vim-patch:8.0.1505: debugger can't break on a condition

Problem:    Debugger can't break on a condition. (Charles Campbell)
Solution:   Add ":breakadd expr". (Christian Brabandt, closes vim/vim#859)
https://github.com/vim/vim/commit/c6f9f739d32084923c3031cbf6f581f8c8bf7fd2

Do not port "has_watchexpr()" to avoid dead code.
"has_watchexpr()" always returns 0 because "debug_expr" is always 0.

Restore "eval_expr()" as a wrapper to allocate "typval_T" for "eval0()".
Remove it in later patches.

Include "typval_compare()" changes from patch v8.1.0958,
partially ported in 8b60368c1b9e23f0695557da170d416d71f7e6a3.

Close https://github.com/neovim/neovim/pull/12373

N/A patches for version.c:

vim-patch:8.2.2720: GTK menu tooltip moves the cursor

Problem:    GTK menu tooltip moves the cursor.
Solution:   Position the cursor after displaying the tooltip.  Do not show the
            tooltip when editing the command line.
https://github.com/vim/vim/commit/01ac0a1f664c5b1ffd5c9ef196d4b47edf2fd494

1 files changed, 1 insertions, 24 deletions

diff --git a/src/nvim/eval/funcs.c b/src/nvim/eval/funcs.c
index fb72b9425e..0d288e2cc2 100644
--- a/src/nvim/eval/funcs.c
+++ b/src/nvim/eval/funcs.c
@@ -2051,7 +2051,6 @@ static void f_exepath(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 static void f_exists(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 {
   int n = false;
-  int len = 0;
 
   const char *p = tv_get_string(&argvars[0]);
   if (*p == '$') {  // Environment variable.
@@ -2082,29 +2081,7 @@ static void f_exists(typval_T *argvars, typval_T *rettv, FunPtr fptr)
       n = au_exists(p + 1);
     }
   } else {  // Internal variable.
-    typval_T tv;
-
-    // get_name_len() takes care of expanding curly braces
-    const char *name = p;
-    char *tofree;
-    len = get_name_len((const char **)&p, &tofree, true, false);
-    if (len > 0) {
-      if (tofree != NULL) {
-        name = tofree;
-      }
-      n = (get_var_tv(name, len, &tv, NULL, false, true) == OK);
-      if (n) {
-        // Handle d.key, l[idx], f(expr).
-        n = (handle_subscript(&p, &tv, true, false) == OK);
-        if (n) {
-          tv_clear(&tv);
-        }
-      }
-    }
-    if (*p != NUL)
-      n = FALSE;
-
-    xfree(tofree);
+    n = var_exists(p);
   }
 
   rettv->vval.v_number = n;