Rust Alternatives

rust reviews and mentions

• Fish (shell) porting to Rust from C++
  9 projects | news.ycombinator.com | 30 Jan 2023

  Let's make it a bit more concrete with an actual example of submitted code.

  Here's a recent patch I wrote "Improve E0308: suggest user meant to use byte literal, w/ tests and fix" which adds a suggestion for Rust's diagnostic when you write for example '*' the literal char, Unicode U+002A but it needed a single byte and that's not what a char is. My code suggests adding the prefix b, so writing b'*' here, meaning the ASCII code for that symbol 0x2A which is a single byte ::

  https://github.com/tialaramex/rust/commit/130d02b62e65c5f2a4...

  I wrote that code but I don't understand the internals of how self.tcx.sess().source_map().span_to_snippet(span) works. Not my problem, we're in the diagnostics code so even if this is perhaps slightly slower than optimal it doesn't matter because a human will need to read this output and act on it - E0308 is a type mismatch, the program does not compile as written.

  Does my reviewer know? Maybe, I didn't ask them, but they don't really need to, it's clearly fine here to call this stuff, there won't be a nasty surprise "Oh, make sure you restore the FQ5 when setting Z due to calling sess() in this code" because that's not how Rust works whereas in a language like C++ of course such traps may exist.

  Now there is some risk I made a logic mistake, but, I wrote tests for this of course, unlike with subtle memory safety bugs, logic bugs are often caught by proper testing. My tests her are somewhat superficial, I check 'X' and '#' which should both cause the suggestion, and I check '€' which should not, but I think they cover the cases the compiler will really see here.