vim-patch:8.1.1579: dict and list could be GC'ed while displaying error

Problem:    Dict and list could be GC'ed while displaying error in a timer.
            (Yasuhiro Matsumoto)
Solution:   Block garbage collection when executing a timer.  Add
            test_garbagecollect_soon(). Add "no_wait_return" to
            test_override(). (closes vim/vim#4571)
adc6714aac

src/nvim/eval.c

@@ -5920,7 +5920,7 @@ static int dict_get_tv(char_u **arg, typval_T *rettv, int evaluate)
   if (**arg != '}') {
     EMSG2(_("E723: Missing end of Dictionary '}': %s"), *arg);
 failret:
-    if (evaluate) {
+    if (d != NULL) {
       tv_dict_free(d);
     }
     return FAIL;

src/nvim/eval/typval.c

@@ -1306,7 +1306,7 @@ void tv_dict_item_remove(dict_T *const dict, dictitem_T *const item)
 dict_T *tv_dict_alloc(void)
   FUNC_ATTR_NONNULL_RET FUNC_ATTR_WARN_UNUSED_RESULT
 {
-  dict_T *const d = xmalloc(sizeof(dict_T));
+  dict_T *const d = xcalloc(1, sizeof(dict_T));
 
   // Add the dict to the list of dicts for garbage collection.
   if (gc_first_dict != NULL) {

src/nvim/getchar.c

@@ -1518,7 +1518,7 @@ int vgetc(void)
    * collection in the first next vgetc().  It's disabled after that to
    * avoid internally used Lists and Dicts to be freed.
    */
-  may_garbage_collect = FALSE;
+  may_garbage_collect = false;
 
   return c;
 }

src/nvim/globals.h

@@ -325,7 +325,7 @@ EXTERN except_T *caught_stack INIT(= NULL);
 /// we do garbage collection before waiting for a char at the toplevel.
 /// "garbage_collect_at_exit" indicates garbagecollect(1) was called.
 ///
-EXTERN int may_garbage_collect INIT(= false);
+EXTERN bool may_garbage_collect INIT(= false);
 EXTERN int want_garbage_collect INIT(= false);
 EXTERN int garbage_collect_at_exit INIT(= false);
 

src/nvim/testdir/test_timers.vim

@@ -313,4 +313,30 @@ func Test_restore_count()
   call delete('Xtrctext')
 endfunc
 
+" Test that the garbage collector isn't triggered if a timer callback invokes
+" vgetc().
+func Test_nocatch_garbage_collect()
+  " skipped: Nvim does not support test_garbagecollect_soon(), test_override()
+  return
+  " 'uptimetime. must be bigger than the timer timeout
+  set ut=200
+  call test_garbagecollect_soon()
+  call test_override('no_wait_return', 0)
+  func CauseAnError(id)
+    " This will show an error and wait for Enter.
+    let a = {'foo', 'bar'}
+  endfunc
+  func FeedChar(id)
+    call feedkeys('x', 't')
+  endfunc
+  call timer_start(300, 'FeedChar')
+  call timer_start(100, 'CauseAnError')
+  let x = getchar()
+
+  set ut&
+  call test_override('no_wait_return', 1)
+  delfunc CauseAnError
+  delfunc FeedChar
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab

test/unit/eval/helpers.lua

@@ -406,7 +406,7 @@ end
 local alloc_logging_helpers = {
   list = function(l) return {func='calloc', args={1, ffi.sizeof('list_T')}, ret=void(l)} end,
   li = function(li) return {func='malloc', args={ffi.sizeof('listitem_T')}, ret=void(li)} end,
-  dict = function(d) return {func='malloc', args={ffi.sizeof('dict_T')}, ret=void(d)} end,
+  dict = function(d) return {func='calloc', args={1, ffi.sizeof('dict_T')}, ret=void(d)} end,
   di = function(di, size)
     size = alloc_len(size, function() return di.di_key end)
     return {func='malloc', args={ffi.offsetof('dictitem_T', 'di_key') + size + 1}, ret=void(di)}