I've only have a pretty basic understanding of how it works, but I thought the checks didn't rely on the compiler. They're special templates that fail when their conditions aren't met
And when I say it didn't take off - I mean that I haven't come across a single large project that has take up using the GSL. Hope I'm wrong - maybe I just haven't looked in the right place?
No, GSL is a kind of stop-gap solution, until standard catches on.
For example std::string_view and ongoing design on std::array_view are based on gsl::span. The gsl::byte is also no longer needed on C++17 thanks to std::byte as yet another example.
The GSL asserts are there until code contracts[0] get into the standard.
The magical types like gsl::owner allow clang-tidy and VC++ checkers to apply a Rust-like memory tracking usage.
As for not taking off, being initially a Microsoft proposal, it is surely used by Office and Windows teams, specially given they already use SDL (Security Definition Language) macros as well.
And when I say it didn't take off - I mean that I haven't come across a single large project that has take up using the GSL. Hope I'm wrong - maybe I just haven't looked in the right place?