vim-patch:8.2.3888: the argument list may contain duplicates (#19795)

Problem:    The argument list may contain duplicates.
Solution:   Add the :argdedeupe command. (Nir Lichtman, closes vim/vim#6235)
https://github.com/vim/vim/commit/73a024209cbfbd5b39a2e974084d807c6131e2ed

Use latest index.txt :argdedupe doc from Vim.

5 files changed, 68 insertions, 2 deletions

diff --git a/runtime/doc/editing.txt b/runtime/doc/editing.txt
index c19d9f482b..dcb0bf8a2e 100644
--- a/runtime/doc/editing.txt
+++ b/runtime/doc/editing.txt
@@ -613,12 +613,19 @@ list of the current window.
 			And after the last one:
 				:+2argadd y	a b c x y
 			There is no check for duplicates, it is possible to
-			add a file to the argument list twice.
-			The currently edited file is not changed.
+			add a file to the argument list twice.  You can use
+			|:argdedupe| to fix it afterwards: >
+				:argadd *.txt | argdedupe
+<			The currently edited file is not changed.
 			Note: you can also use this method: >
 				:args ## x
 <			This will add the "x" item and sort the new list.
 
+:argded[upe]					*:argded* *:argdedupe*
+			Remove duplicate filenames from the argument list.
+			If your current file is a duplicate, your current file
+			will change to the original file index.
+
 :argd[elete] {pattern} ..		*:argd* *:argdelete* *E480* *E610*
 			Delete files from the argument list that match the
 			{pattern}s.  {pattern} is used like a file pattern,
diff --git a/runtime/doc/index.txt b/runtime/doc/index.txt
index 7d8a89887a..7f3ef20762 100644
--- a/runtime/doc/index.txt
+++ b/runtime/doc/index.txt
@@ -1143,6 +1143,7 @@ tag		command		action ~
 				be remapped
 |:args|		:ar[gs]		print the argument list
 |:argadd|	:arga[dd]	add items to the argument list
+|:argdedupe|	:argded[upe]	remove duplicates from the argument list
 |:argdelete|	:argd[elete]	delete items from the argument list
 |:argedit|	:arge[dit]	add item to the argument list and edit it
 |:argdo|	:argdo		do a command on all items in the argument list
diff --git a/src/nvim/arglist.c b/src/nvim/arglist.c
index d19f6ed623..7d8917cc73 100644
--- a/src/nvim/arglist.c
+++ b/src/nvim/arglist.c
@@ -620,6 +620,29 @@ void ex_next(exarg_T *eap)
   }
 }
 
+/// ":argdedupe"
+void ex_argdedupe(exarg_T *eap FUNC_ATTR_UNUSED)
+{
+  for (int i = 0; i < ARGCOUNT; i++) {
+    for (int j = i + 1; j < ARGCOUNT; j++) {
+      if (FNAMECMP(ARGLIST[i].ae_fname, ARGLIST[j].ae_fname) == 0) {
+        xfree(ARGLIST[j].ae_fname);
+        memmove(ARGLIST + j, ARGLIST + j + 1,
+                (size_t)(ARGCOUNT - j - 1) * sizeof(aentry_T));
+        ARGCOUNT--;
+
+        if (curwin->w_arg_idx == j) {
+          curwin->w_arg_idx = i;
+        } else if (curwin->w_arg_idx > j) {
+          curwin->w_arg_idx--;
+        }
+
+        j--;
+      }
+    }
+  }
+}
+
 /// ":argedit"
 void ex_argedit(exarg_T *eap)
 {
diff --git a/src/nvim/ex_cmds.lua b/src/nvim/ex_cmds.lua
index a5ba5e0b30..37f12a7600 100644
--- a/src/nvim/ex_cmds.lua
+++ b/src/nvim/ex_cmds.lua
@@ -107,6 +107,12 @@ module.cmds = {
     func='ex_listdo',
   },
   {
+    command='argdedupe',
+    flags=TRLBAR,
+    addr_type='ADDR_NONE',
+    func='ex_argdedupe',
+  },
+  {
     command='argedit',
     flags=bit.bor(BANG, NEEDARG, RANGE, ZEROR, FILES, CMDARG, ARGOPT, TRLBAR),
     addr_type='ADDR_ARGUMENTS',
diff --git a/src/nvim/testdir/test_arglist.vim b/src/nvim/testdir/test_arglist.vim
index 0a72e38755..521c3fcd57 100644
--- a/src/nvim/testdir/test_arglist.vim
+++ b/src/nvim/testdir/test_arglist.vim
@@ -412,6 +412,35 @@ func Test_argedit()
   bw! x
 endfunc
 
+" Test for the :argdedupe command
+func Test_argdedupe()
+  call Reset_arglist()
+  argdedupe
+  call assert_equal([], argv())
+  args a a a aa b b a b aa
+  argdedupe
+  call assert_equal(['a', 'aa', 'b'], argv())
+  args a b c
+  argdedupe
+  call assert_equal(['a', 'b', 'c'], argv())
+  args a
+  argdedupe
+  call assert_equal(['a'], argv())
+  args a A b B
+  argdedupe
+  if has('fname_case')
+    call assert_equal(['a', 'A', 'b', 'B'], argv())
+  else
+    call assert_equal(['a', 'b'], argv())
+  endif
+  args a b a c a b
+  last
+  argdedupe
+  next
+  call assert_equal('c', expand('%:t'))
+  %argd
+endfunc
+
 " Test for the :argdelete command
 func Test_argdelete()
   call Reset_arglist()