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Fix -Wundefined-inline error when using SharedCtor() or SharedDtor() #8532
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acozzette
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georgthegreat:fix-undefined-inline
Apr 28, 2021
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Fix -Wundefined-inline error when using SharedCtor() or SharedDtor() #8532
acozzette
merged 1 commit into
protocolbuffers:master
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georgthegreat:fix-undefined-inline
Apr 28, 2021
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NB: I do not know if there is any procedure behind pregenerated .pb.h files update for well known types. |
Thanks @georgthegreat |
georgthegreat
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Jul 19, 2021
Apparentle, protocolbuffers#8532 was incorrect if applied to 3.17.x branch. 3.17.x changed code generation to mark SharedCtor and SharedDtor as inline in .pb.cc. It looks like we have a compile-time undefined behavior in C++ now. As cppreferences [says](https://en.cppreference.com/w/cpp/language/inline): _The definition of an inline function or variable (since C++17) must be reachable in the translation unit where it is accessed (not necessarily before the point of access). _ As protobuf allows custom plugins to generate custom code, there is no limitation on where SharedCtor couble be possible referenced from. In our case we have SharedCtor invoked from corresponding `.pb.h` code, thus triggering: ``` ld: error: undefined symbol: package::Message::SharedCtor()` >>> referenced by file.pb.h:$$$$ ``` If this patch is not applicable, I can take a look into changing the code generation, but doing this will be harder then removing _inline_.
georgthegreat
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Jul 20, 2021
Apparently, protocolbuffers#8532 was incorrect if applied to 3.17.x branch. 3.17.x changed code generation to mark `SharedCtor()` and `SharedDtor()` as inline in .pb.cc. It looks like we have a compile-time undefined behavior in C++ now. As cppreference.com [says](https://en.cppreference.com/w/cpp/language/inline): _The definition of an inline function <...> must be reachable in the translation unit where it is accessed (not necessarily before the point of access)._ As protobuf allows custom plugins to generate custom code, there is no limitation on where SharedCtor couble be possible referenced from. In our case we have SharedCtor invoked from corresponding `.pb.h` code, thus triggering: ``` ld: error: undefined symbol: package::Message::SharedCtor()` >>> referenced by file.pb.h:$$$$ ``` If this patch is not applicable, I can take a look into changing the code generation, but doing this will be harder then removing _inline_.
acozzette
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Jul 29, 2021
* Fix undefined symbol error around SharedCtor() Apparently, #8532 was incorrect if applied to 3.17.x branch. 3.17.x changed code generation to mark `SharedCtor()` and `SharedDtor()` as inline in .pb.cc. It looks like we have a compile-time undefined behavior in C++ now. As cppreference.com [says](https://en.cppreference.com/w/cpp/language/inline): _The definition of an inline function <...> must be reachable in the translation unit where it is accessed (not necessarily before the point of access)._ As protobuf allows custom plugins to generate custom code, there is no limitation on where SharedCtor couble be possible referenced from. In our case we have SharedCtor invoked from corresponding `.pb.h` code, thus triggering: ``` ld: error: undefined symbol: package::Message::SharedCtor()` >>> referenced by file.pb.h:$$$$ ``` If this patch is not applicable, I can take a look into changing the code generation, but doing this will be harder then removing _inline_. * Regenerate checked-in generated .pb.cc files
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protoc marks SharedCtor and SharedDtor as inline in
.h
file being generated, but does not define them in this header.An attempt to use these symbols causes compiler to issue
-Wundefined-inline
warning / error if-Werror
is enabled.