vim-patch:9.0.1067: in diff mode virtual text is highlighted incorrectly

Problem:    In diff mode virtual text is highlighted incorrectly. (Rick Howe)
Solution:   Do not use diff attributes for virtual text. (closes vim/vim#11714)

https://github.com/vim/vim/commit/d097af77797f030e0f29f9bbc298358a5addb2a5

Co-authored-by: Bram Moolenaar <Bram@vim.org>

2 files changed, 69 insertions, 12 deletions

diff --git a/src/nvim/drawline.c b/src/nvim/drawline.c
index 23b88413b1..84f0447ca6 100644
--- a/src/nvim/drawline.c
+++ b/src/nvim/drawline.c
@@ -105,9 +105,12 @@ typedef struct {
   int c_extra;               ///< extra chars, all the same
   int c_final;               ///< final char, mandatory if set
 
+  bool extra_for_extmark;
+
   // saved "extra" items for when draw_state becomes WL_LINE (again)
   int saved_n_extra;
   char *saved_p_extra;
+  bool saved_extra_for_extmark;
   int saved_c_extra;
   int saved_c_final;
   int saved_char_attr;
@@ -909,6 +912,7 @@ static void win_line_start(win_T *wp, winlinevars_T *wlv, bool save_extra)
     wlv->draw_state = WL_START;
     wlv->saved_n_extra = wlv->n_extra;
     wlv->saved_p_extra = wlv->p_extra;
+    wlv->saved_extra_for_extmark = wlv->extra_for_extmark;
     wlv->saved_c_extra = wlv->c_extra;
     wlv->saved_c_final = wlv->c_final;
     wlv->saved_char_attr = wlv->char_attr;
@@ -924,6 +928,7 @@ static void win_line_continue(winlinevars_T *wlv)
     // Continue item from end of wrapped line.
     wlv->n_extra = wlv->saved_n_extra;
     wlv->saved_n_extra = 0;
+    wlv->extra_for_extmark = wlv->saved_extra_for_extmark;
     wlv->c_extra = wlv->saved_c_extra;
     wlv->c_final = wlv->saved_c_final;
     wlv->p_extra = wlv->saved_p_extra;
@@ -1770,7 +1775,7 @@ int win_line(win_T *wp, linenr_T lnum, int startrow, int endrow, bool nochange,
           }
         }
 
-        if (wlv.n_extra == 0) {
+        if (wlv.n_extra == 0 || !wlv.extra_for_extmark) {
           reset_extra_attr = false;
         }
 
@@ -1778,6 +1783,7 @@ int win_line(win_T *wp, linenr_T lnum, int startrow, int endrow, bool nochange,
           VirtTextChunk vtc = kv_A(virt_inline, virt_inline_i);
           wlv.p_extra = vtc.text;
           wlv.n_extra = (int)strlen(wlv.p_extra);
+          wlv.extra_for_extmark = true;
           wlv.c_extra = NUL;
           wlv.c_final = NUL;
           wlv.extra_attr = vtc.hl_id ? syn_id2attr(vtc.hl_id) : 0;
@@ -1835,12 +1841,14 @@ int win_line(win_T *wp, linenr_T lnum, int startrow, int endrow, bool nochange,
       }
 
       if (wlv.diff_hlf != (hlf_T)0) {
+        // When there is extra text (eg: virtual text) it gets the
+        // diff highlighting for the line, but not for changed text.
         if (wlv.diff_hlf == HLF_CHD && ptr - line >= change_start
             && wlv.n_extra == 0) {
           wlv.diff_hlf = HLF_TXD;                   // changed text
         }
-        if (wlv.diff_hlf == HLF_TXD && ptr - line > change_end
-            && wlv.n_extra == 0) {
+        if (wlv.diff_hlf == HLF_TXD && ((ptr - line > change_end && wlv.n_extra == 0)
+                                        || (wlv.n_extra > 0 && wlv.extra_for_extmark))) {
           wlv.diff_hlf = HLF_CHD;                   // changed line
         }
         wlv.line_attr = win_hl_attr(wp, (int)wlv.diff_hlf);
@@ -1944,16 +1952,22 @@ int win_line(win_T *wp, linenr_T lnum, int startrow, int endrow, bool nochange,
 
       // Only restore search_attr and area_attr after "n_extra" in
       // the next screen line is also done.
-      if (wlv.n_extra <= 0 && wlv.saved_n_extra <= 0) {
-        if (search_attr == 0) {
-          search_attr = saved_search_attr;
-        }
-        if (area_attr == 0 && *ptr != NUL) {
-          area_attr = saved_area_attr;
+      if (wlv.n_extra <= 0) {
+        if (wlv.saved_n_extra <= 0) {
+          if (search_attr == 0) {
+            search_attr = saved_search_attr;
+          }
+          if (area_attr == 0 && *ptr != NUL) {
+            area_attr = saved_area_attr;
+          }
+
+          if (wlv.extra_for_extmark) {
+            // wlv.extra_attr should be used at this position but not
+            // any further.
+            reset_extra_attr = true;
+          }
         }
-        // wlv.extra_attr should be used at this position but not
-        // any further.
-        reset_extra_attr = true;
+        wlv.extra_for_extmark = false;
       }
     } else if (foldinfo.fi_lines > 0) {
       // skip writing the buffer line itself
diff --git a/test/functional/ui/decorations_spec.lua b/test/functional/ui/decorations_spec.lua
index 292743e21a..4579fad53f 100644
--- a/test/functional/ui/decorations_spec.lua
+++ b/test/functional/ui/decorations_spec.lua
@@ -648,6 +648,9 @@ describe('extmark decorations', function()
       [28] = {foreground = Screen.colors.SlateBlue};
       [29] = {background = Screen.colors.Yellow1};
       [30] = {reverse = true};
+      [31] = {foreground = Screen.colors.SlateBlue, background = Screen.colors.LightMagenta};
+      [32] = {bold = true, reverse = true};
+      [33] = {background = Screen.colors.Red1, bold = true}
     }
 
     ns = meths.create_namespace 'test'
@@ -1913,6 +1916,46 @@ bbbbbbb]])
                                                         |
       ]]}
   end)
+
+  it('in diff mode virtual text is highlighted correct', function()
+    insert([[
+    9000
+    0009
+    0009
+    9000
+    0009
+    ]])
+    command("set diff")
+    meths.buf_set_extmark(0, ns, 0, 1,
+      { virt_text = { { 'test', 'Special' } }, virt_text_pos = 'inline', right_gravity = false })
+    command("vnew")
+    insert([[
+    000
+    000
+    000
+    000
+    000
+    ]])
+    command("set diff")
+    feed('gg0')
+    screen:expect { grid = [[
+      {27:^000                      }│{33:9}{31:test}{27:000                }|
+      {27:000                      }│{27:000}{33:9}{27:                    }|
+      {27:000                      }│{27:000}{33:9}{27:                    }|
+      {27:000                      }│{33:9}{27:000                    }|
+      {27:000                      }│{27:000}{33:9}{27:                    }|
+                               │                        |
+      {1:~                        }│{1:~                       }|
+      {1:~                        }│{1:~                       }|
+      {1:~                        }│{1:~                       }|
+      {1:~                        }│{1:~                       }|
+      {1:~                        }│{1:~                       }|
+      {1:~                        }│{1:~                       }|
+      {1:~                        }│{1:~                       }|
+      {32:[No Name] [+]             }{30:[No Name] [+]           }|
+                                                        |
+      ]]}
+  end)
 end)
 
 describe('decorations: virtual lines', function()