CMake Error at source_subfolder/CMakeLists.txt:532 (target_compile_features):
  target_compile_features The compiler feature "cxx_variable_templates" is
  not known to CXX compiler

  "GNU"

  version 4.9.4.


libtorrent/2.0.1: WARN: Build folder is dirty, removing it: /home/conan/w/cci_PR-3699/.conan/data/libtorrent/2.0.1/_/_/build/6cb5d8f5925c51edb7f7f13f8e2f8334c2f25c84
libtorrent/2.0.1: ERROR: Package '6cb5d8f5925c51edb7f7f13f8e2f8334c2f25c84' build failed
libtorrent/2.0.1: WARN: Build folder /home/conan/w/cci_PR-3699/.conan/data/libtorrent/2.0.1/_/_/build/6cb5d8f5925c51edb7f7f13f8e2f8334c2f25c84
ERROR: libtorrent/2.0.1: Error in build() method, line 136
	cmake = self._configure_cmake()
while calling '_configure_cmake', line 111
	self._cmake.configure()
	ConanException: Error 1 while executing cd '/home/conan/w/cci_PR-3699/.conan/data/libtorrent/2.0.1/_/_/build/6cb5d8f5925c51edb7f7f13f8e2f8334c2f25c84' && cmake -G "Unix Makefiles" -DCMAKE_BUILD_TYPE="Release" -DCONAN_IN_LOCAL_CACHE="ON" -DCONAN_COMPILER="gcc" -DCONAN_COMPILER_VERSION="4.9" -DCONAN_CXX_FLAGS="-m64" -DCONAN_SHARED_LINKER_FLAGS="-m64" -DCONAN_C_FLAGS="-m64" -DCONAN_LIBCXX="libstdc++" -DBUILD_SHARED_LIBS="ON" -DCMAKE_INSTALL_PREFIX="/home/conan/w/cci_PR-3699/.conan/data/libtorrent/2.0.1/_/_/package/6cb5d8f5925c51edb7f7f13f8e2f8334c2f25c84" -DCMAKE_INSTALL_BINDIR="bin" -DCMAKE_INSTALL_SBINDIR="bin" -DCMAKE_INSTALL_LIBEXECDIR="bin" -DCMAKE_INSTALL_LIBDIR="lib" -DCMAKE_INSTALL_INCLUDEDIR="include" -DCMAKE_INSTALL_OLDINCLUDEDIR="include" -DCMAKE_INSTALL_DATAROOTDIR="share" -DCMAKE_EXPORT_NO_PACKAGE_REGISTRY="ON" -DCONAN_EXPORTED="1" -DBoost_USE_STATIC_LIBS="True" -Ddeprecated-functions="True" -Ddht="True" -Dencryption="True" -Dexceptions="True" -Di2p="True" -Dlogging="True" -Dmutable-torrents="True" -Dbuild_tests="False" -Dbuild_examples="False" -Dbuild_tools="False" -Dpython-bindings="False" -Wno-dev '/home/conan/w/cci_PR-3699/.conan/data/libtorrent/2.0.1/_/_/build/6cb5d8f5925c51edb7f7f13f8e2f8334c2f25c84'