wget http://mirrors.ustc.edu.cn/gnu/gcc/gcc-5.2.0/gcc-5.2.0.tar.gz
tar xf gcc-5.2.0.tar.gz
cd gcc-5.2.0
./contrib/download_prerequisites
mkdir build
cd build
../configure --enable-bootstrap --enable-languages=c,c++ --disable-multilib --prefix=/opt/cxx-5.2.0
make -j2
make install
原文：http://my.oschina.net/u/1445655/blog/479790