Visual Studio 2015 provides fairly 'complete' support of C++11. Currently we are already adding extra code to maintain older gcc-4.x for Linux; that one even predates vs2015. Some customers on Windows may still be operating on code built using Visual Studio 2015 (vc140) compiler, and may be targeting Windows 7.x and above. Our current CI loops are only testing Visual Studio 2017 (C++14) and Visual Studio 2019 (C++19), both by default targeting Windows 10.x and above. And we do not really cover Visual Studio 2015 (C++11) yet.

Recommendation is, as a minimum, add Visual Studio 2015 + CMake build using choco install microsoft-build-tools --version=14.0.25420.1 , to make sure that the API and SDK all compiles with an older compiler. And that our backports of nostd:: classes are all operational. There could be issues discovered that'd need fixing.

This is a blocker for adoption of OpenTelemetry SDK by a few larger codebase customers.