On Thu, Feb 17, 2022 at 11:40 AM Yonghong Song <yhs@xxxxxx> wrote:
>
> Build the kernel and selftest with clang compiler with LLVM=1,
> make -j LLVM=1
> make -C tools/testing/selftests/bpf -j LLVM=1
>
> I hit the following selftests/bpf compilation error:
> In file included from test_cpp.cpp:3:
> /.../tools/testing/selftests/bpf/tools/include/bpf/libbpf.h:73:8:
> error: 'relaxed_core_relocs' is deprecated: libbpf v0.6+: field has no effect [-Werror,-Wdeprecated-declarations]
> struct bpf_object_open_opts {
> ^
> test_cpp.cpp:56:2: note: in implicit move constructor for 'bpf_object_open_opts' first required here
> LIBBPF_OPTS(bpf_object_open_opts, opts);
> ^
> /.../tools/testing/selftests/bpf/tools/include/bpf/libbpf_common.h:77:3: note: expanded from macro 'LIBBPF_OPTS'
> (struct TYPE) { \
> ^
> /.../tools/testing/selftests/bpf/tools/include/bpf/libbpf.h:90:2: note: 'relaxed_core_relocs' has been explicitly marked deprecated here
> LIBBPF_DEPRECATED_SINCE(0, 6, "field has no effect")
> ^
> /.../tools/testing/selftests/bpf/tools/include/bpf/libbpf_common.h:24:4: note: expanded from macro 'LIBBPF_DEPRECATED_SINCE'
> (LIBBPF_DEPRECATED("libbpf v" # major "." # minor "+: " msg))
> ^
> /.../tools/testing/selftests/bpf/tools/include/bpf/libbpf_common.h:19:47: note: expanded from macro 'LIBBPF_DEPRECATED'
> #define LIBBPF_DEPRECATED(msg) __attribute__((deprecated(msg)))
>
> There are two ways to fix the issue, one is to use GCC diagnostic ignore pragma, and the
> other is to open code bpf_object_open_opts instead of using LIBBPF_OPTS.
> Since in general LIBBPF_OPTS is preferred, the patch fixed the issue by
> adding proper GCC diagnostic ignore pragmas.
>
> Signed-off-by: Yonghong Song <yhs@xxxxxx>
> ---
Do you know why we see this only with Clang? Why GCC doesn't generate this?
> tools/testing/selftests/bpf/test_cpp.cpp | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/tools/testing/selftests/bpf/test_cpp.cpp b/tools/testing/selftests/bpf/test_cpp.cpp
> index 773f165c4898..19ad172036da 100644
> --- a/tools/testing/selftests/bpf/test_cpp.cpp
> +++ b/tools/testing/selftests/bpf/test_cpp.cpp
> @@ -1,6 +1,9 @@
> /* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
> #include <iostream>
> +#pragma GCC diagnostic push
> +#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
> #include <bpf/libbpf.h>
> +#pragma GCC diagnostic pop
> #include <bpf/bpf.h>
> #include <bpf/btf.h>
> #include "test_core_extern.skel.h"
> --
> 2.30.2
>
