无法安装g++-10

Question

运行Ubuntu 18.04。我增加了ppa:/test。

我成功地安装了gcc-10：

$ sudo apt-get install gcc-10
Reading package lists... Done
Building dependency tree
Reading state information... Done
gcc-10 is already the newest version (10.1.0-2ubuntu1~18.04).

我还安装了g++-7：

$ sudo apt-get install g++-7
Reading package lists... Done
Building dependency tree
Reading state information... Done
g++-7 is already the newest version (7.5.0-3ubuntu1~18.04).

我无法安装g++-10：

$ sudo apt-get install g++-10
Reading package lists... Done
Building dependency tree
Reading state information... Done
Note, selecting 'clang-10-examples' for regex 'g++-10'
Note, selecting 'clang-10' for regex 'g++-10'
Note, selecting 'libclang-10-dev' for regex 'g++-10'
Note, selecting 'python-clang-10' for regex 'g++-10'
Note, selecting 'clang-10-doc' for regex 'g++-10'
Note, selecting 'python3-clang-10' for regex 'g++-10'
clang-10 is already the newest version (1:10.0.0-4ubuntu1~18.04.1).
clang-10-doc is already the newest version (1:10.0.0-4ubuntu1~18.04.1).
clang-10-examples is already the newest version (1:10.0.0-4ubuntu1~18.04.1).
libclang-10-dev is already the newest version (1:10.0.0-4ubuntu1~18.04.1).
python3-clang-10 is already the newest version (1:10.0.0-4ubuntu1~18.04.1).

有什么问题吗？

编辑：

在执行apt-get update && apt-get upgrade之后：

$ apt policy '^gcc-10使用普通查询g++-10运行该命令将显示与regex匹配的每个包，但不显示g++10。 '^g\+\+-10使用普通查询D5运行该命令将显示与regex匹配的每个包，但不显示g++10。
gcc-10:
  Installed: 10.1.0-2ubuntu1~18.04
  Candidate: 10.1.0-2ubuntu1~18.04
  Version table:
 *** 10.1.0-2ubuntu1~18.04 500
        500 http://ppa.launchpad.net/ubuntu-toolchain-r/test/ubuntu bionic/main amd64 Packages
        100 /var/lib/dpkg/status
N: Unable to locate package ^g\+\+-10$
N: Couldn't find any package by regex '^g\+\+-10使用普通查询D5运行该命令将显示与regex匹配的每个包，但不显示g++10。

使用普通查询D5运行该命令将显示与regex匹配的每个包，但不显示g++10。

Answer 1

问题是我在工作的计算机是由木偶管理的。我一点也不知道。

显然，IT部门的某些人最近改变了中心配置。现在小狗移除我的PPA和强制安装某些软件包的特定版本不时。