It seems that way, which is a big disincentive to use Rust at all.
It seems that way, which is a big disincentive to use Rust at all.
* doesn't have subslice patterns * has `Error::description`, which has since been deprecated * doesn't have x86 CPU feature detection * lacks fix for unsound typecasts between integers and floats * lacks fix for incomplete constant propagation * doesn't let you use conditionals, loops, match, $$, or || in constant fns, or cast arrays to slices in constant fns * has less-helpful error messages and backtraces * doesn't let you implement traits on arrays with lengths >32 * has worse type inference, this (valid since 1.43.0) code doesn't compile because 0.0 and &0.0 are f64s: let n: f32 = 0.0 + &0.0; * requires you to import standard libraries to use predefined numeric constants (like MAXINT or NaN) * doesn't support Control Flow Guard on Windows * doesn't generate documentation links from classpaths (you have to write relative file paths instead)
and numerous libraries being pre-stable.
For code that you're writing yourself, not having these features is mostly just a quality-of-life issue: you'll have to do things that you wouldn't have to do if you had the latest compiler. For code that you're collaborating on, having an 10-months-older compiler can be a showstopper: the code might just not compile at all, and very likely the only fix will be to uninstall your system-packaged rustc and install the version from rustup.
Contrast this with C/C++ development, where your system's pre-packaged compilers are much more likely to be sufficiently up-to-date. These languages are more mature than Rust: they change slower, and new features are adopted by programmers more gradually. For example, the Linux kernel only requires GCC 4.9 [1], which was released in 2013. Debian stable supplies GCC 8.3, which will probably be able to compile unmodified kernel source code for many years without being updated.
[1] https://www.kernel.org/doc/html/latest/process/changes.html
I just don't really see this as a problem - Rust really isn't that much of a moving target, and the benefit is there is one solution to the problem: use Rustup to manage your Rust installation.
That is significantly more robust than "use your package manager."