[Tarantool-patches] [PATCH] Fix wrong make_scoped_guard usage

[Aleksandr Lyapunov <alyapunov@tarantool.org>]

The common pitfall of using a lambda is wrong type of capture -
by value instead of by reference. The simple example is:
  struct sequence_def *new_def = NULL;
  auto def_guard = make_scoped_guard([=] { free(new_def); });
  // initialize new_def
The problem is that the lambda captures pointer by value, that
is NULL and will remain NULL in the lambda while new_def is
successfully initialized in function scope.

The patch fixes the problem above and a couple of similar mistakes.
---
 src/box/alter.cc | 4 ++--
 src/main.cc      | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/box/alter.cc b/src/box/alter.cc
index bb42548..3109fb4 100644
--- a/src/box/alter.cc
+++ b/src/box/alter.cc
@@ -3560,7 +3560,7 @@ on_replace_dd_func(struct trigger * /* trigger */, void *event)
 		 * definition to support upgrade script.
 		 */
 		struct func_def *old_def = NULL, *new_def = NULL;
-		auto guard = make_scoped_guard([=] {
+		auto guard = make_scoped_guard([&old_def, &new_def] {
 			free(old_def);
 			free(new_def);
 		});
@@ -4431,7 +4431,7 @@ on_replace_dd_sequence(struct trigger * /* trigger */, void *event)
 	struct tuple *new_tuple = stmt->new_tuple;
 
 	struct sequence_def *new_def = NULL;
-	auto def_guard = make_scoped_guard([=] { free(new_def); });
+	auto def_guard = make_scoped_guard([&new_def] { free(new_def); });
 
 	struct sequence *seq;
 	if (old_tuple == NULL && new_tuple != NULL) {		/* INSERT */
diff --git a/src/main.cc b/src/main.cc
index 2c96391..e622042 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -729,7 +729,7 @@ main(int argc, char **argv)
 	/* Lua interpeter options, e.g. -e and -l */
 	int optc = 0;
 	const char **optv = NULL;
-	auto guard = make_scoped_guard([=]{ if (optc) free(optv); });
+	auto guard = make_scoped_guard([&optc, &optv]{ if (optc) free(optv); });
 
 	static struct option longopts[] = {
 		{"help", no_argument, 0, 'h'},
-- 
2.7.4