vim-patch:8.2.1007: completion doesn't work after ":r ++arg !"

Problem:    Completion doesn't work after ":r ++arg !".
Solution:   Skip over "++arg". (Christian Brabandt, closes vim/vim#6275,
            closes vim/vim#6258)
https://github.com/vim/vim/commit/c8cb883015619cfe6db931ac2d6e15b0be5c56ed

2 files changed, 23 insertions, 0 deletions

diff --git a/src/nvim/ex_docmd.c b/src/nvim/ex_docmd.c
index 601f4aab38..dea0d21ad2 100644
--- a/src/nvim/ex_docmd.c
+++ b/src/nvim/ex_docmd.c
@@ -3020,6 +3020,15 @@ const char * set_one_cmd_context(
     arg = (const char *)skipwhite((const char_u *)arg);
   }
 
+  // Skip over ++argopt argument
+  if ((ea.argt & ARGOPT) && *arg != NUL && strncmp(arg, "++", 2) == 0) {
+    p = arg;
+    while (*p && !ascii_isspace(*p)) {
+      MB_PTR_ADV(p);
+    }
+    arg = (const char *)skipwhite((const char_u *)p);
+  }
+
   /*
    * Check for '|' to separate commands and '"' to start comments.
    * Don't do this for ":read !cmd" and ":write !cmd".
diff --git a/src/nvim/testdir/test_cmdline.vim b/src/nvim/testdir/test_cmdline.vim
index 5b23525ab5..09f02593a3 100644
--- a/src/nvim/testdir/test_cmdline.vim
+++ b/src/nvim/testdir/test_cmdline.vim
@@ -955,5 +955,19 @@ func Test_zero_line_search()
   q!
 endfunc
 
+func Test_read_shellcmd()
+  CheckUnix
+  if executable('ls')
+    " There should be ls in the $PATH
+    call feedkeys(":r! l\<c-a>\<c-b>\"\<cr>", 'tx')
+    call assert_match('^"r! .*\<ls\>', @:)
+  endif
+
+  if executable('rm')
+    call feedkeys(":r! ++enc=utf-8 r\<c-a>\<c-b>\"\<cr>", 'tx')
+    call assert_notmatch('^"r!.*\<runtest.vim\>', @:)
+    call assert_match('^"r!.*\<rm\>', @:)
+  endif
+endfunc
 
 " vim: shiftwidth=2 sts=2 expandtab	" vim: shiftwidth=2 sts=2 expandtab