vcpkg install on linux skip detect poll API #9921

I did this

After running vcpkg install curl , running grep HAVE_POLL_FINE <VCPKG_DIR>/buildtrees/curl/x64-linux-rel/lib/curl_config.h, it shows

/* #undef HAVE_POLL_FINE */

Without poll API, curl multi-api cannot handle more than 1024 concurrent connections with select API.

I expected the following

curl build with poll api supported: HAVE_POLL_FINE should be defined in curl_config.h

curl/libcurl version

7.84.0

operating system

Linux phillip-dev 5.15.0-52-generic #58-Ubuntu SMP Thu Oct 13 08:03:55 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux

Root Cause

CMake script skip detecting poll API if CMAKE_TOOLCHAIN_FILE defined(My guess: skip detecting POLL API if cross-compile). CMAKE_TOOLCHAIN_FILE is always defined in vcpkg:https://vcpkg.io/en/docs/maintainers/vcpkg_cmake_configure.html#implicit-options