 static void ins_compl_del_pum(void)
 {
@@ -1678,6 +1703,7 @@ void ins_compl_clear(void)
   compl_cont_status = 0;
   compl_started = false;
   compl_matches = 0;
+  compl_ins_end_col = 0;
   XFREE_CLEAR(compl_pattern);
   compl_patternlen = 0;
   XFREE_CLEAR(compl_leader);
@@ -1802,7 +1828,7 @@ static void ins_compl_new_leader(void)
 {
   ins_compl_del_pum();
   ins_compl_delete(true);
-  ins_bytes(compl_leader + get_compl_len());
+  ins_compl_insert_bytes(compl_leader + get_compl_len(), -1);
   compl_used_match = false;
 
   if (compl_started) {
@@ -2137,7 +2163,7 @@ static bool ins_compl_stop(const int c, const int prev_mode, bool retval)
       const int compl_len = get_compl_len();
       const int len = (int)strlen(p);
       if (len > compl_len) {
-        ins_bytes_len(p + compl_len, (size_t)(len - compl_len));
+        ins_compl_insert_bytes(p + compl_len, len - compl_len);
       }
     }
     restore_orig_extmarks();
@@ -3639,7 +3665,7 @@ void ins_compl_insert(bool in_compl_func)
   // Make sure we don't go over the end of the string, this can happen with
   // illegal bytes.
   if (compl_len < (int)strlen(compl_shown_match->cp_str)) {
-    ins_bytes(compl_shown_match->cp_str + compl_len);
+    ins_compl_insert_bytes(compl_shown_match->cp_str + compl_len, -1);
   }
   compl_used_match = !match_at_original_text(compl_shown_match);
 
@@ -3888,14 +3914,15 @@ static int ins_compl_next(bool allow_get_expansion, int count, bool insert_match
 
   // Insert the text of the new completion, or the compl_leader.
   if (compl_no_insert && !started) {
-    ins_bytes(compl_orig_text + get_compl_len());
+    ins_compl_insert_bytes(compl_orig_text + get_compl_len(), -1);
     compl_used_match = false;
     restore_orig_extmarks();
   } else if (insert_match) {
     if (!compl_get_longest || compl_used_match) {
       ins_compl_insert(in_compl_func);
     } else {
-      ins_bytes(compl_leader + get_compl_len());
+      assert(compl_leader != NULL);
+      ins_compl_insert_bytes(compl_leader + get_compl_len(), -1);
     }
     if (!strcmp(compl_curr_match->cp_str, compl_orig_text)) {
       restore_orig_extmarks();
diff --git a/test/old/testdir/test_popup.vim b/test/old/testdir/test_popup.vim
index a24e133ce6..4f5b769ace 100644
--- a/test/old/testdir/test_popup.vim
+++ b/test/old/testdir/test_popup.vim
@@ -1713,4 +1713,49 @@ func Test_pum_keep_select()
   call StopVimInTerminal(buf)
 endfunc
 
+func Test_pum_matchins_higlight()
+  CheckScreendump
+  let lines =<< trim END
+    func Omni_test(findstart, base)
+      if a:findstart
+        return col(".")
+      endif
+      return [#{word: "foo"}, #{word: "bar"}, #{word: "你好"}]
+    endfunc
+    set omnifunc=Omni_test
+    hi ComplMatchIns ctermfg=red
+  END
+  call writefile(lines, 'Xscript', 'D')
+  let buf = RunVimInTerminal('-S Xscript', {})
+
+  call TermWait(buf)
+  call term_sendkeys(buf, "S\<C-X>\<C-O>")
+  call VerifyScreenDump(buf, 'Test_pum_matchins_01', {})
+  call term_sendkeys(buf, "\<C-E>\<Esc>")
+
+  call TermWait(buf)
+  call term_sendkeys(buf, "S\<C-X>\<C-O>\<C-N>")
+  call VerifyScreenDump(buf, 'Test_pum_matchins_02', {})
+  call term_sendkeys(buf, "\<C-E>\<Esc>")
+
+  call TermWait(buf)
+  call term_sendkeys(buf, "S\<C-X>\<C-O>\<C-N>\<C-N>")
+  call VerifyScreenDump(buf, 'Test_pum_matchins_03', {})
+  call term_sendkeys(buf, "\<C-E>\<Esc>")
+
+  " restore after accept
+  call TermWait(buf)
+  call term_sendkeys(buf, "S\<C-X>\<C-O>\<C-Y>")
+  call VerifyScreenDump(buf, 'Test_pum_matchins_04', {})
+  call term_sendkeys(buf, "\<C-E>\<Esc>")
+
+  " restore after cancel completion
+  call TermWait(buf)
+  call term_sendkeys(buf, "S\<C-X>\<C-O>\<Space>")
+  call VerifyScreenDump(buf, 'Test_pum_matchins_05', {})
+  call term_sendkeys(buf, "\<C-E>\<Esc>")
+
+  call StopVimInTerminal(buf)
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab