On 4/12/21 9:32 PM, Andrii Nakryiko wrote:
On Sat, Apr 10, 2021 at 9:49 AM Yonghong Song <yhs@xxxxxx> wrote:
With clang compiler:
make -j60 LLVM=1 LLVM_IAS=1 <=== compile kernel
make -j60 -C tools/testing/selftests/bpf LLVM=1 LLVM_IAS=1
the test_cpp build failed due to the failure:
warning: treating 'c-header' input as 'c++-header' when in C++ mode, this behavior is deprecated [-Wdeprecated]
clang-13: warning: cannot specify -o when generating multiple output files
test_cpp compilation flag looks like:
clang++ -g -Og -rdynamic -Wall -I<...> ... \
-Dbpf_prog_load=bpf_prog_test_load -Dbpf_load_program=bpf_test_load_program \
test_cpp.cpp <...>/test_core_extern.skel.h <...>/libbpf.a <...>/test_stub.o \
-lcap -lelf -lz -lrt -lpthread -o <...>/test_cpp
The clang++ compiler complains the header file in the command line.
Let us remove the header file from the command line which is not intended
any way, and this fixed the problem.
Signed-off-by: Yonghong Song <yhs@xxxxxx>
---
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 6448c626498f..bbd61cc3889b 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -481,7 +481,7 @@ $(OUTPUT)/test_verifier: test_verifier.c verifier/tests.h $(BPFOBJ) | $(OUTPUT)
# 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) $^ $(LDLIBS) -o $@
+ $(Q)$(CXX) $(CFLAGS) test_cpp.cpp $(BPFOBJ) $(LDLIBS) -o $@
see what we do for other binaries:
$(filter %.a %.o %.c,$^)
It's more generic. Add %.cpp, of course.
Okay, although I will remove %.c.
[yhs@devbig003.ftw2 ~/tmp/tmp2]$ clang++ -c t.c
clang-13: warning: treating 'c' input as 'c++' when in C++ mode, this
behavior is deprecated [-Wdeprecated]
[yhs@devbig003.ftw2 ~/tmp/tmp2]$
clang++ will warn if trying to compile .c file.
g++ 8.4.1 doesn't warn. Not sure about latest g++. But it is not
a good practice to compile .c files with c++ compiler any way.
# Benchmark runner
$(OUTPUT)/bench_%.o: benchs/bench_%.c bench.h
--
2.30.2
