Bug#848590: llvm-toolchain-3.9: libclang-3.9-dev is missing cmake files

[Gert Wollny]

Source: llvm-toolchain-3.9
Version: 3.9.1-1
Severity: normal

Dear Maintainers,

For someone who is compiling using libclang-3.9-dev the current way to detect
the installation location by using cmake is to use FIND_PACKAGE(LLVM), since
here the required infomation about the root include directory is provided. As I
understand it, the installation location of the clang-dev include files is
always relative to the reported LLVM_INCLUDES path, and hence one can rely on
this test if one wants to use clang on a system that always install all
llvm/clang related debvelopment files.

However, in Debian the llvm related cmake files are installed with
libllvm-X.Y-dev and this package does not depend on libclang-3.9-dev. Hence, if
libclang-3.9-dev is not installed, but libllvm-3.9-dev is, then automatic
package detection will run without reporting an error, but later compilation
fails because the clang header files are not in the expected location, i.e.
they are missing.

To resolcve this it would be good if either the with libllvm-3.9-dev provided
cmake files would also check whether the clang development headers are
available, or if these cmake files are installed in a way that pulls in both,
libllvm-3.9-dev and libclang-3.9-dev.

Many thanks,
Gert



-- System Information:
Debian Release: stretch/sid
  APT prefers unstable-debug
  APT policy: (500, 'unstable-debug'), (500, 'unstable'), (500, 'testing'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.8.0-2-amd64 (SMP w/2 CPU cores)
Locale: LANG=de_DE.UTF-8, LC_CTYPE=de_DE.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)