为c++20安装g++-9

Question

我想运行全功能 of c++20 on g++。但是，我需要为此目的安装g++-9。

在安装导轨之后，g++的旧版本不适用于g++-9。

有什么暗示吗？

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.

Answer 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