linux-stable/tools/lib
Andrii Nakryiko d6ea94068b libbpf: Avoid enum forward-declarations in public API in C++ mode
[ Upstream commit b42693415b ]

C++ enum forward declarations are fundamentally not compatible with pure
C enum definitions, and so libbpf's use of `enum bpf_stats_type;`
forward declaration in libbpf/bpf.h public API header is causing C++
compilation issues.

More details can be found in [0], but it comes down to C++ supporting
enum forward declaration only with explicitly specified backing type:

  enum bpf_stats_type: int;

In C (and I believe it's a GCC extension also), such forward declaration
is simply:

  enum bpf_stats_type;

Further, in Linux UAPI this enum is defined in pure C way:

enum bpf_stats_type { BPF_STATS_RUN_TIME = 0; }

And even though in both cases backing type is int, which can be
confirmed by looking at DWARF information, for C++ compiler actual enum
definition and forward declaration are incompatible.

To eliminate this problem, for C++ mode define input argument as int,
which makes enum unnecessary in libbpf public header. This solves the
issue and as demonstrated by next patch doesn't cause any unwanted
compiler warnings, at least with default warnings setting.

  [0] https://stackoverflow.com/questions/42766839/c11-enum-forward-causes-underlying-type-mismatch
  [1] Closes: https://github.com/libbpf/libbpf/issues/249

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20221130200013.2997831-1-andrii@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-12-31 13:26:46 +01:00
..
api Kbuild updates for v5.18 2022-03-31 11:59:03 -07:00
bpf libbpf: Avoid enum forward-declarations in public API in C++ mode 2022-12-31 13:26:46 +01:00
perf libperf evlist: Fix polling of system-wide events 2022-09-21 16:08:00 -03:00
subcmd libsubcmd: Fix OPTION_GROUP sorting 2022-04-22 12:32:01 +02:00
symbol
thermal tools/lib/thermal: remove unneeded semicolon 2022-05-19 12:11:52 +02:00
traceevent libtraceevent: Add __rel_loc relative location attribute support 2021-12-06 15:37:22 -05:00
argv_split.c
bitmap.c Bitmap patches for v6.0-rc1 2022-08-07 17:52:35 -07:00
ctype.c
find_bit.c tools: sync tools/bitmap with mother linux 2022-01-15 08:47:31 -08:00
hweight.c
list_sort.c
rbtree.c
slab.c tools: Move gfp.h and slab.h from radix-tree to lib 2022-02-20 08:44:37 +02:00
str_error_r.c
string.c
vsprintf.c
zalloc.c