Cereal is embedding its own version of RapidJSON. This embedded version has been patched to use custom include path (cereal/external/rapidjson/ instead of rapidjson/) and macros ( CEREAL_RAPIDJSON_ instead of RAPIDJSON_).
This prevents a conflict at compile time with another RapidJSON used by the client.
As a result, if a client uses both Cereal and a different version of RapidJSON (or compiles it with an option such as RAPIDJSON_HAS_STDSTRING) then (s)he ends up with an ODR violation 😢
That's what happened to me: my application works well on Windows 11 and crashes on Windows 10... ODR magic!
I see several options here, that could be combined:
modify CEREAL_RAPIDJSON_NAMESPACEto something like cereal::rapidjson or cereal_rapidjson to really isolate the vendored version of RapidJSON from another one that could be used by the client
update cmake scripts to allow Cereal to use an external RapidJSON library provided by the user. This is generally done by exposing a cmake option such as USE_EXTERNAL_RAPIDJSON.
I selected the second option. And at the same time, I removed the (forced) dependency on RapidXML because I don't want to embed dependencies I don"t need (I am in a strongly regulated context).
Note that, in my case, all of that is done by a Conan recipe that patches and cleans up Cereal code before packaging it.
Hello,
Cereal is embedding its own version of RapidJSON. This embedded version has been patched to use custom include path (
cereal/external/rapidjson/instead ofrapidjson/) and macros (CEREAL_RAPIDJSON_instead ofRAPIDJSON_).This prevents a conflict at compile time with another RapidJSON used by the client.
But! The RapidJSON symbols are still defined in the same original namespace
rapidjson: https://github.com/USCiLab/cereal/blob/v1.3.2/include/cereal/external/rapidjson/rapidjson.h#L118As a result, if a client uses both Cereal and a different version of RapidJSON (or compiles it with an option such as
RAPIDJSON_HAS_STDSTRING) then (s)he ends up with an ODR violation 😢That's what happened to me: my application works well on Windows 11 and crashes on Windows 10... ODR magic!
I see several options here, that could be combined:
CEREAL_RAPIDJSON_NAMESPACEto something likecereal::rapidjsonorcereal_rapidjsonto really isolate the vendored version of RapidJSON from another one that could be used by the clientUSE_EXTERNAL_RAPIDJSON.I selected the second option. And at the same time, I removed the (forced) dependency on RapidXML because I don't want to embed dependencies I don"t need (I am in a strongly regulated context).
Note that, in my case, all of that is done by a Conan recipe that patches and cleans up Cereal code before packaging it.
What do you think is the best option?