Re: [PATCH for-4.15] automation/alpine: add g++ to the list of build depends

[Jan Beulich <jbeulich@xxxxxxxx>]

On 02.03.2021 09:14, Roger Pau Monné wrote:
> On Mon, Mar 01, 2021 at 06:01:36PM +0000, Andrew Cooper wrote:
>> On 01/03/2021 17:59, Andrew Cooper wrote:
>>> On 01/03/2021 09:58, Roger Pau Monne wrote:
>>>> clang++ relies on the C++ headers installed by g++, or else a clang
>>>> build will hit the following error:
>>>>
>>>> <built-in>:3:10: fatal error: 'cstring' file not found
>>>> #include "cstring"
>>>>          ^~~~~~~~~
>>>> 1 error generated.
>>>> make[10]: *** [Makefile:120: headers++.chk] Error 1
>>>>
>>>> Reported-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
>>>> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
>>>> ---
>>>> Cc: Ian Jackson <iwj@xxxxxxxxxxxxxx>
>>>> No real risk here from a release PoV, it's just pulling a package
>>>> required for the Alpine clang build. Worse that cold happen is that
>>>> the Alpine clang build broke, but it's already broken.
>>> Shouldn't this be fixed upstream in Alpine?  Its clearly a packaging bug.
>>
>> Or (thinking about it), we've got a build system bug using g++ when it
>> should be using clang++.
> 
> No, the check is using clang++, the issue is that clang++ doesn't
> install the standard c++ headers, and thus trying to use them (cstring
> in this case) fails. Installing the g++ package solves the issue
> because it installs the headers.

I have to admit that I consider this odd. The g++ package should
neither provide nor depend on the headers. It may recommend their
installation. On my distro (SLES) the headers come from the
libstdc++-devel package, as I would have expected. There
additionally is a dependency of libclang5 (no -devel suffix!) on
libstdc++-devel (I suppose this is an indication that things
aren't quite right here either; I haven't checked an up-to-date
version of the distro yet, though).

Jan