vim-patch:8.2.3545: setcellwidths() may make 'listchars' or 'fillchars' invalid

Problem:    setcellwidths() may make 'listchars' or 'fillchars' invalid.
Solution:   Check the value and give an error. (closes vim/vim#9024)
https://github.com/vim/vim/commit/94358a1e6e640ca5ebeb295efdddd4e92b700673

Cherry-pick f_setcellwidths() change from patch 9.0.0036.
Cherry-pick 'ambiwidth' docs update from runtime update 079ba76ae7a7.

1 files changed, 32 insertions, 1 deletions

diff --git a/src/nvim/mbyte.c b/src/nvim/mbyte.c
index e19c356343..5de7231a0a 100644
--- a/src/nvim/mbyte.c
+++ b/src/nvim/mbyte.c
@@ -2838,7 +2838,38 @@ void f_setcellwidths(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   }
 
   xfree(ptrs);
-  xfree(cw_table);
+
+  cw_interval_T *const cw_table_save = cw_table;
+  const size_t cw_table_size_save = cw_table_size;
   cw_table = table;
   cw_table_size = (size_t)tv_list_len(l);
+
+  // Check that the new value does not conflict with 'fillchars' or
+  // 'listchars'.
+  char *error = NULL;
+  if (set_chars_option(curwin, &p_fcs, false) != NULL) {
+    error = e_conflicts_with_value_of_fillchars;
+  } else if (set_chars_option(curwin, &p_lcs, false) != NULL) {
+    error = e_conflicts_with_value_of_listchars;
+  } else {
+    FOR_ALL_TAB_WINDOWS(tp, wp) {
+      if (set_chars_option(wp, &wp->w_p_lcs, false) != NULL) {
+        error = e_conflicts_with_value_of_listchars;
+        break;
+      }
+      if (set_chars_option(wp, &wp->w_p_fcs, false) != NULL) {
+        error = e_conflicts_with_value_of_fillchars;
+        break;
+      }
+    }
+  }
+  if (error != NULL) {
+    emsg(_(error));
+    cw_table = cw_table_save;
+    cw_table_size = cw_table_size_save;
+    xfree(table);
+    return;
+  }
+
+  xfree(cw_table_save);
 }