Jakub reports build failures when merging linux/master with net tree:
CXX test_cpp
In file included from <built-in>:454:
<command line>:2:9: error: '_GNU_SOURCE' macro redefined [-Werror,-Wmacro-redefined]
2 | #define _GNU_SOURCE
| ^
<built-in>:445:9: note: previous definition is here
445 | #define _GNU_SOURCE 1
The culprit is commit cc937dad85ae ("selftests: centralize -D_GNU_SOURCE= to
CFLAGS in lib.mk") which unconditionally added -D_GNU_SOUCE to CLFAGS.
Apparently clang++ also unconditionally adds it for the C++ targets [0]
which causes a conflict. Add small change in the selftests makefile
to filter it out for test_cpp.
Not sure which tree it should go via, targeting bpf for now, but net
might be better?
0: https://stackoverflow.com/questions/11670581/why-is-gnu-source-defined-by-default-and-how-to-turn-it-off
Cc: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Stanislav Fomichev <sdf@xxxxxxxxxxx>
---
tools/testing/selftests/bpf/Makefile | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index dd49c1d23a60..81d4757ecd4c 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -713,7 +713,7 @@ $(OUTPUT)/xdp_features: xdp_features.c $(OUTPUT)/network_helpers.o $(OUTPUT)/xdp
# Make sure we are able to include and link libbpf against c++.
$(OUTPUT)/test_cpp: test_cpp.cpp $(OUTPUT)/test_core_extern.skel.h $(BPFOBJ)
$(call msg,CXX,,$@)
- $(Q)$(CXX) $(CFLAGS) $(filter %.a %.o %.cpp,$^) $(LDLIBS) -o $@
+ $(Q)$(CXX) $(subst -D_GNU_SOURCE=,,$(CFLAGS)) $(filter %.a %.o %.cpp,$^) $(LDLIBS) -o $@
# Benchmark runner
$(OUTPUT)/bench_%.o: benchs/bench_%.c bench.h $(BPFOBJ)
--
2.45.2
