我正在尝试安装卡拉在 ubuntu 19.04 上，但它需要 clang-7 包。我尝试使用
sudo apt install clang-7
但是我收到了错误：
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:
clang-7 : Depends: libstdc++-5-dev but it is not installable
Depends: libgcc-5-dev but it is not installable
Depends: libobjc-5-dev but it is not installable
Recommends: llvm-7-dev but it is not going to be installed
Recommends: libomp-7-dev but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
我尝试通过以下方式修复损坏的软件包解决方案_1和解决方案_2，但并未解决问题。
最后我aptitude按照这个安装回答，并尝试通过以下方式安装 clang：
sudo aptitude install clang-7
但得到了以下输出：
The following NEW packages will be installed:
clang-7{b} libclang-common-7-dev{a} libclang1-7{a} libomp-7-dev{ab} libomp5-7{ab} llvm-7{a} llvm-7-dev{a} llvm-7-runtime{a}
0 packages upgraded, 8 newly installed, 0 to remove and 0 not upgraded.
Need to get 45,3 MB of archives. After unpacking 303 MB will be used.
The following packages have unmet dependencies:
libomp-7-dev : Conflicts: libomp-x.y-dev which is a virtual package, provided by:
- libomp-7-dev (1:7.1.0~svn353565-1~exp1~20190408084827.60), but 1:7.1.0~svn353565-1~exp1~20190408084827.60 is to be installed
- libomp-8-dev (1:8-3), but 1:8-3 is installed
- libomp-7-dev (1:7.0.1-8), but 1:7.1.0~svn353565-1~exp1~20190408084827.60 is to be installed
clang-7 : Depends: libstdc++-5-dev which is a virtual package and is not provided by any available package
Depends: libgcc-5-dev which is a virtual package and is not provided by any available package
Depends: libobjc-5-dev which is a virtual package and is not provided by any available package
libomp5-7 : Conflicts: libomp-x.y which is a virtual package, provided by:
- libomp5-7 (1:7.1.0~svn353565-1~exp1~20190408084827.60), but 1:7.1.0~svn353565-1~exp1~20190408084827.60 is to be installed
- libomp5-8 (1:8-3), but 1:8-3 is installed
- libomp5-7 (1:7.0.1-8), but 1:7.1.0~svn353565-1~exp1~20190408084827.60 is to be installed
libomp5-8 : Conflicts: libomp-x.y which is a virtual package, provided by:
- libomp5-7 (1:7.1.0~svn353565-1~exp1~20190408084827.60), but 1:7.1.0~svn353565-1~exp1~20190408084827.60 is to be installed
- libomp5-8 (1:8-3), but 1:8-3 is installed
- libomp5-7 (1:7.0.1-8), but 1:7.1.0~svn353565-1~exp1~20190408084827.60 is to be installed
libomp-8-dev : Conflicts: libomp-x.y-dev which is a virtual package, provided by:
- libomp-7-dev (1:7.1.0~svn353565-1~exp1~20190408084827.60), but 1:7.1.0~svn353565-1~exp1~20190408084827.60 is to be installed
- libomp-8-dev (1:8-3), but 1:8-3 is installed
- libomp-7-dev (1:7.0.1-8), but 1:7.1.0~svn353565-1~exp1~20190408084827.60 is to be installed
The following actions will resolve these dependencies:
Keep the following packages at their current version:
1) clang-7 [Not Installed]
2) libomp-7-dev [Not Installed]
3) libomp5-7 [Not Installed]
Accept this solution? [Y/n/q/?]
No packages will be installed, upgraded, or removed.
0 packages upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Need to get 0 B of archives. After unpacking 0 B will be used.
请指导我在 Ubuntu 19.04 上安装 clang-7 并帮助我。