vim-patch:8.2.1472: ":argdel" does not work like ":.argdel" as documented

Problem:    ":argdel" does not work like ":.argdel" as documented. (Alexey
            Demin)
Solution:   Make ":argdel" work like ":.argdel". (closes vim/vim#6727)
            Also fix giving the error "0 more files to edit".
7b22117c4e

src/nvim/ex_cmds2.c

@@ -1984,9 +1984,16 @@ void ex_argadd(exarg_T *eap)
 /// ":argdelete"
 void ex_argdelete(exarg_T *eap)
 {
-  if (eap->addr_count > 0) {
-    // ":1,4argdel": Delete all arguments in the range.
-    if (eap->line2 > ARGCOUNT) {
+  if (eap->addr_count > 0 || *eap->arg == NUL) {
+    // ":argdel" works like ":.argdel"
+    if (eap->addr_count == 0) {
+      if (curwin->w_arg_idx >= ARGCOUNT) {
+        EMSG(_("E610: No argument to delete"));
+        return;
+      }
+      eap->line1 = eap->line2 = curwin->w_arg_idx + 1;
+    } else if (eap->line2 > ARGCOUNT) {
+      // ":1,4argdel": Delete all arguments in the range.
       eap->line2 = ARGCOUNT;
     }
     linenr_T n = eap->line2 - eap->line1 + 1;
@@ -2016,8 +2023,6 @@ void ex_argdelete(exarg_T *eap)
           curwin->w_arg_idx = ARGCOUNT - 1;
       }
     }
-  } else if (*eap->arg == NUL) {
-    EMSG(_(e_argreq));
   } else {
     do_arglist(eap->arg, AL_DEL, 0);
   }

src/nvim/ex_docmd.c

@@ -4949,7 +4949,7 @@ check_more(
   int n = ARGCOUNT - curwin->w_arg_idx - 1;
 
   if (!forceit && only_one_window()
-      && ARGCOUNT > 1 && !arg_had_last && n >= 0 && quitmore == 0) {
+      && ARGCOUNT > 1 && !arg_had_last && n > 0 && quitmore == 0) {
     if (message) {
       if ((p_confirm || cmdmod.confirm) && curbuf->b_fname != NULL) {
         char_u buff[DIALOG_MSG_SIZE];

src/nvim/testdir/test_arglist.vim

@@ -397,9 +397,15 @@ func Test_argdelete()
   last
   argdelete %
   call assert_equal(['b'], argv())
-  call assert_fails('argdelete', 'E471:')
+  call assert_fails('argdelete', 'E610:')
   call assert_fails('1,100argdelete', 'E16:')
-  %argd
+
+  call Reset_arglist()
+  args a b c d
+  next
+  argdel
+  call Assert_argc(['a', 'c', 'd'])
+  %argdel
 endfunc
 
 func Test_argdelete_completion()

test/functional/legacy/arglist_spec.lua

@@ -42,9 +42,7 @@ describe('argument list commands', function()
   end)
 
   it('test that argadd() works', function()
-    -- Fails with “E474: Invalid argument”. Not sure whether it is how it is
-    -- supposed to behave.
-    -- command('%argdelete')
+    command('%argdelete')
     command('argadd a b c')
     eq(0, eval('argidx()'))
 
@@ -176,9 +174,14 @@ describe('argument list commands', function()
     command('last')
     command('argdelete %')
     eq({'b'}, eval('argv()'))
-    assert_fails('argdelete', 'E471:')
+    assert_fails('argdelete', 'E610:')
     assert_fails('1,100argdelete', 'E16:')
-    command('%argd')
+    reset_arglist()
+    command('args a b c d')
+    command('next')
+    command('argdel')
+    eq({'a', 'c', 'd'}, eval('argv()'))
+    command('%argdel')
   end)
 
   it('test for the :next, :prev, :first, :last, :rewind commands', function()