use size_t instead of int for overrun counter

include/spdlog/details/circular_q.h

@@ -54,7 +54,7 @@ public:
         return ((tail_ + 1) % max_items_) == head_;
     }
 
-    int overrun_counter() const
+    size_t overrun_counter() const
     {
       return overrun_counter_;
     }
@@ -66,7 +66,7 @@ private:
 
     std::vector<T> v_;
 
-    int overrun_counter_ = 0;
+    size_t overrun_counter_ = 0;
 };
 } // namespace details
 } // namespace spdlog

include/spdlog/details/mpmc_blocking_q.h

@@ -30,7 +30,7 @@ public:
     {
     }
 
-    int overrun_counter() const
+    size_t overrun_counter() const
     {
       return q_.overrun_counter();
     }

include/spdlog/details/thread_pool.h

@@ -157,7 +157,7 @@ public:
         post_async_msg_(async_msg(std::move(worker_ptr), async_msg_type::flush), overflow_policy);
     }
 
-    int overrun_counter() const
+    size_t overrun_counter() const
     {
       return q_.overrun_counter();
     }

tests/test_async.cpp

@@ -7,7 +7,7 @@ TEST_CASE("basic async test ", "[async]")
 {
     using namespace spdlog;
     auto test_sink = std::make_shared<sinks::test_sink_mt>();
-    int overrun_counter = 0;
+    size_t overrun_counter = 0;
     size_t queue_size = 128;
     size_t messages = 256;
     {