patch 8.2.4615: mapping with escaped bar does not work in :def function

Problem:    Mapping with escaped bar does not work in :def function. (Sergey
            Vlasov)
Solution:   Do not remove the backslash. (closes #10002)

src/ex_docmd.c

@@ -2275,7 +2275,7 @@ do_one_cmd(
      */
     if ((ea.argt & EX_TRLBAR) && !ea.usefilter)
     {
-	separate_nextcmd(&ea);
+	separate_nextcmd(&ea, FALSE);
     }
     else if (ea.cmdidx == CMD_bang
 	    || ea.cmdidx == CMD_terminal
@@ -5081,9 +5081,10 @@ repl_cmdline(
 
 /*
  * Check for '|' to separate commands and '"' to start comments.
+ * If "keep_backslash" is TRUE do not remove any backslash.
  */
     void
-separate_nextcmd(exarg_T *eap)
+separate_nextcmd(exarg_T *eap, int keep_backslash)
 {
     char_u	*p;
 
@@ -5097,7 +5098,7 @@ separate_nextcmd(exarg_T *eap)
     {
 	if (*p == Ctrl_V)
 	{
-	    if (eap->argt & (EX_CTRLV | EX_XFILE))
+	    if ((eap->argt & (EX_CTRLV | EX_XFILE)) || keep_backslash)
 		++p;		// skip CTRL-V and next char
 	    else
 				// remove CTRL-V and skip next char
@@ -5144,8 +5145,11 @@ separate_nextcmd(exarg_T *eap)
 	    if ((vim_strchr(p_cpo, CPO_BAR) == NULL
 			      || !(eap->argt & EX_CTRLV)) && *(p - 1) == '\\')
 	    {
-		STRMOVE(p - 1, p);	// remove the '\'
-		--p;
+		if (!keep_backslash)
+		{
+		    STRMOVE(p - 1, p);	// remove the '\'
+		    --p;
+		}
 	    }
 	    else
 	    {

src/proto/ex_docmd.pro

@@ -26,7 +26,7 @@ long excmd_get_argt(cmdidx_T idx);
 char_u *skip_range(char_u *cmd_start, int skip_star, int *ctx);
 void ex_ni(exarg_T *eap);
 int expand_filename(exarg_T *eap, char_u **cmdlinep, char **errormsgp);
-void separate_nextcmd(exarg_T *eap);
+void separate_nextcmd(exarg_T *eap, int keep_backslash);
 char_u *skip_cmd_arg(char_u *p, int rembs);
 int get_bad_opt(char_u *p, exarg_T *eap);
 int ends_excmd(int c);

src/syntax.c

@@ -4764,7 +4764,7 @@ syn_cmd_include(exarg_T *eap, int syncing UNUSED)
      * filename to include.
      */
     eap->argt |= (EX_XFILE | EX_NOSPC);
-    separate_nextcmd(eap);
+    separate_nextcmd(eap, FALSE);
     if (*eap->arg == '<' || *eap->arg == '$' || mch_isFullName(eap->arg))
     {
 	// For an absolute path, "$VIM/..." or "<sfile>.." we ":source" the

src/testdir/test_vim9_cmd.vim

@@ -1178,8 +1178,19 @@ def Test_map_command()
       nnoremap <F3> :echo 'hit F3 #'<CR>
       assert_equal(":echo 'hit F3 #'<CR>", maparg("<F3>", "n"))
   END
-  v9.CheckDefSuccess(lines)
-  v9.CheckScriptSuccess(['vim9script'] + lines)
+  v9.CheckDefAndScriptSuccess(lines)
+
+  # backslash before bar is not removed
+  lines =<< trim END
+      vim9script
+
+      def Init()
+        noremap <buffer> <F5> <ScriptCmd>MyFunc('a') \| MyFunc('b')<CR>
+      enddef
+      Init()
+      unmap <buffer> <F5>
+  END
+  v9.CheckScriptSuccess(lines)
 enddef
 
 def Test_normal_command()

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    4615,
 /**/
     4614,
 /**/

src/vim9cmds.c

@@ -1848,7 +1848,7 @@ compile_exec(char_u *line_arg, exarg_T *eap, cctx_T *cctx)
 	if ((argt & EX_TRLBAR) && !usefilter)
 	{
 	    eap->argt = argt;
-	    separate_nextcmd(eap);
+	    separate_nextcmd(eap, TRUE);
 	    if (eap->nextcmd != NULL)
 		nextcmd = eap->nextcmd;
 	}