alt Hacker News> C++ containers are designed for average demands. If you need something more specific, you can always use an alternative implementation.
As someone who has been programming exclusively in C/C++ for a long time -- the biggest selling point for these languages in 2026 is exactly being suited to doing something specific, not generic.
> Allocations aren't implicit
std::map<int,int> m;
m[1] = 42; // implicit alloc
auto m2 = m; // implicit too
Theory and practice. Making everything const correct is too painful in practice, often impossible. It's a trap for bean counters that can't focus on getting some actual useful work done. I'm being harsh to my own past self here. Counter question: why include allocation mechanics with some existing data that never gets changed? Why should we have to add much more boilerplate to get the simpler thing?
> m[1] = 42; // implicit alloc
operator[] of associative containers is mutating and may allocate. It's mentioned in the documentation. And there is no operator[] overloading for const instances, so that you can't trigger an allocation by just reading elements from it.
> auto m2 = m; // implicit too
Taking a copy requires making an allocation. Do you expect some other behavior in such case?
> Making everything const correct is too painful in practice, often impossible
Maybe you are dealing with some legacy codebase (from 90s)? I have worked with multiple codebases in past 10 years or so and keeping things which shouldn't be mutated const wasn't a problem at all. All the code was written using such approach.
> why include allocation mechanics with some existing data that never gets changed
I don't think I fully understand this question. What never gets changed? In your example you are mutating a container and taking a copy of it (which can be changed later).