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Date:   Sat, 23 Nov 2019 01:47:34 +0200
From:   Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org>
To:     Stanislav Fomichev <sdf@fomichev.me>
Cc:     Andrii Nakryiko <andrii.nakryiko@gmail.com>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Yonghong Song <yhs@fb.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <jakub.kicinski@netronome.com>,
        Jesper Dangaard Brouer <hawk@kernel.org>,
        john fastabend <john.fastabend@gmail.com>,
        open list <linux-kernel@vger.kernel.org>,
        Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
        clang-built-linux@googlegroups.com, ilias.apalodimas@linaro.org,
        sergei.shtylyov@cogentembedded.com,
        Andrii Nakryiko <andriin@fb.com>
Subject: Re: [PATCH v5 bpf-next 11/15] libbpf: don't use cxx to test_libpf
 target
Message-ID: <20191122234733.GA2474@khorivan>
Mail-Followup-To: Stanislav Fomichev <sdf@fomichev.me>,
        Andrii Nakryiko <andrii.nakryiko@gmail.com>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>, Yonghong Song <yhs@fb.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <jakub.kicinski@netronome.com>,
        Jesper Dangaard Brouer <hawk@kernel.org>,
        john fastabend <john.fastabend@gmail.com>,
        open list <linux-kernel@vger.kernel.org>,
        Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
        clang-built-linux@googlegroups.com, ilias.apalodimas@linaro.org,
        sergei.shtylyov@cogentembedded.com,
        Andrii Nakryiko <andriin@fb.com>
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On Fri, Nov 22, 2019 at 08:32:11AM -0800, Stanislav Fomichev wrote:
>On 11/21, Andrii Nakryiko wrote:
>> On Thu, Nov 21, 2019 at 1:42 PM Stanislav Fomichev <sdf@fomichev.me> wrote:
>> >
>> > On 10/11, Ivan Khoronzhuk wrote:
>> > > No need to use C++ for test_libbpf target when libbpf is on C and it
>> > > can be tested with C, after this change the CXXFLAGS in makefiles can
>> > > be avoided, at least in bpf samples, when sysroot is used, passing
>> > > same C/LDFLAGS as for lib.
>> > > Add "return 0" in test_libbpf to avoid warn, but also remove spaces at
>> > > start of the lines to keep same style and avoid warns while apply.
>> > Hey, just spotted this patch, not sure how it slipped through.
>> > The c++ test was there to make sure libbpf can be included and
>> > linked against c++ code (i.e. libbpf headers don't have some c++
>> > keywords/etc).
>> >
>> > Any particular reason you were not happy with it? Can we revert it
>> > back to c++ and fix your use-case instead? Alternatively, we can just
>> > remove this test if we don't really care about c++.
>> >
>>
>> No one seemed to know why we have C++ pieces in pure C library and its
>> Makefile, so we decide to "fix" this. :)
>It's surprising, the commit 8c4905b995c6 clearly states the reason
>for adding it. Looks like it deserved a real comment in the Makefile :-)

I dislike changing things like this, but I was asked while review and
it seemed logical enough. The comment could prevent us from doing this.

>
>> But I do understand your concern. Would it be possible to instead do
>> this as a proper selftests test? Do you mind taking a look at that?
>Ack, will move this test_libbpf.c into selftests and convert back to
>c++.

-- 
Regards,
Ivan Khoronzhuk