[MacPorts] #68444: protobuf3-cpp: build error in dependents: unknown type name 'max_align_t'

[MacPorts]

#68444: protobuf3-cpp: build error in dependents: unknown type name 'max_align_t'
--------------------+---------------------------
 Reporter:  jmroot  |      Owner:  mascguy
     Type:  defect  |     Status:  assigned
 Priority:  Normal  |  Milestone:
Component:  ports   |    Version:
 Keywords:          |       Port:  protobuf3-cpp
--------------------+---------------------------
 Dependents can fail to build when using some toolchain versions, see for
 example py311-onnx:
 https://build.macports.org/builders/ports-10.9_x86_64-builder/builds/249207/steps
 /install-port/logs/stdio

 {{{
 In file included from /opt/local/var/macports/build
 /_opt_bblocal_var_buildworker_ports_build_ports_python_py-
 onnx/py311-onnx/work/onnx-1.14.1/.setuptools-cmake-build/onnx/onnx-
 data.pb.cc:4:
 In file included from /opt/local/var/macports/build
 /_opt_bblocal_var_buildworker_ports_build_ports_python_py-
 onnx/py311-onnx/work/onnx-1.14.1/.setuptools-cmake-build/onnx/onnx-
 data.pb.h:24:
 In file included from /opt/local/include/google/protobuf/arena.h:52:
 /opt/local/include/google/protobuf/arena_impl.h:62:34: error: unknown type
 name 'max_align_t'; did you mean 'std::max_align_t'?
 enum { kCacheAlignment = alignof(max_align_t) };  // do the best we can
                                  ^
 /Library/Developer/CommandLineTools/usr/bin/../include/c++/v1/cstddef:55:21:
 note: 'std::max_align_t' declared here
 typedef long double max_align_t;
                     ^
 }}}

 Explicitly specifying the std namespace here would be more correct anyway,
 as `max_align_t` in the global namespace is really a C thing not C++.

-- 
Ticket URL: <https://trac.macports.org/ticket/68444>
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