# Ubuntu下安装GCC
为了支持新的c++标准，需要安装新的GCC，安装步骤如下.
# 查看官方安装指导
GCC版本查看,截止20240324，gcc最新的版本为13.2，支持到了c++23标准。
版本发布信息可以参考：GCC Releases (opens new window)查看。
安装指导参考的网页为:【GCC Installation Instructions (opens new window)】
- 检查安装依赖,
- 下载源码，可使用
git命令克隆
git clone git://gcc.gnu.org/git/gcc.git
# 查看所有分支
git branch -a
# 查看所有标签
git tag -l
有时候，国内访问gcc放置代码的git仓库速度会很慢，这个时候可以从开源中国的码云平台上下载，
https://gitee.com/mirrors/gcc.git
这个是国内镜像，可以加速下载速度。
- 下载源码后，切入源码目录，执行如下命令下载依赖
./contrib/download_prerequisites
- 配置，可在源码仓库下新建
build目录，然后切换到build目录下执行如下命令进行配置。
../configure --enable-languages=c,c++ --prefix=/usr/local/gcc-13.2.0 --host=x86_64-pc-linux-gnu --prefix=/home/xx/data/sw/gcc13 --disable-multilib
更多的配置参数可以参考页面https://gcc.gnu.org/install/configure.html (opens new window)
- 安装
make -j4
sudo make install
- 验证安装
/usr/local/gcc-13.2.0/bin/gcc --version
- 设置环境变量
export PATH=$PATH:/usr/local/gcc-13.2.0/bin
- 卸载
sudo rm -rf /usr/local/gcc-13.2.0
# 错误
# 缺少gmp库
xx@xx-rob:~/data/code/gcc$ ./configure --enable-languages=c,c++ --prefix=/usr/local/gcc-13.2.
checking for the correct version of gmp.h... no
configure: error: Building GCC requires GMP 4.2+, MPFR 3.1.0+ and MPC 0.8.0+.
Try the --with-gmp, --with-mpfr and/or --with-mpc options to specify
their locations. Source code for these libraries can be found at
their respective hosting sites as well as at
解决方法，先执行命令：
xx@xx-rob:~/data/code/gcc$ ./contrib/download_prerequisites
2024-03-21 22:31:18 URL:http://gcc.gnu.org/pub/gcc/infrastructure/gmp-6.2.1.tar.bz2 [2493916/2493916] -> "gmp-6.2.1.tar.bz2" [1]
2024-03-21 22:33:48 URL:http://gcc.gnu.org/pub/gcc/infrastructure/mpfr-4.1.0.tar.bz2 [1747243/1747243] -> "mpfr-4.1.0.tar.bz2" [1]
2024-03-21 22:34:29 URL:http://gcc.gnu.org/pub/gcc/infrastructure/mpc-1.2.1.tar.gz [838731/838731] -> "mpc-1.2.1.tar.gz" [1]
2024-03-21 22:35:49 URL:http://gcc.gnu.org/pub/gcc/infrastructure/isl-0.24.tar.bz2 [2261594/2261594] -> "isl-0.24.tar.bz2" [1]
gmp-6.2.1.tar.bz2: OK
mpfr-4.1.0.tar.bz2: OK
mpc-1.2.1.tar.gz: OK
isl-0.24.tar.bz2: OK
All prerequisites downloaded successfully.
# 缺少32位开发库libc
/usr/bin/ld: cannot find -lgcc
collect2: error: ld returned 1 exit status
configure: error: I suspect your system does not have 32-bit development libraries (libc and headers). If you have them, rerun configure with --enable-multilib. If you do not have them, and want to build a 64-bit-only compiler, rerun configure with --disable-multilib.
解决办法：
- 安装
32位libc库文件 ./configure时使用参数--disable-multilib禁用编译32位平台上可以使用的库
# g++: error: gengtype-lex.c: No such file or directory
编译过程中报错：
> and I found the Makefile in my objdir directory. I try `make -j4` and found
> g++: error: gengtype-lex.c: No such file or directory
> g++: fatal error: no input files
> Could you help me with this?
解决办法：
缺少flex库文件，手动安装：
sudo apt-get install flex
# 编译报错：libstdc++.so.6: version `GLIBCXX_3.4.20' not found
# lib/libstdc++.so.6: version `GLIBCXX_3.4.20' not found (required by /usr/lib/x86_64-linux-gnu/libproxy.so.1)
# Failed to load module: /usr/lib/x86_64-linux-gnu/gio/modules/libgiolibproxy.so
运行程序时报以上错误，这说明GCC使用的依赖库太老了，可以使用以下命令查看c++库支持的GLIBCXX版本，
strings /usr/lib/libstdc++.so.6 | grep GLIBCXX
解决办法，安装新版本的gcc，并在新版本的lib64文件夹下找到libstdc++库文件，将该路径添加到链接库路径:
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/cur/xx
# reference
1.https://www.spinics.net/lists/gcchelp/msg50998.html (opens new window)
2.https://stackoverflow.com/questions/44773296/libstdc-so-6-version-glibcxx-3-4-20-not-found (opens new window)