[quuxplusone]

The reason I'd want "frozen-size vector" is to replace pairs of data members of the form `T* foos; size_t foos_len;` without paying another 8 bytes to store a useless capacity that's never going to change.

But I don't think that makes such a container worth adding to the STL. So far, it hasn't even been worth writing in our own code. But that's the reason I've thought about writing it.

[uecker]

This is how I designed my vector in C. Note it is still not frozen as you can use realloc just fine (even with good performance) and/or external tracking of the capacity in tight loops.

https://uecker.codeberg.page/2025-07-20.html

I probably will still add a version with capacity, because people may insist on it, but personally I like the one without much more so far.