Bug#955039: llvm-dev doesn't ensure that the corresponding clang is installed

[Iain Lane]

Package: llvm-dev
Version: 1:10.0-50~exp1
Severity: normal

Hi there,

Please see the attached build log. It's from mozjs68 which has
Build-Depends: llvm-dev, clang.

  Get: 73 https://mirrors.wikimedia.org/debian unstable/main s390x clang-10 s390x 1:10.0.0-1 [104 kB]
  Get: 74 https://mirrors.wikimedia.org/debian experimental/main s390x clang s390x 1:10.0-50~exp1 [8132 B]
  ...
  Get: 97 https://mirrors.wikimedia.org/debian experimental/main s390x libclang-dev s390x 1:10.0-50~exp1 [7756 B]
  ...
  Get: 116 https://mirrors.wikimedia.org/debian unstable/main s390x llvm-9-tools s390x 1:9.0.1-10 [322 kB]
  Get: 117 https://mirrors.wikimedia.org/debian unstable/main s390x llvm-9-dev s390x 1:9.0.1-10 [25.2 MB]
  Get: 118 https://mirrors.wikimedia.org/debian unstable/main s390x llvm-dev s390x 1:9.0-49.1 [8052 B

and then later on the build failed with:

  ERROR: The file /usr/lib/llvm-9/bin/clang returned by `llvm-config --bindir` does not exist.

It ultimately happened because of #954826 meaning clang-9 is
uninstallable ATM. But it would be good if the packaging of llvm could
somehow ensure that the matching clang is always installed - in this
case, it would have required installing llvm-10-dev. I don't actually
see how to achieve this in consuming packages.

Cheers,

-- 
Iain Lane                                  [ iain at orangesquash.org.uk ]
Debian Developer                                   [ laney at debian.org ]
Ubuntu Developer                                   [ laney at ubuntu.com ]