package/cc-tool: link with libatomic when needed

Detecting the boost program_options library is broken:

checking for the Boost program_options library... no
configure: error: cannot find the flags to link with Boost program_options

config.log shows the reason, libatomic is missing:

conftest.o: In function `boost::detail::sp_counted_base::release()':
conftest.cpp:(.text._ZN5boost6detail15sp_counted_base7releaseEv[_ZN5boost6detail15sp_counted_base7releaseEv]+0xc):
undefined reference to `__atomic_fetch_sub_4'
conftest.cpp:(.text._ZN5boost6detail15sp_counted_base7releaseEv[_ZN5boost6detail15sp_counted_base7releaseEv]+0x38):
undefined reference to `__atomic_fetch_sub_4'
/home/buildroot/br4/output/host/sparc-buildroot-linux-uclibc/sysroot/usr/lib/libboost_program_options.so:
undefined reference to `__atomic_fetch_add_4'

Please note that using LIBS=-latomic is not enough, although it fixes the configure check the bug reoccurs when linking cc-tool:

CXXLD cc-tool
src/application/cc_flasher.o: In function `boost::detail::sp_counted_base::weak_release()':
cc_flasher.cpp:(.text._ZN5boost6detail15sp_counted_base12weak_releaseEv[_ZN5boost6detail15sp_counted_base12weak_releaseEv]+0xc):
undefined reference to `__atomic_fetch_sub_4'

We need to add -latomic to CXXFLAGS to both fix configure and linking.

Fixes
http://autobuild.buildroot.net/results/596/596f97364bb2c7598b0646da8160939356f0d2c6/

---
 package/cc-tool/cc-tool.mk | 4 ++++
 1 file changed, 4 insertions(+)

index b9209ced3..37ac57e49 100644
@@ -23,4 +23,8 @@ ifeq ($(BR2_STATIC_LIBS),y)
 CC_TOOL_CONF_ENV += LIBS="-lpthread"
 endif
 
+ifeq ($(BR2_TOOLCHAIN_HAS_LIBATOMIC),y)
+CC_TOOL_CONF_ENV += CXXFLAGS="$(TARGET_CXXFLAGS) -latomic"
+endif
+
 $(eval $(autotools-package))

2.11.0

Hello,

To be honest, this is not the ideal solution. Indeed, it's not cc-tool itself that needs libatomic, but the libboost_program_options library. So the dynamic linking situation would better be solved by having libboost_program_options linked against libatomic. However, this wouldn't solve the static linking situation. And since cc-tool doesn't use pkg-config to detect boost, we're pretty much out of luck.

So, I've applied your patch, even if not ideal.

Thanks!

Thomas

Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com