我想运行全部功能的。但是，c++20为此g++我需要安装g++-9。
安装后指南旧版本的g++不适用于g++-9。
有什么提示吗？
sudo apt install g++-9
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Unable to locate package g++-9
E: Couldn't find any package by regex 'g++-9'
。
sudo apt install g++9
Reading package lists... Done
Building dependency tree
Reading state information... Done
Note, selecting 'libconfig9' for regex 'g++9'
Note, selecting 'libaac-tactics-ocaml-ibg92' for regex 'g++9'
Note, selecting 'libounit-ocaml-dev-afg95:i386' for regex 'g++9'
Note, selecting 'libjpeg9-dbg' for regex 'g++9'
Note, selecting 'libjpeg9-dev' for regex 'g++9'
Note, selecting 'libreins-ocaml-dev-rpyg9' for regex 'g++9'
Note, selecting 'libaac-tactics-ocaml-dev-ibg92' for regex 'g++9'
Note, selecting 'libjpeg9' for regex 'g++9'
Note, selecting 'libflac-ocaml-77yg9:i386' for regex 'g++9'
Note, selecting 'libflac-ocaml-dev-77yg9:i386' for regex 'g++9'
Note, selecting 'libaac-tactics-ocaml' instead of 'libaac-tactics-ocaml-ibg92'
Note, selecting 'libaac-tactics-ocaml-dev' instead of 'libaac-tactics-ocaml-dev-ibg92'
Note, selecting 'libreins-ocaml-dev' instead of 'libreins-ocaml-dev-rpyg9'
Note, selecting 'libflac-ocaml:i386' instead of 'libflac-ocaml-77yg9:i386'
Note, selecting 'libflac-ocaml-dev:i386' instead of 'libflac-ocaml-dev-77yg9:i386'
Note, selecting 'libounit-ocaml-dev:i386' instead of 'libounit-ocaml-dev-afg95:i386'
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
libaac-tactics-ocaml : Depends: libcoq-ocaml-d91z1
Depends: ocaml-base-nox-4.02.3
Recommends: libaac-tactics-coq but it is not going to be installed
libaac-tactics-ocaml-dev : Depends: camlp5-tli55
Depends: libcoq-ocaml-dev-d91z1
Depends: ocaml-nox-4.02.3
libflac-ocaml-dev:i386 : Depends: libogg-ocaml-dev-465c2:i386
Depends: ocaml-nox-4.02.3:i386
Depends: libogg-ocaml-dev:i386 but it is not going to be installed
libounit-ocaml-dev:i386 : Depends: ocaml-nox-4.02.3:i386
libreins-ocaml-dev : Depends: ocaml-nox-4.02.3
E: Unable to correct problems, you have held broken packages.
答案1
安装 g++ 8
sudo apt install g++-8
使用 c++ 20 版本运行 g++-8。
g++-8 -std=c++2a text.c++ -o compiled