-Qunused-arguments lost for libbitcoinconsensus #7961

OS X:

g++ -dynamiclib  -o .libs/libbitcoinconsensus.0.dylib  crypto/.libs/libbitcoinconsensus_la-hmac_sha256.o crypto/.libs/libbitcoinconsensus_la-hmac_sha512.o crypto/.libs/libbitcoinconsensus_la-ripemd160.o crypto/.libs/libbitcoinconsensus_la-sha1.o crypto/.libs/libbitcoinconsensus_la-sha256.o crypto/.libs/libbitcoinconsensus_la-sha512.o .libs/libbitcoinconsensus_la-arith_uint256.o consensus/.libs/libbitcoinconsensus_la-merkle.o .libs/libbitcoinconsensus_la-hash.o primitives/.libs/libbitcoinconsensus_la-block.o primitives/.libs/libbitcoinconsensus_la-transaction.o .libs/libbitcoinconsensus_la-pubkey.o script/.libs/libbitcoinconsensus_la-bitcoinconsensus.o script/.libs/libbitcoinconsensus_la-interpreter.o script/.libs/libbitcoinconsensus_la-script.o script/.libs/libbitcoinconsensus_la-script_error.o .libs/libbitcoinconsensus_la-uint256.o .libs/libbitcoinconsensus_la-utilstrencodings.o   secp256k1/.libs/libsecp256k1.a -L/opt/local/lib -L/opt/local/lib/db48  -fstack-protector-all -g -O2 -pthread -Wl,-headerpad_max_install_names -Wl,-dead_strip   -pthread -install_name  /usr/local/lib/libbitcoinconsensus.0.dylib -compatibility_version 1 -current_version 1.0 -Wl,-single_module
clang: warning: argument unused during compilation: '-pthread'
clang: warning: argument unused during compilation: '-pthread'

-Qunused-arguments got lost for libbitcoinconsensus somehow... Adding it to this cmdline silenced the warning again. Other link phases are OK and this is the only one emitting this warning.

configure output contains:

checking whether Clang needs flag to prevent "argument unused" warning when linking with -pthread... -Qunused-arguments

@theuni Any idea why it is missing?

@paveljanik the CPPFLAGS aren't applied on the link-line, so this makes sense.

The issue here is actually that it's trying to use -pthread for libbitcoinconsensus, so the warning is actually legitimate. I think there's a new upstream macro that probably fixes that, I'll give that a shot.

I've tried with dropping in the latest ax_pthread serial (23, we currently use 22), and the output still seems to be the same.

Relevant discussion https://savannah.gnu.org/patch/?8186

Is this still an issue?

Just did:

./autogen.sh
./configure
make check -j5

with macOS 10.13.6 at (4a3e8c5. Didn't see any unused argument warnings. Upstream pthread is also serial 24, which is just doc changes from our 23. I think we can close this for now.