patch 8.2.2316: Vim9: cannot list a lambda function

Problem:    Vim9: cannot list a lambda function.
Solution:   Support the <lambda>9 notation, like :disassemble. (closes #7634)

src/testdir/test_vim9_func.vim

@@ -1802,6 +1802,16 @@ def Test_line_continuation_in_lambda()
   Line_continuation_in_lambda()->assert_equal(['D', 'C', 'B', 'A'])
 enddef
 
+def Test_list_lambda()
+  timer_start(1000, (_) => 0)
+  var body = execute(timer_info()[0].callback
+         ->string()
+         ->substitute("('", ' ', '')
+         ->substitute("')", '', '')
+         ->substitute('function\zs', ' ', ''))
+  assert_match('def <lambda>\d\+(_: any, ...): number\n1  return 0\n   enddef', body)
+enddef
+
 func Test_silent_echo()
   CheckScreendump
 

src/userfunc.c

@@ -3094,7 +3094,15 @@ define_function(exarg_T *eap, char_u *name_arg)
     }
     else
     {
-	name = trans_function_name(&p, &is_global, eap->skip,
+	if (STRNCMP(p, "<lambda>", 8) == 0)
+	{
+	    p += 8;
+	    (void)getdigits(&p);
+	    name = vim_strnsave(eap->arg, p - eap->arg);
+	    CLEAR_FIELD(fudi);
+	}
+	else
+	    name = trans_function_name(&p, &is_global, eap->skip,
 					   TFN_NO_AUTOLOAD, &fudi, NULL, NULL);
 	paren = (vim_strchr(p, '(') != NULL);
 	if (name == NULL && (fudi.fd_dict == NULL || !paren) && !eap->skip)

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2316,
 /**/
     2315,
 /**/