libmsgsl-dev - 4.0.0-2+deb12u1 main

The Guideline Support Library (GSL) contains functions and types that are
suggested for use by the C++ Core Guidelines maintained by the Standard C++
Foundation. This package contains Microsoft's implementation of GSL.
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The library includes types like span, string_span, owner<> and others.
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The entire implementation is provided inline in the headers under the gsl
directory. The implementation generally assumes a platform that implements
C++14 support.