[huhtenberg]

> It’s very hard to write correct C code which does IO and supports multithreading

This is just a random unsubstantiated statement. There's nothing particularly "hard" about writing IO libraries that is language-specific. Multithreaded or not.

[Const-me]

When you do IO and multithreading, functions often need to acquire and release stuff: mutexes or other locks, resources, locales. Even more so in videogames, e.g. OpenGL code often calls glMapBuffer / glUnmapBuffer many thousand times each frame.

The hard part is making sure you release stuff every time you acquire stuff, exactly once. C++ RAII makes it almost trivially simple, but standard C has nothing comparable. When you only targeting gcc and clang can use __attribute__(cleanup) in C, it helps but still it’s more limited and more error prone compared to destructors.

[abcd_f]

> The * hard part * is making sure you release stuff every time, exactly once.

Oy vey... you can't be serious. That's rudimentary basics of using any API.

[Const-me]

It’s easy enough to correctly use a small API in a small program. It doesn’t matter at all for short-living apps which clean up their resources by exiting the process.

There’re also other programs in wide use, which need to reliably work for hours, sometimes weeks. Some of them have huge amount of code they built from, written by many people over many years. Combine that with large enough APIs (some peripheral devices have hundreds of writeable registers of state; or D3D11 exposes huge amount of very complicated state, only limited by VRAM amount which is measured in gigabytes) and it’s very easy to make bugs in such programs.

Leaks of memory, handles, sockets, and many other resource types e.g. GPU ones. Deadlocks caused by locked mutexes, or threads which exit but forgot to release something they needed to release. Unwanted changes to global or thread state, both internal to the process and external (locales, formatting options, console colors, process and thread priorities, current directory, environment variables, CPU registers like FPU flags and interrupt masks, GPU render states) caused by some code changing stuff but not reverting the changes back. Unwanted state changes of custom peripheral devices, due to the same reason.

C++ RAII is not a silver bullet, but it does help a lot for all these things.

[abcd_f]

It's easy enough to implement correct API usage semantics in a program of any size.

If you need to rely on RAII in order not to screw things up, then it's an issue with the coding style or the application design. That's what needs fixing. Not the language choice. You got it backwards.

[Const-me]

It’s a hard problem, and language + runtime support helps. That’s why C++ has RAII, C# has IDisposable / using, Java has try-with, python has enter / exit / with, golang has defer, and so on. The only reason C has nothing comparable, it’s almost 50 years old now.

The problem is only tangentially related to API semantics. The problem is mutating state. The state is not necessarily managed by an API, for instance CPU registers aren’t, you modify them directly. Same with other global state like I/O formatting options and locales, these things are just global variables.