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bpftool: Use __typeof__() instead of typeof() in BPF skeleton

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When generated BPF skeleton header is included in C++ code base, some
compiler setups will emit warning about using language extensions due to
typeof() usage, resulting in something like:

  error: extension used [-Werror,-Wlanguage-extension-token]
  obj->struct_ops.empty_tcp_ca = (typeof(obj->struct_ops.empty_tcp_ca))
                                  ^

It looks like __typeof__() is a preferred way to do typeof() with better
C++ compatibility behavior, so switch to that. With __typeof__() we get
no such warning.

Fixes: c2a0257c1edf ("bpftool: Cast pointers for shadow types explicitly.")
Fixes: 00389c58ffe9 ("bpftool: Add support for subskeletons")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Kui-Feng Lee <thinker.li@gmail.com>
Acked-by: Quentin Monnet <qmo@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20240401170713.2081368-1-andrii@kernel.org
This commit is contained in:
Andrii Nakryiko 2024-04-01 10:07:13 -07:00 committed by Daniel Borkmann
parent 965c6167c9
commit 2a24e24857
1 changed files with 2 additions and 2 deletions
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4
tools/bpf/bpftool/gen.c
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@ -386,7 +386,7 @@ static int codegen_subskel_datasecs(struct bpf_object *obj, const char *obj_name
*/
needs_typeof = btf_is_array(var) || btf_is_ptr_to_func_proto(btf, var);
if (needs_typeof)
printf("typeof(");
printf("__typeof__(");
err = btf_dump__emit_type_decl(d, var_type_id, &opts);
if (err)
@ -1131,7 +1131,7 @@ static void gen_st_ops_shadow_init(struct btf *btf, struct bpf_object *obj)
continue;
codegen("\
\n\
obj->struct_ops.%1$s = (typeof(obj->struct_ops.%1$s))\n\
obj->struct_ops.%1$s = (__typeof__(obj->struct_ops.%1$s))\n\
bpf_map__initial_value(obj->maps.%1$s, NULL);\n\
\n\
", ident);