vim-patch:8.1.1110: composing chars on space wrong when 'listchars' is set

Problem:    Composing chars on space wrong when 'listchars' is set.
Solution:   Do not use "space" and "nbsp" entries of 'listchars' when there is
            a composing character.  (Yee Cheng Chin, closes vim/vim#4197)
https://github.com/vim/vim/commit/e5e4e22c1c15c8c22b14935affe969569acc8df9

2 files changed, 60 insertions, 29 deletions

diff --git a/src/nvim/screen.c b/src/nvim/screen.c
index 5ce8e0b348..1df5d6e8ef 100644
--- a/src/nvim/screen.c
+++ b/src/nvim/screen.c
@@ -3580,29 +3580,31 @@ static int win_line(win_T *wp, linenr_T lnum, int startrow, int endrow, bool noc
           }
         }
 
-        // 'list': change char 160 to 'nbsp' and space to 'space'.
-        if (wp->w_p_list) {
-          if ((c == 160 || (mb_utf8 && (mb_c == 160 || mb_c == 0x202f)))
-              && wp->w_p_lcs_chars.nbsp) {
-            c = wp->w_p_lcs_chars.nbsp;
-            mb_c = c;
-            if (utf_char2len(c) > 1) {
-              mb_utf8 = true;
-              u8cc[0] = 0;
-              c = 0xc0;
-            } else {
-              mb_utf8 = false;
-            }
-          } else if (c == ' '
-                     && wp->w_p_lcs_chars.space
-                     && ptr - line >= leadcol
-                     && ptr - line <= trailcol) {
-            c = wp->w_p_lcs_chars.space;
-            if (mb_utf8 == false) {
-              n_attr = 1;
-              extra_attr = win_hl_attr(wp, HLF_0);
-              saved_attr2 = char_attr;  // save current attr
-            }
+        // 'list': Change char 160 to 'nbsp' and space to 'space'.
+        // But not when the character is followed by a composing
+        // character (use mb_l to check that).
+        if (wp->w_p_list
+            && ((((c == 160 && mb_l == 1)
+                  || (mb_utf8
+                      && ((mb_c == 160 && mb_l == 2)
+                          || (mb_c == 0x202f && mb_l == 3))))
+                 && wp->w_p_lcs_chars.nbsp)
+                || (c == ' '
+                    && mb_l == 1
+                    && wp->w_p_lcs_chars.space
+                    && ptr - line >= leadcol
+                    && ptr - line <= trailcol))) {
+          c = (c == ' ') ? wp->w_p_lcs_chars.space : wp->w_p_lcs_chars.nbsp;
+          n_attr = 1;
+          extra_attr = win_hl_attr(wp, HLF_0);
+          saved_attr2 = char_attr;  // save current attr
+          mb_c = c;
+          if (utf_char2len(c) > 1) {
+            mb_utf8 = true;
+            u8cc[0] = 0;
+            c = 0xc0;
+          } else {
+            mb_utf8 = false;
           }
         }
 
diff --git a/src/nvim/testdir/test_listchars.vim b/src/nvim/testdir/test_listchars.vim
index 191e2afdf1..b75eec3d2e 100644
--- a/src/nvim/testdir/test_listchars.vim
+++ b/src/nvim/testdir/test_listchars.vim
@@ -182,6 +182,33 @@ func Test_listchars()
   set listchars& ff&
 endfunc
 
+" Test that unicode listchars characters get properly inserted
+func Test_listchars_unicode()
+  enew!
+  let oldencoding=&encoding
+  set encoding=utf-8
+  set ff=unix
+
+  set listchars=eol:⇔,space:␣,nbsp:≠,tab:←↔→
+  set list
+
+  let nbsp = nr2char(0xa0)
+  call append(0, [
+        \ "a\tb c".nbsp."d"
+        \ ])
+  let expected = [
+        \ 'a←↔↔↔↔↔→b␣c≠d⇔'
+        \ ]
+  redraw!
+  call cursor(1, 1)
+  call assert_equal(expected, ScreenLines(1, virtcol('$')))
+  let &encoding=oldencoding
+  enew!
+  set listchars& ff&
+endfunction
+
+" Tests that space characters following composing character won't get replaced
+" by listchars.
 func Test_listchars_composing()
   enew!
   let oldencoding=&encoding
@@ -189,18 +216,20 @@ func Test_listchars_composing()
   set ff=unix
   set list
 
-  set listchars=eol:$,space:_
+  set listchars=eol:$,space:_,nbsp:=
+  
+  let nbsp1 = nr2char(0xa0)
+  let nbsp2 = nr2char(0x202f)
   call append(0, [
-        \ "  \u3099	 \u309A"
+        \ "  \u3099\t \u309A".nbsp1.nbsp1."\u0302".nbsp2.nbsp2."\u0302",
         \ ])
   let expected = [
-        \ "_ \u3099^I \u309A$"
+        \ "_ \u3099^I \u309A=".nbsp1."\u0302=".nbsp2."\u0302$"
         \ ]
   redraw!
   call cursor(1, 1)
-  let got = ScreenLinesUtf8(1, virtcol('$'))
-  bw!
-  call assert_equal(expected, got)
+  call assert_equal(expected, ScreenLines(1, virtcol('$')))
   let &encoding=oldencoding
+  enew!
   set listchars& ff&
 endfunction