在我的 Ubuntu 18.04 LTS 中：
marco@PC:~$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 18.04.1 LTS
Release: 18.04
Codename: bionic
我有 gcc 7.3.0 版：
marco@PC:~$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/7/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu
7.3.0-21ubuntu1~16.04' --with-bugurl=file:///usr/share/doc/gcc-
7/README.Bugs --enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++
--prefix=/usr --with-gcc-major-version-only --program-suffix=-7
--program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-
id --libexecdir=/usr/lib --without-included-gettext --enable-
threads=posix --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-
clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-
default-libstdcxx-abi=new --enable-gnu-unique-object --disable-vtable-
verify --enable-libmpx --enable-plugin --with-system-zlib --with-target-
system-zlib --enable-objc-gc=auto --enable-multiarch --disable-werror
--with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32
--enable-multilib --with-tune=generic --enable-offload-targets=nvptx-none
--without-cuda-driver --enable-checking=release --build=x86_64-linux-gnu
--host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 7.3.0 (Ubuntu 7.3.0-21ubuntu1~16.04)
我想安装 gcc-8：
marco@PC:~$ sudo apt-get install gcc-8
[sudo] password for marco:
Reading package lists... Done
Building dependency tree
Reading state information... Done
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:
gcc-8 : Depends: cpp-8 (= 8.1.0-1ubuntu1) but it is not going to be
installed
Depends: gcc-8-base (= 8.1.0-1ubuntu1) but 8.1.0-5ubuntu1~16.04
is to be installed
Depends: libgcc-8-dev (= 8.1.0-1ubuntu1) but it is not going to
be installed
E: Unable to correct problems, you have held broken packages.
按照此处找到的提示询问Ubuntu：无法纠正问题，您持有损坏的软件包
marco@PC:~$ sudo apt-get update
[sudo] password for marco:
Hit:1 http://security.ubuntu.com/ubuntu bionic-security InRelease
Hit:2 http://cz.archive.ubuntu.com/ubuntu bionic InRelease
Hit:3 http://us.archive.ubuntu.com/ubuntu bionic InRelease
Get:4 http://us.archive.ubuntu.com/ubuntu bionic-updates InRelease [88.7 kB]
Hit:5 http://us.archive.ubuntu.com/ubuntu bionic-backports InRelease
Fetched 88.7 kB in 1s (107 kB/s)
Reading package lists... Done
marco@PC:~$ sudo apt-get autoremove
Reading package lists... Done
Building dependency tree
Reading state information... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
marco@PC:~$ dpkg --get-selections | grep hold
marco@PC:~$ sudo apt-get upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
marco@PC:~$ sudo apt-get update
Hit:1 http://security.ubuntu.com/ubuntu bionic-security InRelease
Hit:2 http://cz.archive.ubuntu.com/ubuntu bionic InRelease
Hit:3 http://us.archive.ubuntu.com/ubuntu bionic InRelease
Get:4 http://us.archive.ubuntu.com/ubuntu bionic-updates InRelease [88.7 kB]
Hit:5 http://us.archive.ubuntu.com/ubuntu bionic-backports InRelease
Fetched 88.7 kB in 1s (123 kB/s)
Reading package lists... Done
然后，我按照建议检查了使用的 PPA 存储库：
marco@PC:~$ apt-cache policy gcc-8 cpp-8 libgcc-8-dev
gcc-8:
Installed: (none)
Candidate: 8.1.0-1ubuntu1
Version table:
8.1.0-1ubuntu1 500
500 http://ppa.launchpad.net/ubuntu-toolchain-r/test/ubuntu
bionic/main amd64 Packages
8-20180414-1ubuntu2 500
500 http://us.archive.ubuntu.com/ubuntu bionic/universe amd64
Packages
cpp-8:
Installed: (none)
Candidate: 8.1.0-1ubuntu1
Version table:
8.1.0-1ubuntu1 500
500 http://ppa.launchpad.net/ubuntu-toolchain-r/test/ubuntu
bionic/main amd64 Packages
8-20180414-1ubuntu2 500
500 http://us.archive.ubuntu.com/ubuntu bionic/universe amd64
Packages
libgcc-8-dev:
Installed: (none)
Candidate: 8.1.0-1ubuntu1
Version table:
8.1.0-1ubuntu1 500
500 http://ppa.launchpad.net/ubuntu-toolchain-r/test/ubuntu
bionic/main amd64 Packages
8-20180414-1ubuntu2 500
500 http://us.archive.ubuntu.com/ubuntu bionic/universe amd64
Packages
然后我删除了 PPA ubuntu-toolchain-r/test ：
sudo add-apt-repository --remove ppa:ubuntu-toolchain-r/test
Toolchain test builds; see https://wiki.ubuntu.com/ToolChain
More info: https://launchpad.net/~ubuntu-toolchain-r/+archive/ubuntu/test
Press [ENTER] to continue or Ctrl-c to cancel removing it.
但问题依然存在：
marco@PC:~$ sudo apt-get install gcc-8
Reading package lists... Done
Building dependency tree
Reading state information... Done
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:
gcc-8 : Depends: cpp-8 (= 8-20180414-1ubuntu2) but it is not going to be
installed
Depends: gcc-8-base (= 8-20180414-1ubuntu2) but 8.1.0-5ubuntu1~16.04
is to be installed
Depends: libgcc-8-dev (= 8-20180414-1ubuntu2) but it is not going to
be installed
E: Unable to correct problems, you have held broken packages.
marco@PC:~$ sudo apt-get install cpp-8
Reading package lists... Done
Building dependency tree
Reading state information... Done
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:
cpp-8 : Depends: gcc-8-base (= 8.1.0-1ubuntu1) but 8.1.0-5ubuntu1~16.04
is to be installed
E: Unable to correct problems, you have held broken packages.
marco@PC:~$ sudo apt-get install gcc-8-base
Reading package lists... Done
Building dependency tree
Reading state information... Done
gcc-8-base is already the newest version (8.1.0-5ubuntu1~16.04).
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
marco@PC:~$ sudo apt-get install libgcc-8-dev
Reading package lists... Done
Building dependency tree
Reading state information... Done
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:
libgcc-8-dev : Depends: gcc-8-base (= 8.1.0-1ubuntu1) but
8.1.0-5ubuntu1~16.04 is to be installed
Depends: libasan5 (>= 8.1.0-1ubuntu1) but it is not going
to be installed
Depends: libubsan1 (>= 8.1.0-1ubuntu1) but it is not
going to be installed
E: Unable to correct problems, you have held broken packages.
marco@PC:~$ sudo apt-get install libasan5
Reading package lists... Done
Building dependency tree
Reading state information... Done
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:
libasan5 : Depends: gcc-8-base (= 8.1.0-1ubuntu1) but
8.1.0-5ubuntu1~16.04 is to be installed
E: Unable to correct problems, you have held broken packages.
marco@PC:~$ sudo apt-get install libubsan1
Reading package lists... Done
Building dependency tree
Reading state information... Done
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:
libubsan1 : Depends: gcc-8-base (= 8.1.0-1ubuntu1) but
8.1.0-5ubuntu1~16.04 is to be installed
E: Unable to correct problems, you have held broken packages.
所以......似乎为了安装 gcc-8 我必须安装其他依赖于其他包的包，这些包依赖于已经正确安装的 gcc-8-base。
它说“破损的包裹”......那么如何解决这个问题？期待您的善意提示和帮助。马可
更新：
marco@PC:~$ sudo apt-get install ppa-purge
Reading package lists... Done
Building dependency tree
Reading state information... Done
ppa-purge is already the newest version (0.2.8+bzr63).
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
marco@PC:~$ sudo ppa-purge ppa:ubuntu-toolchain-r/test
Updating packages lists
PPA to be removed: ubuntu-toolchain-r test
Warning: Could not find package list for PPA: ubuntu-toolchain-r test
marco@PC:~$ sudo apt-get update
Hit:1 http://cz.archive.ubuntu.com/ubuntu bionic InRelease
Hit:2 http://us.archive.ubuntu.com/ubuntu bionic InRelease
Hit:3 http://security.ubuntu.com/ubuntu bionic-security InRelease
Hit:4 http://us.archive.ubuntu.com/ubuntu bionic-updates InRelease
Hit:5 http://us.archive.ubuntu.com/ubuntu bionic-backports InRelease
Reading package lists... Done
marco@PC:~$ sudo apt install gcc-8-base gcc-8 cpp-8 libgcc-8-dev
Reading package lists... Done
Building dependency tree
Reading state information... Done
gcc-8-base is already the newest version (8.1.0-5ubuntu1~16.04).
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:
cpp-8 : Depends: gcc-8-base (= 8-20180414-1ubuntu2) but 8.1.0-5ubuntu1~16.04
is to be installed
gcc-8 : Depends: gcc-8-base (= 8-20180414-1ubuntu2) but 8.1.0-5ubuntu1~16.04
is to be installed
libgcc-8-dev : Depends: gcc-8-base (= 8-20180414-1ubuntu2) but
8.1.0-5ubuntu1~16.04 is to be installed
Depends: libasan5 (>= 8-20180414-1ubuntu2) but it is not
going to be installed
Depends: libubsan1 (>= 8-20180414-1ubuntu2) but it is not
going to be installed
E: Unable to correct problems, you have held broken packages.
安装 aptitude 后，我按照 aptitude 指示的建议进行操作。现在我有这种情况：
marco@PC:~$ sudo update-alternatives --config gcc
There are 2 choices for the alternative gcc (providing /usr/bin/gcc).
Selection Path Priority Status
------------------------------------------------------------
* 0 /usr/bin/gcc-7 700 auto mode
1 /usr/bin/gcc-7 700 manual mode
2 /usr/bin/gcc-8 80 manual mode
marco@PC:~$ g++ -std=c++17 HelloWorld.cpp -oHelloWorld
marco@PC:~$ ./HelloWorld
Hello World!
如果我选择使用 gcc-8 ：
marco@PC:~$ sudo update-alternatives --config gcc
There are 2 choices for the alternative gcc (providing /usr/bin/gcc).
Selection Path Priority Status
------------------------------------------------------------
* 0 /usr/bin/gcc-7 700 auto mode
1 /usr/bin/gcc-7 700 manual mode
2 /usr/bin/gcc-8 80 manual mode
Press <enter> to keep the current choice[*], or type selection number: 2
update-alternatives: using /usr/bin/gcc-8 to provide /usr/bin/gcc (gcc) in
manual mode
update-alternatives: warning: skip creation of /usr/bin/g++ because
associated file /usr/bin/g++-8 (of link group gcc) doesn't exist
marco@PC:~$ sudo aptitude install g++-8
The following NEW packages will be installed:
g++-8 libstdc++-8-dev{a}
0 packages upgraded, 2 newly installed, 0 to remove and 0 not upgraded.
Need to get 9,623 kB of archives. After unpacking 43.7 MB will be used.
Do you want to continue? [Y/n/?] Y
Get: 1 http://us.archive.ubuntu.com/ubuntu bionic/universe amd64 libstdc++-8-
dev amd64 8-20180414-1ubuntu2 [1,536 kB]
Get: 2 http://us.archive.ubuntu.com/ubuntu bionic/universe amd64 g++-8 amd64
8-20180414-1ubuntu2 [8,088 kB]
Fetched 9,623 kB in 1s (7,165 kB/s)
Selecting previously unselected package libstdc++-8-dev:amd64.
(Reading database ... 92421 files and directories currently installed.)
Preparing to unpack .../libstdc++-8-dev_8-20180414-1ubuntu2_amd64.deb ...
Unpacking libstdc++-8-dev:amd64 (8-20180414-1ubuntu2) ...
Selecting previously unselected package g++-8.
Preparing to unpack .../g++-8_8-20180414-1ubuntu2_amd64.deb ...
Unpacking g++-8 (8-20180414-1ubuntu2) ...
Setting up libstdc++-8-dev:amd64 (8-20180414-1ubuntu2) ...
Setting up g++-8 (8-20180414-1ubuntu2) ...
Processing triggers for man-db (2.8.3-2) ...
marco@PC:~$ sudo update-alternatives --config gcc
There are 2 choices for the alternative gcc (providing /usr/bin/gcc).
Selection Path Priority Status
------------------------------------------------------------
0 /usr/bin/gcc-7 700 auto mode
1 /usr/bin/gcc-7 700 manual mode
* 2 /usr/bin/gcc-8 80 manual mode
Press <enter> to keep the current choice[*], or type selection number:
update-alternatives: warning: forcing reinstallation of alternative /usr/bin
/gcc-8 because link group gcc is broken
现在，重新启动后，它似乎工作：
marco@PC:~$ sudo update-alternatives --config gcc
There are 2 choices for the alternative gcc (providing /usr/bin/gcc).
Selection Path Priority Status
------------------------------------------------------------
0 /usr/bin/gcc-7 700 auto mode
1 /usr/bin/gcc-7 700 manual mode
* 2 /usr/bin/gcc-8 80 manual mode
Press <enter> to keep the current choice[*], or type selection number:
marco@PC:~$ g++ -std=c++17 HelloWorld.cpp -oHelloWorld
marco@PC:~$ ./HelloWorld
Hello World!
marco@PC:~$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/8/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu
8-20180414-1ubuntu2' --with-bugurl=file:///usr/share/doc/gcc-8/README.Bugs
--enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++ --prefix=/usr
--with-gcc-major-version-only --with-as=/usr/bin/x86_64-linux-gnu-as --with-
ld=/usr/bin/x86_64-linux-gnu-ld --program-suffix=-8 --program-prefix=x86_64-
linux-gnu- --enable-shared --enable-linker-build-id --libexecdir=/usr/lib
--without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-
nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-
libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-
object --disable-vtable-verify --enable-libmpx --enable-plugin --enable-
default-pie --with-system-zlib --with-target-system-zlib --enable-objc-
gc=auto --enable-multiarch --disable-werror --with-arch-32=i686 --with-
abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-
tune=generic --enable-offload-targets=nvptx-none --without-cuda-driver
--enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu
--target=x86_64-linux-gnu
Thread model: posix
gcc version 8.0.1 20180414 (experimental) [trunk revision 259383] (Ubuntu
8-20180414-1ubuntu2)
来自您的软件源的 16.04 不兼容的存储库会干扰在 Ubuntu 18.04 中安装其他软件包并导致有关损坏的软件包的错误消息，因此请从您的软件源中使用ppa-purge删除那些不兼容的存储库。
然后，您将能够从默认的 Ubuntu 18.04 存储库安装所需的软件包。打开终端并输入：
如果在运行最后一个命令后出现依赖问题，请遵循 aptitude 的建议，因为 aptitude 在建议如何解决由损坏的包引起的依赖问题方面有点聪明。