fix(drawline): fix missing Visual hl on double-width fold char (#24308)

2 files changed, 201 insertions, 19 deletions

diff --git a/src/nvim/drawline.c b/src/nvim/drawline.c
index 7bd0f67014..6bf9dc845d 100644
--- a/src/nvim/drawline.c
+++ b/src/nvim/drawline.c
@@ -1805,9 +1805,11 @@ int win_line(win_T *wp, linenr_T lnum, int startrow, int endrow, bool number_onl
         && (area_highlighting || spv->spv_has_spell || extra_check)) {
       // handle Visual or match highlighting in this line
       if (wlv.vcol == wlv.fromcol
-          || (wlv.vcol + 1 == wlv.fromcol && wlv.n_extra == 0
-              && utf_ptr2cells(ptr) > 1)
-          || ((int)vcol_prev == fromcol_prev
+          || (wlv.vcol + 1 == wlv.fromcol
+              && ((wlv.n_extra == 0 && utf_ptr2cells(ptr) > 1)
+                  || (wlv.n_extra > 0 && wlv.p_extra != NULL
+                      && utf_ptr2cells(wlv.p_extra) > 1)))
+          || (vcol_prev == fromcol_prev
               && vcol_prev < wlv.vcol               // not at margin
               && wlv.vcol < wlv.tocol)) {
         area_attr = vi_attr;                    // start highlighting
diff --git a/test/functional/ui/fold_spec.lua b/test/functional/ui/fold_spec.lua
index d3119ccc42..f00fba331e 100644
--- a/test/functional/ui/fold_spec.lua
+++ b/test/functional/ui/fold_spec.lua
@@ -2509,18 +2509,18 @@ describe("folded lines", function()
     it('Folded and Visual highlights are combined #19691', function()
       command('hi! Visual guibg=Red')
       insert([[
-        " foo
-        " {{{1
+        " foofoofoofoofoofoo
+        " 口 {{{1
         set nocp
         " }}}1
-        " bar
-        " {{{1
+        " barbarbarbarbarbar
+        " 口 {{{1
         set foldmethod=marker
         " }}}1
-        " baz]])
+        " bazbazbazbazbazbaz]])
       feed('gg')
       command('source')
-      feed('<C-V>G3l')
+      feed('<C-V>G15l')
       if multigrid then
         screen:expect([[
         ## grid 1
@@ -2533,11 +2533,11 @@ describe("folded lines", function()
           [2:---------------------------------------------]|
           [3:---------------------------------------------]|
         ## grid 2
-          {14:" fo}o                                        |
-          {15:+-- }{5: 3 lines: "······························}|
-          {14:" ba}r                                        |
-          {15:+-- }{5: 3 lines: "······························}|
-          {14:" b}^az                                        |
+          {14:" foofoofoofoofo}ofoo                         |
+          {15:+--  3 lines: " }{5:口···························}|
+          {14:" barbarbarbarba}rbar                         |
+          {15:+--  3 lines: " }{5:口···························}|
+          {14:" bazbazbazbazb}^azbaz                         |
           {1:~                                            }|
           {1:~                                            }|
         ## grid 3
@@ -2545,11 +2545,191 @@ describe("folded lines", function()
         ]])
       else
         screen:expect([[
-          {14:" fo}o                                        |
-          {15:+-- }{5: 3 lines: "······························}|
-          {14:" ba}r                                        |
-          {15:+-- }{5: 3 lines: "······························}|
-          {14:" b}^az                                        |
+          {14:" foofoofoofoofo}ofoo                         |
+          {15:+--  3 lines: " }{5:口···························}|
+          {14:" barbarbarbarba}rbar                         |
+          {15:+--  3 lines: " }{5:口···························}|
+          {14:" bazbazbazbazb}^azbaz                         |
+          {1:~                                            }|
+          {1:~                                            }|
+          {11:-- VISUAL BLOCK --}                           |
+        ]])
+      end
+
+      feed('l')
+      if multigrid then
+        screen:expect([[
+        ## grid 1
+          [2:---------------------------------------------]|
+          [2:---------------------------------------------]|
+          [2:---------------------------------------------]|
+          [2:---------------------------------------------]|
+          [2:---------------------------------------------]|
+          [2:---------------------------------------------]|
+          [2:---------------------------------------------]|
+          [3:---------------------------------------------]|
+        ## grid 2
+          {14:" foofoofoofoofoo}foo                         |
+          {15:+--  3 lines: " 口}{5:···························}|
+          {14:" barbarbarbarbar}bar                         |
+          {15:+--  3 lines: " 口}{5:···························}|
+          {14:" bazbazbazbazba}^zbaz                         |
+          {1:~                                            }|
+          {1:~                                            }|
+        ## grid 3
+          {11:-- VISUAL BLOCK --}                           |
+        ]])
+      else
+        screen:expect([[
+          {14:" foofoofoofoofoo}foo                         |
+          {15:+--  3 lines: " 口}{5:···························}|
+          {14:" barbarbarbarbar}bar                         |
+          {15:+--  3 lines: " 口}{5:···························}|
+          {14:" bazbazbazbazba}^zbaz                         |
+          {1:~                                            }|
+          {1:~                                            }|
+          {11:-- VISUAL BLOCK --}                           |
+        ]])
+      end
+
+      feed('l')
+      if multigrid then
+        screen:expect([[
+        ## grid 1
+          [2:---------------------------------------------]|
+          [2:---------------------------------------------]|
+          [2:---------------------------------------------]|
+          [2:---------------------------------------------]|
+          [2:---------------------------------------------]|
+          [2:---------------------------------------------]|
+          [2:---------------------------------------------]|
+          [3:---------------------------------------------]|
+        ## grid 2
+          {14:" foofoofoofoofoof}oo                         |
+          {15:+--  3 lines: " 口}{5:···························}|
+          {14:" barbarbarbarbarb}ar                         |
+          {15:+--  3 lines: " 口}{5:···························}|
+          {14:" bazbazbazbazbaz}^baz                         |
+          {1:~                                            }|
+          {1:~                                            }|
+        ## grid 3
+          {11:-- VISUAL BLOCK --}                           |
+        ]])
+      else
+        screen:expect([[
+          {14:" foofoofoofoofoof}oo                         |
+          {15:+--  3 lines: " 口}{5:···························}|
+          {14:" barbarbarbarbarb}ar                         |
+          {15:+--  3 lines: " 口}{5:···························}|
+          {14:" bazbazbazbazbaz}^baz                         |
+          {1:~                                            }|
+          {1:~                                            }|
+          {11:-- VISUAL BLOCK --}                           |
+        ]])
+      end
+
+      feed('2l')
+      if multigrid then
+        screen:expect([[
+        ## grid 1
+          [2:---------------------------------------------]|
+          [2:---------------------------------------------]|
+          [2:---------------------------------------------]|
+          [2:---------------------------------------------]|
+          [2:---------------------------------------------]|
+          [2:---------------------------------------------]|
+          [2:---------------------------------------------]|
+          [3:---------------------------------------------]|
+        ## grid 2
+          {14:" foofoofoofoofoofoo}                         |
+          {15:+--  3 lines: " 口··}{5:·························}|
+          {14:" barbarbarbarbarbar}                         |
+          {15:+--  3 lines: " 口··}{5:·························}|
+          {14:" bazbazbazbazbazba}^z                         |
+          {1:~                                            }|
+          {1:~                                            }|
+        ## grid 3
+          {11:-- VISUAL BLOCK --}                           |
+        ]])
+      else
+        screen:expect([[
+          {14:" foofoofoofoofoofoo}                         |
+          {15:+--  3 lines: " 口··}{5:·························}|
+          {14:" barbarbarbarbarbar}                         |
+          {15:+--  3 lines: " 口··}{5:·························}|
+          {14:" bazbazbazbazbazba}^z                         |
+          {1:~                                            }|
+          {1:~                                            }|
+          {11:-- VISUAL BLOCK --}                           |
+        ]])
+      end
+
+      feed('O16l')
+      if multigrid then
+        screen:expect([[
+        ## grid 1
+          [2:---------------------------------------------]|
+          [2:---------------------------------------------]|
+          [2:---------------------------------------------]|
+          [2:---------------------------------------------]|
+          [2:---------------------------------------------]|
+          [2:---------------------------------------------]|
+          [2:---------------------------------------------]|
+          [3:---------------------------------------------]|
+        ## grid 2
+          " foofoofoofoofo{14:ofoo}                         |
+          {5:+--  3 lines: " }{15:口··}{5:·························}|
+          " barbarbarbarba{14:rbar}                         |
+          {5:+--  3 lines: " }{15:口··}{5:·························}|
+          " bazbazbazbazba^z{14:baz}                         |
+          {1:~                                            }|
+          {1:~                                            }|
+        ## grid 3
+          {11:-- VISUAL BLOCK --}                           |
+        ]])
+      else
+        screen:expect([[
+          " foofoofoofoofo{14:ofoo}                         |
+          {5:+--  3 lines: " }{15:口··}{5:·························}|
+          " barbarbarbarba{14:rbar}                         |
+          {5:+--  3 lines: " }{15:口··}{5:·························}|
+          " bazbazbazbazba^z{14:baz}                         |
+          {1:~                                            }|
+          {1:~                                            }|
+          {11:-- VISUAL BLOCK --}                           |
+        ]])
+      end
+
+      feed('l')
+      if multigrid then
+        screen:expect([[
+        ## grid 1
+          [2:---------------------------------------------]|
+          [2:---------------------------------------------]|
+          [2:---------------------------------------------]|
+          [2:---------------------------------------------]|
+          [2:---------------------------------------------]|
+          [2:---------------------------------------------]|
+          [2:---------------------------------------------]|
+          [3:---------------------------------------------]|
+        ## grid 2
+          " foofoofoofoofoo{14:foo}                         |
+          {5:+--  3 lines: " }{15:口··}{5:·························}|
+          " barbarbarbarbar{14:bar}                         |
+          {5:+--  3 lines: " }{15:口··}{5:·························}|
+          " bazbazbazbazbaz^b{14:az}                         |
+          {1:~                                            }|
+          {1:~                                            }|
+        ## grid 3
+          {11:-- VISUAL BLOCK --}                           |
+        ]])
+      else
+        screen:expect([[
+          " foofoofoofoofoo{14:foo}                         |
+          {5:+--  3 lines: " }{15:口··}{5:·························}|
+          " barbarbarbarbar{14:bar}                         |
+          {5:+--  3 lines: " }{15:口··}{5:·························}|
+          " bazbazbazbazbaz^b{14:az}                         |
           {1:~                                            }|
           {1:~                                            }|
           {11:-- VISUAL BLOCK --}                           |