fix(statuscolumn): don't update clicks if current width is 0 (#24459)

src/nvim/drawline.c

@@ -686,7 +686,7 @@ static void get_statuscol_str(win_T *wp, linenr_T lnum, int virtnum, statuscol_T
   int width = build_statuscol_str(wp, lnum, relnum, stcp);
   // Force a redraw in case of error or when truncated
   if (*wp->w_p_stc == NUL || (stcp->truncate > 0 && wp->w_nrwidth < MAX_NUMBERWIDTH)) {
-    if (stcp->truncate) {  // Avoid truncating 'statuscolumn'
+    if (stcp->truncate > 0) {  // Avoid truncating 'statuscolumn'
       wp->w_nrwidth = MIN(MAX_NUMBERWIDTH, wp->w_nrwidth + stcp->truncate);
       wp->w_nrwidth_width = wp->w_nrwidth;
     } else {  // 'statuscolumn' reset due to error

src/nvim/statusline.c

@@ -890,7 +890,9 @@ void draw_tabline(void)
 /// @return  The width of the built status column string for line "lnum"
 int build_statuscol_str(win_T *wp, linenr_T lnum, long relnum, statuscol_T *stcp)
 {
-  bool fillclick = relnum >= 0 && lnum == wp->w_topline;
+  // Only update click definitions once per window per redraw.
+  // Don't update when current width is 0, since it will be redrawn again if not empty.
+  const bool fillclick = relnum >= 0 && stcp->width > 0 && lnum == wp->w_topline;
 
   if (relnum >= 0) {
     set_vim_var_nr(VV_LNUM, lnum);
@@ -903,7 +905,6 @@ int build_statuscol_str(win_T *wp, linenr_T lnum, long relnum, statuscol_T *stcp
                                stcp->width, &stcp->hlrec, fillclick ? &clickrec : NULL, stcp);
   xfree(stc);
 
-  // Only update click definitions once per window per redraw
   if (fillclick) {
     stl_clear_click_defs(wp->w_statuscol_click_defs, wp->w_statuscol_click_defs_size);
     wp->w_statuscol_click_defs = stl_alloc_click_defs(wp->w_statuscol_click_defs, stcp->width,
@@ -1973,8 +1974,8 @@ int build_stl_str_hl(win_T *wp, char *out, size_t outlen, char *fmt, char *opt_n
 
   int width = vim_strsize(out);
   // Return truncated width for 'statuscolumn'
-  if (stcp != NULL && width > maxwidth) {
+  if (stcp != NULL && width > stcp->width) {
-    stcp->truncate = width - maxwidth;
+    stcp->truncate = width - stcp->width;
   }
   if (maxwidth > 0 && width > maxwidth) {
     // Result is too long, must truncate somewhere.

test/functional/ui/statuscolumn_spec.lua

@@ -9,6 +9,7 @@ local exec_lua = helpers.exec_lua
 local feed = helpers.feed
 local meths = helpers.meths
 local pcall_err = helpers.pcall_err
+local assert_alive = helpers.assert_alive
 
 local mousemodels = { "extend", "popup", "popup_setpos" }
 
@@ -577,8 +578,8 @@ describe('statuscolumn', function()
     end)
   end
 
-  it('click labels do not leak memory', function()
+  it('click labels do not leak memory #21878', function()
-    command([[
+    exec([[
       set laststatus=2
       setlocal statuscolumn=%0@MyClickFunc@abcd%T
       4vsplit
@@ -590,6 +591,18 @@ describe('statuscolumn', function()
     ]])
   end)
 
+  it('click labels do not crash when initial width is 0 #24428', function()
+    exec([[
+      set nonumber
+      bwipe!
+      setlocal statuscolumn=abcd
+      redraw
+      setlocal statuscolumn=%0@MyClickFunc@abcd%T
+      redraw
+    ]])
+    assert_alive()
+  end)
+
   it('works with foldcolumn', function()
     -- Fits maximum multibyte foldcolumn #21759
     command([[set stc=%C%=%l\  fdc=9 fillchars=foldsep:𒀀]])