Build issue on macOS 14.0

[xanadu6291]

Issue description

I can't build libzmq on macOS 14.0

Environment

• libzmq version (commit hash if unreleased): Ver.4.3.5
• OS: macOS 14.0

Minimal test code / Steps to reproduce the issue

1. I configure the latest stable release (Ver.4.3.5) of libzmq as follows:
   $ ./configure --prefix=${TARGET} --enable-static --disable-shared --without-documentation

2. Then type make

What's the actual result? (include assertion message & call stack if applicable)

I get the following error:
src/proxy.cpp:502:26: error: suggest braces around initialization of subobject [-Werror,-Wmissing-braces]
stats_proxy stats = {0};
^
{}
src/proxy.cpp:502:26: error: suggest braces around initialization of subobject [-Werror,-Wmissing-braces]
stats_proxy stats = {0};
^
{}
2 errors generated.
make[1]: *** [src/libzmq_la-proxy.lo] Error 1
make: *** [all-recursive] Error 1

What's the expected result?

Build correctly.

[xanadu6291]

I thought that the compiler claims to add braces. Which means:

stats_proxy stats = {0};
to
stats_proxy stats = {{0}};

But failed with same error. Then I tried to add one more braces. ( Yes, I don't understand C++ at all):

stats_proxy stats = {{0}};
to
stats_proxy stats = {{{0}}};

Then compiled zeromq successfully.

Is it OK to add two braces into stats_proxy stats?

[devnullpointer]

Same issue here building 4.3.5 on Ubuntu 22.04LTS.

CXX src/libzmq_la-poller_base.lo
CXX src/libzmq_la-polling_util.lo
CXX src/libzmq_la-pollset.lo
CXX src/libzmq_la-precompiled.lo
CXX src/libzmq_la-proxy.lo
src/proxy.cpp:502:26: error: suggest braces around initialization of subobject [-Werror,-Wmissing-braces]
stats_proxy stats = {0};
^
{}
src/proxy.cpp:502:26: error: suggest braces around initialization of subobject [-Werror,-Wmissing-braces]
stats_proxy stats = {0};
^
{}
2 errors generated.
make[1]: *** [Makefile:5869: src/libzmq_la-proxy.lo] Error 1

[devnullpointer]

Tried 4.3.4 on Ubuntu 22.04 LTS and it builds fine. Seems like an issue with 4.3.5