https://github.com/paullouisageneau/boost-asio-gnutls/commit/895105972e5a9318d572b147c1872f64d23e2a8e
https://bugs.gentoo.org/820836
https://github.com/arvidn/libtorrent/pull/6546

From 895105972e5a9318d572b147c1872f64d23e2a8e Mon Sep 17 00:00:00 2001
From: Shantanu Singh <shsi@microsoft.com>
Date: Fri, 18 Sep 2020 14:01:39 -0700
Subject: [PATCH] Use fully qualified std::placeholders to prevent conflicts
 with boost::placeholders

--- a/deps/asio-gnutls/include/boost/asio/gnutls/stream.hpp
+++ b/deps/asio-gnutls/include/boost/asio/gnutls/stream.hpp
@@ -244,8 +244,7 @@ template <typename NextLayer> class stream : public stream_base
             return;
         }
 
-        using namespace std::placeholders;
-        m_impl->read_handler = std::bind(callable, _1, _2);
+        m_impl->read_handler = std::bind(callable, std::placeholders::_1, std::placeholders::_2);
         m_impl->bytes_read = 0;
         m_impl->async_schedule();
         return callable.get_completion_result();
@@ -293,8 +292,7 @@ template <typename NextLayer> class stream : public stream_base
             return;
         }
 
-        using namespace std::placeholders;
-        m_impl->write_handler = std::bind(callable, _1, _2);
+        m_impl->write_handler = std::bind(callable, std::placeholders::_1, std::placeholders::_2);
         m_impl->bytes_written = 0;
         m_impl->async_schedule();
         return callable.get_completion_result();
@@ -568,8 +566,6 @@ template <typename NextLayer> class stream : public stream_base
 
         void async_schedule()
         {
-            using namespace std::placeholders;
-
             if (!parent) return;
             auto& next_layer = parent->m_next_layer;
 
@@ -581,14 +577,14 @@ template <typename NextLayer> class stream : public stream_base
                 else
                     next_layer.async_wait(
                         next_layer_type::wait_read,
-                        std::bind(&impl::handle_read, this->shared_from_this(), _1));
+                        std::bind(&impl::handle_read, this->shared_from_this(), std::placeholders::_1));
             }
 
             // Start a write operation if GnuTLS wants one
             if (want_write() && !std::exchange(is_writing, true))
             {
                 next_layer.async_wait(next_layer_type::wait_write,
-                        std::bind(&impl::handle_write, this->shared_from_this(), _1));
+                        std::bind(&impl::handle_write, this->shared_from_this(), std::placeholders::_1));
             }
         }