fix(window): making float with title/footer non-float leaks memory (#30551)

5 files changed, 60 insertions, 27 deletions

diff --git a/src/nvim/api/win_config.c b/src/nvim/api/win_config.c
index b006f86a76..f63fdc5381 100644
--- a/src/nvim/api/win_config.c
+++ b/src/nvim/api/win_config.c
@@ -448,7 +448,7 @@ void nvim_win_set_config(Window window, Dict(win_config) *config, Error *err)
         }
       }
     }
-    win->w_config = fconfig;
+    merge_win_config(&win->w_config, fconfig);
 
     // If there's no "vertical" or "split" set, or if "split" is unchanged,
     // then we can just change the size of the window.
@@ -1312,12 +1312,7 @@ static bool parse_win_config(win_T *wp, Dict(win_config) *config, WinConfig *fco
   return true;
 
 fail:
-  if (wp == NULL || fconfig->title_chunks.items != wp->w_config.title_chunks.items) {
-    clear_virttext(&fconfig->title_chunks);
-  }
-  if (wp == NULL || fconfig->footer_chunks.items != wp->w_config.footer_chunks.items) {
-    clear_virttext(&fconfig->footer_chunks);
-  }
+  merge_win_config(fconfig, wp != NULL ? wp->w_config : WIN_CONFIG_INIT);
   return false;
 #undef HAS_KEY_X
 }
diff --git a/src/nvim/window.c b/src/nvim/window.c
index f7d5ee92cd..d3280a3478 100644
--- a/src/nvim/window.c
+++ b/src/nvim/window.c
@@ -798,6 +798,19 @@ int win_fdccol_count(win_T *wp)
   return fdc[0] - '0';
 }
 
+/// Merges two window configs, freeing replaced fields if necessary.
+void merge_win_config(WinConfig *dst, const WinConfig src)
+  FUNC_ATTR_NONNULL_ALL
+{
+  if (dst->title_chunks.items != src.title_chunks.items) {
+    clear_virttext(&dst->title_chunks);
+  }
+  if (dst->footer_chunks.items != src.footer_chunks.items) {
+    clear_virttext(&dst->footer_chunks);
+  }
+  *dst = src;
+}
+
 void ui_ext_win_position(win_T *wp, bool validate)
 {
   wp->w_pos_changed = false;
@@ -1288,7 +1301,7 @@ win_T *win_split_ins(int size, int flags, win_T *new_wp, int dir, frame_T *to_fl
     new_frame(wp);
 
     // non-floating window doesn't store float config or have a border.
-    wp->w_config = WIN_CONFIG_INIT;
+    merge_win_config(&wp->w_config, WIN_CONFIG_INIT);
     CLEAR_FIELD(wp->w_border_adj);
   }
 
diff --git a/src/nvim/winfloat.c b/src/nvim/winfloat.c
index 0a90f638f3..f7e9128599 100644
--- a/src/nvim/winfloat.c
+++ b/src/nvim/winfloat.c
@@ -203,13 +203,7 @@ void win_config_float(win_T *wp, WinConfig fconfig)
                                   wp->w_config.border_hl_ids,
                                   sizeof fconfig.border_hl_ids) != 0);
 
-  if (fconfig.title_chunks.items != wp->w_config.title_chunks.items) {
-    clear_virttext(&wp->w_config.title_chunks);
-  }
-  if (fconfig.footer_chunks.items != wp->w_config.footer_chunks.items) {
-    clear_virttext(&wp->w_config.footer_chunks);
-  }
-  wp->w_config = fconfig;
+  merge_win_config(&wp->w_config, fconfig);
 
   bool has_border = wp->w_floating && wp->w_config.border;
   for (int i = 0; i < 4; i++) {
diff --git a/test/functional/api/window_spec.lua b/test/functional/api/window_spec.lua
index 135b24fa5f..5ce93f9e04 100644
--- a/test/functional/api/window_spec.lua
+++ b/test/functional/api/window_spec.lua
@@ -1815,10 +1815,10 @@ describe('API/win', function()
         'title/footer must be string or array',
         pcall_err(api.nvim_open_win, 0, false, {
           relative = 'editor',
-          row = 5,
-          col = 5,
-          height = 5,
-          width = 5,
+          row = 10,
+          col = 10,
+          height = 10,
+          width = 10,
           border = 'single',
           title = { { 'TITLE' } },
           footer = 0,
@@ -1831,10 +1831,10 @@ describe('API/win', function()
         'title/footer must be string or array',
         pcall_err(api.nvim_open_win, 0, false, {
           relative = 'editor',
-          row = 5,
-          col = 5,
-          height = 5,
-          width = 5,
+          row = 10,
+          col = 10,
+          height = 10,
+          width = 10,
           border = 'single',
           title = 0,
           footer = { { 'FOOTER' } },
@@ -2840,10 +2840,10 @@ describe('API/win', function()
       before_each(function()
         win = api.nvim_open_win(0, false, {
           relative = 'editor',
-          row = 5,
-          col = 5,
-          height = 5,
-          width = 5,
+          row = 10,
+          col = 10,
+          height = 10,
+          width = 10,
           border = 'single',
           title = { { 'OLD_TITLE' } },
           footer = { { 'OLD_FOOTER' } },
diff --git a/test/functional/ui/float_spec.lua b/test/functional/ui/float_spec.lua
index 52b46d0ecb..b2ed5f5a5f 100644
--- a/test/functional/ui/float_spec.lua
+++ b/test/functional/ui/float_spec.lua
@@ -2562,6 +2562,37 @@ describe('float window', function()
       end
       eq({{"🦄", ""}, {"BB", {"B0", "B1", ""}}}, api.nvim_win_get_config(win).title)
       eq({{"🦄", ""}, {"BB", {"B0", "B1", ""}}}, api.nvim_win_get_config(win).footer)
+
+      -- making it a split should not leak memory
+      api.nvim_win_set_config(win, { vertical = true })
+      if multigrid then
+        screen:expect{grid=[[
+        ## grid 1
+          [4:--------------------]{5:│}[2:-------------------]|*5
+          {5:[No Name] [+]        }{4:[No Name]          }|
+          [3:----------------------------------------]|
+        ## grid 2
+          ^                   |
+          {0:~                  }|*4
+        ## grid 3
+                                                  |
+        ## grid 4
+           halloj!            |
+           BORDAA             |
+          {0:~                   }|*3
+        ]], win_viewport={
+          [2] = {win = 1000, topline = 0, botline = 2, curline = 0, curcol = 0, linecount = 1, sum_scroll_delta = 0};
+          [4] = {win = 1001, topline = 0, botline = 3, curline = 0, curcol = 0, linecount = 2, sum_scroll_delta = 0};
+        }}
+      else
+        screen:expect{grid=[[
+           halloj!            {5:│}^                   |
+           BORDAA             {5:│}{0:~                  }|
+          {0:~                   }{5:│}{0:~                  }|*3
+          {5:[No Name] [+]        }{4:[No Name]          }|
+                                                  |
+        ]]}
+      end
     end)
 
     it('terminates border on edge of viewport when window extends past viewport', function()