> Does it make sense to still invest time to learn C++ when Rust exists?
Yes. The overwhelming majority of industry is using C/C++.
Rust is still very much niche when compared to the overall market.
Additionally, (Someone can correct me if this is wrong) IIRC, mozilla, was initially one of the biggest proponents of rust, but still just uses rust in a supplementary role. C++ still powers the heavy lifting.
Mozilla is not “one of the biggest proponents of Rust” anymore, in that other, larger entities are now as well. Rust is at the center of many products, large and small.
That doesn’t mean that C and C++ aren’t also large, even larger, but this has been changing for years and only shows signs of accelerating, not slowing down.
The size difference is like Sutter Buttes versus Mahalangur Himal, so unless it's accelerating at the speed of light, C++ will be dwarfing rust's usage for many years to come.
This is the umpteenth time large tech companies have sponsored C++'s successor. Go was famously created to eventually supplant C++ at Google (or more specifically, solve the issue of long build times). Over a decade later, C++ is very much still in heavy usage at Google.
If I were a bettin' man (or if I were trying to increase my general employment odds), and the choices were between Rust or C++, I would pick C++.
That being said, if I were in a comfortable financial position, wanted to scratch a nerd itch, and have fun programming again, I would absolutely pick Rust over C++.
I certainly do not disagree that C and C++ will be in general usage for a long time, if not forever. However, because the industry is still growing, the proportions change, even as the total number grows in size. C and C++ do not have to die, or even shrink, to become a smaller part of the overall pie, and Rust does not need them to outright die in order to grow and thrive.
I agree with you that this is not the first time languages have tried to encroach on the last bastions of the spaces where C and C++ have not yet been ousted as the default choice, but Rust is actually gaining traction in production use-cases in those spaces, unlike many of those languages.
It really depends on your career goals and whether you're doing greenfield or maintenance coding. If you want to be part of the "new generation" of tech, learn Rust. If you want job security, dont care about doing anything glamorous or exciting, and don't mind a long learning journey, go with C++. It will always be around and it's hard enough to learn that you won't have as much competition.
Only things written in Rust I know are rewrites of decades old C applications or rewrites of js tooling. What "new generation" of games, browsers, editors, CAD applications, etc. are written in Rust? Is Rust used in aerospace, automotive, healthcare, instrumentation or finance industries? What is glamorous in Rust that hasn't been done in other languages?
I think rewrites can be as "glamorous" as greenfield, because you get to use a modern language and toolset. yes you have some drudgery tacked on, which is likely having to wade through legacy C code, but having a perfect set of working requirements (do what the old app does!) more than makes up for it.
It is difficult to answer this question because there are so many answers, and they're so broad. I will try to give some partial answers.
> games
Some indie games, a new AAA studio has been working on a game for a while (Embark, their first game is still in C++ but they are building the foundations for the next ones, which takes time), at least one AAA studio known to use it for tooling (Treyarch). The first time I personally gave a talk at a AAA studio about Rust was 2019, though I don't believe that studio is using it for anything I am aware of.
> browsers
Firefox is about 12% Rust by volume, but is also only 41% C and C++, so it's about a quarter of the relevant systems level code. Chromium has Rust in the tree, but only libraries right now, they don't write new code yet except wrappers. Brave has an adblock component in Rust.
> CAD applications
Not aware of movement here.
> aerospace,
Very early days, some small projects, nothing massive yet.
> automotive,
This one is gearing up massively: a rust compiler was just qualified for the relevant safety standards to be used in automotive, several large manufacturers have had job openings open mentioning Rust. It certainly hasn't taken over the world yet but there's a lot of actual movement in this space.
> healthcare,
Not aware of specific things here.
> instrumentation
I don't know what the "instrumentation industry" is.
> finance
Some players are using some things, but as a very proprietary industry, not a lot of specifics are known. I have given an internal talk at a big hedge fund a few years back, unsure if they're doing anything in production just yet.
There are other big successes that aren't covered by these industries; Shopify adding a JIT to Ruby, Cloudflare's heavy use of Rust (which means that a significant chunk of internet traffic passes through Rust code), AWS's heavy use of Rust (the core of products like Lambda and S3 are in Rust these days), Apple using it for network services appparently, Meta keeping their monorepo in a version control system written in Rust, and it being an official language to use on projects there, Google using Rust for significant components in Android, Windows having added Rust code already, with more to come, Rust becoming the next language used in the Linux kernel... the stories are endless at this point.
Yes. The overwhelming majority of industry is using C/C++.
Rust is still very much niche when compared to the overall market.
Additionally, (Someone can correct me if this is wrong) IIRC, mozilla, was initially one of the biggest proponents of rust, but still just uses rust in a supplementary role. C++ still powers the heavy lifting.