[cfe-dev] Feedback about libc++ packaging / co installable or not in distros?

[Sylvestre Ledru via cfe-dev]

Hello,

Lately, Reshabh and myself have been working to integrate libc++ into the Debian & Ubuntu llvm-toolchains packages. A blog post is coming to explain in detail what it means.

First, we focussed on bringing libc++ into the packages. Now that we have, we are working to trying to make libc++ & libc++abi coinstalable.

However, starting the work, we are not sure it really makes sense.

Let’s take an example. For example, if I compile with the following command line:
clang++-8 -stdlib=libc++ -lc++abi foo.cpp -o o
it will use the headers in /usr/lib/llvm-8/include/ & the lib in /usr/lib/llvm-8/lib/

However, at run time, it will use the libc++.so.1 in the ld library path (probably in /lib/x86_64-linux-gnu/).

This also means that we can have a program built using libc++-7 but at runtime, it will use the libc++-8 as library. We are not sure it is such a great idea!

Otherwise, the other options is to be back marking the packages as conflicting with each others. This means that it won’t be possible on the same Debian & Ubuntu system to have libc++-7 and libc++abi-7 installed with libc++-8 and libc++abi-8.

Thanks
Sylvestre & Reshabh