Warning: memcpy forming offset [28, 128] is out of the bounds [0, 28] of object 'endpoint'

[pps83]

I have a warning that I get when compiling code that uses boost::beast. This happens only on msys2 when compiling with g++ (my version is 15.1.0). This warning doesn't really make much sense as it doesn't even show what code specifically leads to it:

mtlro@MAIN-NOTE MINGW64 /d/work-pps/backtest-engine/vs
$ nice -20 cmake --build $BUILD
[3/4] Building CXX object CMakeFiles/test.dir/src/test/WebSocketTest.cpp.obj
In file included from D:/work-pps/boost_1_89_0/boost/asio/ip/basic_resolver.hpp:32,
                 from D:/work-pps/boost_1_89_0/boost/asio/ip/tcp.hpp:25,
                 from D:/work-pps/boost_1_89_0/boost/beast/core/tcp_stream.hpp:17,
                 from D:/work-pps/boost_1_89_0/boost/beast/core.hpp:49,
                 from D:/work-pps/boost_1_89_0/boost/beast.hpp:15,
                 from D:/work-pps/backtest-engine/src/test/WebSocketTest.cpp:1:
D:/work-pps/boost_1_89_0/boost/asio/ip/basic_resolver_results.hpp: In static member function 'static boost::asio::ip::basic_resolver_results<InternetProtocol> boost::asio::ip::basic_resolver_results<InternetProtocol>::create(boost::asio::detail::addrinfo_type*, const std::string&, const std::string&) [with InternetProtocol = boost::asio::ip::tcp]':
D:/work-pps/boost_1_89_0/boost/asio/ip/basic_resolver_results.hpp:139:15: warning: 'void* memcpy(void*, const void*, size_t)' forming offset [28, 128] is out of the bounds [0, 28] of object 'endpoint' with type 'boost::asio::ip::tcp::endpoint' {aka 'boost::asio::ip::basic_endpoint<boost::asio::ip::tcp>'} [-Warray-bounds=]
  139 |         memcpy(endpoint.data(), address_info->ai_addr,
      |         ~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  140 |             address_info->ai_addrlen);
      |             ~~~~~~~~~~~~~~~~~~~~~~~~~
D:/work-pps/boost_1_89_0/boost/asio/ip/basic_resolver_results.hpp:137:45: note: 'endpoint' declared here
  137 |         typename InternetProtocol::endpoint endpoint;
      |                                             ^~~~~~~~

Here's the trimmed code that produces this warning:

#include <boost/beast.hpp>

namespace net = boost::asio;
namespace ssl = net::ssl;
namespace beast = boost::beast;
namespace http = beast::http;
namespace websocket = beast::websocket;

void test()
{
    using tcp = net::ip::tcp;
    net::io_context ioc_ws;
    tcp::resolver resolver_ws{ioc_ws};
    std::unique_ptr<websocket::stream<tcp::socket>> ws;

    ws = std::make_unique<websocket::stream<tcp::socket>>(ioc_ws);
    auto results = resolver_ws.resolve("127.0.0.1", "80");
    net::connect(ws->next_layer(), results.begin(), results.end());
    ws->handshake("127.0.0.1", "/ws");
}

I use boost 1.89. I had the same warning with older versions as well.

[vinniefalco]

What happens when you remove beast entirely and instead of using a websocket::stream use an asio::ip::tcp::socket ?

[pps83]

I tried to change to this:

#include <boost/asio.hpp>

namespace net = boost::asio;

void test()
{
    using tcp = net::ip::tcp;
    net::io_context ioc_ws;
    tcp::resolver resolver_ws{ioc_ws};
    std::unique_ptr<boost::asio::ip::tcp::socket> ws;

    ws = std::make_unique<boost::asio::ip::tcp::socket>(ioc_ws);
    auto results = resolver_ws.resolve("127.0.0.1", "80");
    net::connect(ws->lowest_layer(), results.begin(), results.end());
}

got the same error

[ashtum]

This looks like a Asio issue. Could you please open an issue here: https://github.com/chriskohlhoff/asio/issues?
What compiler flags are you using? It would help if you could come up with a reproducible example on https://godbolt.org/.

[sehe]

To me it looks like a MINGW issue (false positive diagnostic) - but compiler explorer doesn't allow us to repro https://godbolt.org/z/8xbKdshYW

[pps83]

This looks like a Asio issue. Could you please open an issue here: https://github.com/chriskohlhoff/asio/issues? What compiler flags are you using? It would help if you could come up with a reproducible example on https://godbolt.org/.

Not sure if it's false diag, but it's too specific with these offsets. Looks very strange imo.

What compiler flags are you using? It would help if you could come up with a reproducible example on https://godbolt.org/.

Godbolt has issues using libs with non-linux targets afaik (cannot use boost basically with g++ on windows). I use regular cmake build, here is trimmed cmd that results in the warning:

D:\msys64\mingw64\bin\c++.exe -ID:/work-pps/boost_1_89_0 -O3 -DNDEBUG -std=c++23 -march=skylake -Wformat -Wall -Werror=format -x c++ -o CMakeFiles/test.dir/src/test/WebSocketTest.cpp.obj -c D:/work-pps/backtest-engine/src/test/WebSocketTest.cpp