Comment by apaprocki

Sure, the parent was commenting more about the capability existing in Ada in contrast to C. Ada variable length local variables are basically C alloca(). The interesting part in Ada is returning variable length types from functions and having them automatically managed via the “secondary stack”, which is a fixed size buffer in embedded/constrained environments. The compiler takes care of most of the dirty work for you.

We mainly use C++, not C, and we do this with polymorphic allocators. This is our main allocator for local stack:

https://bloomberg.github.io/bde-resources/doxygen/bde_api_pr...

… or this for supplying a large external static buffer:

https://bloomberg.github.io/bde-resources/doxygen/bde_api_pr...