fix(display): wrong cursor column with 'concealcursor' = "n" and virt_text (#33218)

Problem:  Inline virtual text placed in a decor provider callback
          invalidates `w_virtcol`, which must be valid for `win_line()`.
Solution: Call `validate_virtcol()` after "line" decor provider callbacks.

2 files changed, 29 insertions, 1 deletions

diff --git a/src/nvim/drawline.c b/src/nvim/drawline.c
index 43d9f67b5c..79cfc1ab2f 100644
--- a/src/nvim/drawline.c
+++ b/src/nvim/drawline.c
@@ -1163,7 +1163,8 @@ int win_line(win_T *wp, linenr_T lnum, int startrow, int endrow, int col_rows, b
       }
     }
 
-    decor_providers_invoke_line(wp, lnum - 1);
+    decor_providers_invoke_line(wp, lnum - 1);  // may invalidate wp->w_virtcol
+    validate_virtcol(wp);
 
     has_decor = decor_redraw_line(wp, lnum - 1, &decor_state);
 
diff --git a/test/functional/ui/decorations_spec.lua b/test/functional/ui/decorations_spec.lua
index 06bb5a14c9..307f750175 100644
--- a/test/functional/ui/decorations_spec.lua
+++ b/test/functional/ui/decorations_spec.lua
@@ -811,6 +811,33 @@ describe('decorations providers', function()
                                               |
     ]])
   end)
+
+  it('inline virt_text does not result in wrong cursor column #33153', function()
+    insert("line1 with a lot of text\nline2 with a lot of text")
+    setup_provider([[
+      _G.do_win = false
+      vim.keymap.set('n', 'f', function()
+        _G.do_win = true
+        vim.cmd('redraw!')
+      end)
+      vim.o.concealcursor = 'n'
+      function on_do(event)
+        if event == 'win' and _G.do_win then
+          vim.api.nvim_buf_set_extmark(0, ns1, 1, 0, {
+            virt_text = { { 'virt_text ' } },
+            virt_text_pos = 'inline'
+          })
+        end
+      end
+    ]])
+    feed('f')
+    screen:expect([[
+      line1 with a lot of text                |
+      virt_text line2 with a lot of tex^t      |
+      {1:~                                       }|*5
+                                              |
+    ]])
+  end)
 end)
 
 describe('decoration_providers', function()