Experimental Physics and
Industrial Control System

Michael Davidsaver via Tech-talk <tech-talk at aps.anl.gov> · Mon, 4 Apr 2022 14:54:45 -0700

        Thank you in advance and also for the good responses that have allowed us to move forward.

The short answer is that you should build all of the C++ parts of Base
with the same compiler version and arguments.  Including "-std=*".

https://github.com/epics-base/pvDataCPP/blob/f3911d583139ac5969df6a992c424788e41d9634/src/misc/pv/sharedPtr.h#L62-L86

On 4/4/22 13:20, Francisco Ramos via Tech-talk wrote:

Hello Community,

     I am writing to see if you could help us with the following problem we have. After making a merge between an old version and a new one (our c++ code) that now uses EPICS 7 (7.0.6.2-DEV), we get a compilation error in the linking process, that is, the library compiles correctly but when we try to compile the examples we get the error "libgiapi-glue-cc. so: *undefined reference to `epics::pvDatabase::PVDatabase::addRecord*(std::shared_ptr<epics::pvDatabase::PVRecord> const&)'"".

      Analysing the built library (libgiapi-glue-cc.so.0.16) to see the symbols defined, we have used the nm tool. We can see that the addRecord function requires the *std::shared::ptr parameter* (it must be defined in the libpvDatabase.so.4.6.1 library). The output of the nm command is copied below.
  nm --format sysv libgiapi-glue-cc.so.0.16 | c++filt | grep addR
*epics::pvDatabase::PVDatabase::addRecord(std::shared_ptr<epics::pvDatabase::PVRecord>* const&)| | | U | NOTYPE| | |*UND*

      Now, if we analyze the EPICS library *libpvDatabase.so.4.6.1*, we get that the "addRecord" function requires the parameter std::tr1::shared_ptr instead of std::shared_ptr. The output of the nm command is copied below.
*epics::pvDatabase::PVDatabase::addRecord(std::tr1::shared_ptr<epics::pvDatabase::PVRecord> const&)*| |000000000004c120| T | FUNC|0000000000000370| | |.text

     If we analyze the source code, we can see that the PVImageRecordPtr type has been defined with std::tr1::shared_ptr. Below you can se the code extract or in the following link(https://github.com/framos-gemini/giapi-glue-cc/blob/peterMerge/src/data/PVImageAgent.h <https://github.com/framos-gemini/giapi-glue-cc/blob/peterMerge/src/data/PVImageAgent.h>, line 136 and 250)

    /class PVImageRecord;
    //      typedef std::tr1::shared_ptr<PVImageRecord> PVImageRecordPtr;
    //      PVImageRecordPtr pvImageRecord;/

      Next, the PVImageRecord class inherits from the epics::pvDatabase::PVRecord class, which defines the create method. Below is a small fragment of the code: (https://github.com/framos-gemini/giapi-glue-cc/blob/peterMerge/src/data/PVImageAgent.cpp <https://github.com/framos-gemini/giapi-glue-cc/blob/peterMerge/src/data/PVImageAgent.cpp>).

    /  class PVImageRecord: public epics::pvDatabase::PVRecord {
       public:
           POINTER_DEFINITIONS(PVImageRecord);
           static PVImageRecordPtr create(std::string const & recordName, LoggerPtr lg)/

       In the same PVImageAgent.cpp file, line 606, is where the record is introduced. As you can see, the *addRecord function is being called* with the *std::tr1::shared_ptr *type (PVImageRecordPtr pvImageRecord) instead of *std::shared_ptr.* Therefore, it is strange what is happening. Any suggestions?

        Thank you in advance and also for the good responses that have allowed us to move forward.

Regards,

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System