vim-patch:8.1.0800: may use a lot of memory when a function refers itself

Problem:    May use a lot of memory when a function creates a cyclic
            reference.
Solution:   After saving a funccal many times, invoke the garbage collector.
            (closes vim/vim#3835)
https://github.com/vim/vim/commit/4456ab527a6a5faae9287f3bd2e52cc18966cfb0

1 files changed, 11 insertions, 0 deletions

diff --git a/src/nvim/eval/userfunc.c b/src/nvim/eval/userfunc.c
index c55a29c67c..6e3c6c592a 100644
--- a/src/nvim/eval/userfunc.c
+++ b/src/nvim/eval/userfunc.c
@@ -592,6 +592,8 @@ static void cleanup_function_call(funccall_T *fc)
   if (!fc_referenced(fc)) {
     free_funccal(fc, false);
   } else {
+    static int made_copy = 0;
+
     // "fc" is still in use.  This can happen when returning "a:000",
     // assigning "l:" to a global variable or defining a closure.
     // Link "fc" in the list for garbage collection later.
@@ -607,6 +609,15 @@ static void cleanup_function_call(funccall_T *fc)
     TV_LIST_ITER(&fc->l_varlist, li, {
       tv_copy(TV_LIST_ITEM_TV(li), TV_LIST_ITEM_TV(li));
     });
+
+    if (++made_copy == 10000) {
+      // We have made a lot of copies.  This can happen when
+      // repetitively calling a function that creates a reference to
+      // itself somehow.  Call the garbage collector here to avoid using
+      // too much memory.
+      made_copy = 0;
+      (void)garbage_collect(false);
+    }
   }
 }