[PATCH] selftests/bpf: ignore pointer types check with clang

[Andrea Righi <andrea.righi@xxxxxxxxxxxxx>]

Building bpf selftests with clang can trigger errors like the following:

  CLNG-BPF [test_maps] bpf_iter_netlink.bpf.o
progs/bpf_iter_netlink.c:32:4: error: incompatible pointer types assigning to 'struct sock *' from 'struct sock___17 *' [-Werror,-Wincompatible-pointer-types]
        s = &nlk->sk;
          ^ ~~~~~~~~
1 error generated.

This is due to the fact that bpftool emits duplicate data types with
different names in vmlinux.h (i.e., `struct sock` in this case) and
these types, despite having a different name, represent in fact the same
object.

Add -Wno-incompatible-pointer-types to CLANG_CLAGS to prevent these
errors.

Signed-off-by: Andrea Righi <andrea.righi@xxxxxxxxxxxxx>
---
 tools/testing/selftests/bpf/Makefile | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index b677dcd0b77a..0d9ef819a065 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -356,7 +356,8 @@ BPF_CFLAGS = -g -Werror -D__TARGET_ARCH_$(SRCARCH) $(MENDIAN) 		\
 	     -I$(abspath $(OUTPUT)/../usr/include)
 
 CLANG_CFLAGS = $(CLANG_SYS_INCLUDES) \
-	       -Wno-compare-distinct-pointer-types
+	       -Wno-compare-distinct-pointer-types \
+	       -Wno-incompatible-pointer-types
 
 $(OUTPUT)/test_l4lb_noinline.o: BPF_CFLAGS += -fno-inline
 $(OUTPUT)/test_xdp_noinline.o: BPF_CFLAGS += -fno-inline
-- 
2.39.2