I'm aware of the restrict keyword, though its usage is not typical. It enables an optimization that fortran has by default, that was my point.

And yes, I already said that packages like blas have had massive amounts of work put into them and have lasting power.

Fortran's primary competitive advantage over C and C++ is that it's a conceptually simpler language that's easier for humans to use safely and effectively for numerical computing tasks.

It's not just being tied to BLAS and friends. Fortran lives on in academia, for example, because academics don't necessarily want to put a lot of effort into chasing wild pointers or grokking the standard template library.

For my part, I'm watching LFortran with interest because, when I run up against limitations on what I can do with numpy, I'd much rather turn to Fortran than C, C++, or Rust if at all possible, because Fortran would let me get the job done in less time, and the code would likely be quite a bit more readable.

Note that while BLAS and friends aren't getting rewritten in C, there is an effort underway to write replacements in Julia. The basic reason is that metaprogramming and better optimization frameworks are making it possible to write these at a higher level where you basically specify a cost model, and generate an optimal method based on that. The big advantage is that this works for more than just standard matrix multiplies. The same framework can give you complex matrices, Integer and boolean matrices, matrices with different algebras (eg max-plus).

Except "modern" C does not prevent one to misuse restrict and doing so is UB.