Unavoidable EventLogger Deprecated Warning

[ln-hei]

Describe your environment

• Library: opentelemetry-cpp
• Version: 1.21.0
• Component: OTLP Logger
• Compiler: Microsoft Visual C++
• Build Environment: Using strict compiler flags that treat warnings as errors.

Steps to reproduce

• Set up a project using opentelemetry-cpp v1.21.0.
• Create a C++ source file that includes the logger provider header, following the official example code.

#include "opentelemetry/logs/provider.h"

int main()
{
  // The warning is triggered by the include directive alone.
  return 0;
}

• Compile the code.

What is the expected behavior?

The code should compile cleanly without any warnings, as no deprecated functionality is being explicitly used.

What is the actual behavior?

Including the <opentelemetry/logs/provider.h> header file results in a compiler warning, even if no deprecated symbols are used in the code.

The specific warning is:

warning C4996: 'opentelemetry::v1::logs::EventLogger::~EventLogger': was declared deprecated

Additional context

This issue is problematic in environments where compiler warnings are treated as errors, causing the build to fail. A temporary workaround is to use macros to suppress the C4996 warning around the include directive, but a permanent fix is needed.

The full error log is:

C:\Program Files\Microsoft Visual Studio\2022\Professional\VC\Tools\MSVC\14.42.34433\include\memory(1190,9): warning C4996: 'opentelemetry::v1::logs::EventLogger::~EventLogger': was declared deprecated
1>(compiling source file '[...]/OpenTelemetryLogger.cpp')
1>    C:\Program Files\Microsoft Visual Studio\2022\Professional\VC\Tools\MSVC\14.42.34433\include\memory(1190,9):
1>    the template instantiation context (the oldest one first) is
1>        [...]\opentelemetry-cpp-1.21.0\msvc\include\opentelemetry\logs\noop.h(126,34):
1>        see reference to class template instantiation 'opentelemetry::v1::nostd::shared_ptr<opentelemetry::v1::logs::EventLogger>' being compiled
1>        [...]\opentelemetry-cpp-1.21.0\msvc\include\opentelemetry\nostd\shared_ptr.h(84,3):
1>        while compiling class template member function 'opentelemetry::v1::nostd::shared_ptr<opentelemetry::v1::logs::EventLogger>::shared_ptr(opentelemetry::v1::logs::EventLogger *)'
1>            [...]\opentelemetry-cpp-1.21.0\msvc\include\opentelemetry\logs\noop.h(115,75):
1>            see the first reference to 'opentelemetry::v1::nostd::shared_ptr<opentelemetry::v1::logs::EventLogger>::shared_ptr' in 'opentelemetry::v1::logs::NoopEventLoggerProvider::NoopEventLoggerProvider'
1>        [...]\opentelemetry-cpp-1.21.0\msvc\include\opentelemetry\nostd\shared_ptr.h(86,28):
1>        see reference to function template instantiation 'std::shared_ptr<T>::shared_ptr<opentelemetry::v1::logs::EventLogger,0>(_Ux *)' being compiled
1>        with
1>        [
1>            T=opentelemetry::v1::logs::EventLogger,
1>            _Ux=opentelemetry::v1::logs::EventLogger
1>        ]
1>        C:\Program Files\Microsoft Visual Studio\2022\Professional\VC\Tools\MSVC\14.42.34433\include\memory(1584,61):
1>        see reference to class template instantiation 'std::_Ref_count<opentelemetry::v1::logs::EventLogger>' being compiled
1>        C:\Program Files\Microsoft Visual Studio\2022\Professional\VC\Tools\MSVC\14.42.34433\include\memory(1189,10):
1>        while compiling class template member function 'void std::_Ref_count<opentelemetry::v1::logs::EventLogger>::_Destroy(void) noexcept'
1>C:\Program Files\Microsoft Visual Studio\2022\Professional\VC\Tools\MSVC\14.42.34433\include\memory(1525,9): warning C4996: 'opentelemetry::v1::logs::EventLogger::~EventLogger': was declared deprecated
1>(compiling source file '[...]/OpenTelemetryLogger.cpp')
1>    C:\Program Files\Microsoft Visual Studio\2022\Professional\VC\Tools\MSVC\14.42.34433\include\memory(1525,9):
1>    the template instantiation context (the oldest one first) is
1>        C:\Program Files\Microsoft Visual Studio\2022\Professional\VC\Tools\MSVC\14.42.34433\include\memory(1583,35):
1>        see reference to class template instantiation 'std::_Temporary_owner<opentelemetry::v1::logs::EventLogger>' being compiled
1>        C:\Program Files\Microsoft Visual Studio\2022\Professional\VC\Tools\MSVC\14.42.34433\include\memory(1524,6):
1>        while compiling class template member function 'std::_Temporary_owner<opentelemetry::v1::logs::EventLogger>::~_Temporary_owner(void)'
1>            C:\Program Files\Microsoft Visual Studio\2022\Professional\VC\Tools\MSVC\14.42.34433\include\memory(1583,41):
1>            see the first reference to 'std::_Temporary_owner<opentelemetry::v1::logs::EventLogger>::~_Temporary_owner' in 'std::shared_ptr<T>::shared_ptr'
1>        with
1>        [
1>            T=opentelemetry::v1::logs::EventLogger
1>        ]
1>            [...]\opentelemetry-cpp-1.21.0\msvc\include\opentelemetry\nostd\shared_ptr.h(86,28):
1>            see the first reference to 'std::shared_ptr<T>::shared_ptr' in 'opentelemetry::v1::nostd::shared_ptr<opentelemetry::v1::logs::EventLogger>::shared_ptr'
1>        with
1>        [
1>            T=opentelemetry::v1::logs::EventLogger
1>        ]
1>            [...]\opentelemetry-cpp-1.21.0\msvc\include\opentelemetry\logs\noop.h(115,75):
1>            see the first reference to 'opentelemetry::v1::nostd::shared_ptr<opentelemetry::v1::logs::EventLogger>::shared_ptr' in 'opentelemetry::v1::logs::NoopEventLoggerProvider::NoopEventLoggerProvider'
1>C:\Program Files\Microsoft Visual Studio\2022\Professional\VC\Tools\MSVC\14.42.34433\include\memory(1190,9): warning C4996: 'opentelemetry::v1::logs::EventLoggerProvider::~EventLoggerProvider': was declared deprecated
1>(compiling source file '[...]/OpenTelemetryLogger.cpp')
1>    C:\Program Files\Microsoft Visual Studio\2022\Professional\VC\Tools\MSVC\14.42.34433\include\memory(1190,9):
1>    the template instantiation context (the oldest one first) is
1>        [...]\opentelemetry-cpp-1.21.0\msvc\include\opentelemetry\logs\provider.h(58,3):
1>        see reference to class template instantiation 'opentelemetry::v1::nostd::shared_ptr<opentelemetry::v1::logs::EventLoggerProvider>' being compiled
1>        [...]\opentelemetry-cpp-1.21.0\msvc\include\opentelemetry\nostd\shared_ptr.h(84,3):
1>        while compiling class template member function 'opentelemetry::v1::nostd::shared_ptr<opentelemetry::v1::logs::EventLoggerProvider>::shared_ptr(opentelemetry::v1::logs::EventLoggerProvider *)'
1>            [...]\opentelemetry-cpp-1.21.0\msvc\include\opentelemetry\logs\provider.h(87,59):
1>            see the first reference to 'opentelemetry::v1::nostd::shared_ptr<opentelemetry::v1::logs::EventLoggerProvider>::shared_ptr' in 'opentelemetry::v1::logs::Provider::GetEventProvider'
1>        [...]\opentelemetry-cpp-1.21.0\msvc\include\opentelemetry\nostd\shared_ptr.h(86,28):
1>        see reference to function template instantiation 'std::shared_ptr<T>::shared_ptr<opentelemetry::v1::logs::EventLoggerProvider,0>(_Ux *)' being compiled
1>        with
1>        [
1>            T=opentelemetry::v1::logs::EventLoggerProvider,
1>            _Ux=opentelemetry::v1::logs::EventLoggerProvider
1>        ]
1>        C:\Program Files\Microsoft Visual Studio\2022\Professional\VC\Tools\MSVC\14.42.34433\include\memory(1584,61):
1>        see reference to class template instantiation 'std::_Ref_count<opentelemetry::v1::logs::EventLoggerProvider>' being compiled
1>        C:\Program Files\Microsoft Visual Studio\2022\Professional\VC\Tools\MSVC\14.42.34433\include\memory(1189,10):
1>        while compiling class template member function 'void std::_Ref_count<opentelemetry::v1::logs::EventLoggerProvider>::_Destroy(void) noexcept'
1>C:\Program Files\Microsoft Visual Studio\2022\Professional\VC\Tools\MSVC\14.42.34433\include\memory(1525,9): warning C4996: 'opentelemetry::v1::logs::EventLoggerProvider::~EventLoggerProvider': was declared deprecated
1>(compiling source file '[...]/OpenTelemetryLogger.cpp')
1>    C:\Program Files\Microsoft Visual Studio\2022\Professional\VC\Tools\MSVC\14.42.34433\include\memory(1525,9):
1>    the template instantiation context (the oldest one first) is
1>        C:\Program Files\Microsoft Visual Studio\2022\Professional\VC\Tools\MSVC\14.42.34433\include\memory(1583,35):
1>        see reference to class template instantiation 'std::_Temporary_owner<opentelemetry::v1::logs::EventLoggerProvider>' being compiled
1>        C:\Program Files\Microsoft Visual Studio\2022\Professional\VC\Tools\MSVC\14.42.34433\include\memory(1524,6):
1>        while compiling class template member function 'std::_Temporary_owner<opentelemetry::v1::logs::EventLoggerProvider>::~_Temporary_owner(void)'
1>            C:\Program Files\Microsoft Visual Studio\2022\Professional\VC\Tools\MSVC\14.42.34433\include\memory(1583,41):
1>            see the first reference to 'std::_Temporary_owner<opentelemetry::v1::logs::EventLoggerProvider>::~_Temporary_owner' in 'std::shared_ptr<T>::shared_ptr'
1>        with
1>        [
1>            T=opentelemetry::v1::logs::EventLoggerProvider
1>        ]
1>            [...]\opentelemetry-cpp-1.21.0\msvc\include\opentelemetry\nostd\shared_ptr.h(86,28):
1>            see the first reference to 'std::shared_ptr<T>::shared_ptr' in 'opentelemetry::v1::nostd::shared_ptr<opentelemetry::v1::logs::EventLoggerProvider>::shared_ptr'
1>        with
1>        [
1>            T=opentelemetry::v1::logs::EventLoggerProvider
1>        ]
1>            [...]\opentelemetry-cpp-1.21.0\msvc\include\opentelemetry\logs\provider.h(87,59):
1>            see the first reference to 'opentelemetry::v1::nostd::shared_ptr<opentelemetry::v1::logs::EventLoggerProvider>::shared_ptr' in 'opentelemetry::v1::logs::Provider::GetEventProvider'

[lalitb]

That’s a bit unfortunate, because many users only care about LoggerProvider and never touch the deprecated EventLoggerProvider, yet they still get a warning just by including the header.

We can fix this by adding scoped diagnostic suppression inside provider.h, only around the deprecated member definitions and their helpers. That way, simply including the header won’t trigger the warning, but actual calls to the deprecated APIs will still produce it (which should be fine).

Once ABI v2 becomes the default, these deprecated members will be excluded entirely, and the warning will go away without any suppression.