patch 9.0.0949: crash when unletting a variable while listing variablesv9.0.0949

Problem:    Crash when unletting a variable while listing variables.
Solution:   Disallow changing a hashtable while going over the entries.
            (closes #11435)

1 files changed, 22 insertions, 0 deletions

diff --git a/src/testdir/test_autocmd.vim b/src/testdir/test_autocmd.vim
index aa204c4f37..a0d83ecf35 100644
--- a/src/testdir/test_autocmd.vim
+++ b/src/testdir/test_autocmd.vim
@@ -2326,6 +2326,28 @@ func Test_autocmd_user_clear_group()
   call StopVimInTerminal(buf)
 endfunc
 
+func Test_autocmd_CmdlineLeave_unlet()
+  CheckRunVimInTerminal
+
+  let lines =<< trim END
+      for i in range(1, 999)
+        exe 'let g:var' .. i '=' i
+      endfor
+      au CmdlineLeave : call timer_start(0, {-> execute('unlet g:var990')})
+  END
+  call writefile(lines, 'XleaveUnlet', 'D')
+  let buf = RunVimInTerminal('-S XleaveUnlet', {'rows': 10})
+
+  " this was using freed memory
+  call term_sendkeys(buf, ":let g:\<CR>")
+  call TermWait(buf, 50)
+  call term_sendkeys(buf, "G")
+  call TermWait(buf, 50)
+  call term_sendkeys(buf, "\<CR>")  " for the hit-enter prompt
+
+  call StopVimInTerminal(buf)
+endfunc
+
 function s:Before_test_dirchanged()
   augroup test_dirchanged
     autocmd!