安装GMP

cd gmp*;mkdir build && cd build  
../configure --prefix=/usr/local/gcc4.9.2 --enable-cxx
make;make install

安装MPFR

cd ../../mpfr*;mkdir build && cd build  
../configure --prefix=/usr/local/gcc4.9.2 --with-gmp=/usr/local/gcc4.9.2
make;make install

安装MPC

cd ../../mpc*;mkdir build && cd build  
../configure --prefix=/usr/local/gcc4.9.2 --with-gmp=/usr/local/gcc4.9.2 --with-mpfr=/usr/local/gcc4.9.2  
make;make install

安装GCC

cd ../../gcc* ;mkdir build && cd build  
../configure --prefix=/usr/local/gcc4.9.2 --enable-checking=release --with-gmp=/usr/local/gcc4.9.2 --with-mpfr=/usr/local/gcc4.9.2 --with-mpc=/usr/local/gcc4.9.2 --program-suffix=4.9.2

可以只需要特定语言，可以加个选项：--enable-languages=c,c++,fortran

接着：make最后：make install

配置环境变量export GCC_HOME=/usr/local/gcc4.9.2export PATH=$GCC_HOME/bin:/usr/local/bin:$PG_HOME/bin:$FIREBIRD_HOME/bin:$PATH

gcc4.9.2 for osx