Building protobuf3-cpp :info:build ./google/protobuf/map_field.h:332:37: error: constexpr constructor never produces a constant expression [-Winvalid-constexpr]

[dbl001 (dbl)]

OS X 10.11.6

:info:build In file included from google/protobuf/dynamic_message.cc:80:
:info:build ./google/protobuf/map_field.h:332:37: error: constexpr constructor never produces a constant expression [-Winvalid-constexpr]
:info:build   explicit PROTOBUF_MAYBE_CONSTEXPR MapFieldBase(ConstantInitialized)
:info:build                                     ^
:info:build ./google/protobuf/map_field.h:335:9: note: non-literal type 'internal::WrappedMutex' cannot be used in a constant expression
:info:build         mutex_(GOOGLE_PROTOBUF_LINKER_INITIALIZED),
:info:build         ^
:info:build 1 error generated.
:info:build make[2]: *** [google/protobuf/dynamic_message.lo] Error 1

[ryandesign (Ryan Carsten Schmidt)]

In 05a56f2d5fcf8863e261c36ecb78902f61c2854c/macports-ports (master):

protobuf3-cpp: Fix build on 10.11

Blacklist clang < 900.

Closes: #61751

[Schamschula (Marius Schamschula)]

In f714e0715c4368da1fab8dcf09e77c1a51e529fb/macports-ports (master):

py-protobuf3: Fix build on 10.11 (and below)

Closes: #62158
See: #61751

[chrstphrchvz (Christopher Chavez)]

In 88655518a01243af83b96b165157f37c9c8f0d80/macports-ports (master):

protobuf-c: fix build on macOS 10.11 and earlier

See: #61751