errcheck VS too-many-lists

In our codebase I noticed a few cases where people ignored errors returned from functions by assigning them to _, ie result, _ := foo(). The errcheck linter doesn't seem to catch this, does anyone know of a linter that does?

And we also expect that the caller will check the error and handle it. There is a popular linter that checks it for us: errcheck.

You should be using golangci-lint, because all serious Go programmers should. golangci-lint contains errcheck, which will detect if you overwrite an error without having done something with it in the meantime. I consider this one of the most important linters (this doesn't just detect things that may sorta kinda someday turn into bugs, this quite likely is a bug RIGHT NOW), and it helps you have the confidence you can overwrite errors as you go and don't need to keep allocating new ones.

Run golangci-lint over your code if you haven't already and pay special attention to errcheck's output.

errcheck has a flag for that ;)

https://github.com/kisielk/errcheck, which is in most of the combined linter packages by default.

We'll agree to disagree about unused imports; imports have can side-effects.

I prefer functions returning errors over throwing exceptions. Whether it's Go's errors or ML-style options/results, they're both better than exceptions. I cannot remember the last time I had a bug from not checking an error in Go. There's also errcheck which I use as part of my linting that will catch unchecked errors, such that I cannot even commit the code.

> Go compiler raise an error if a variable (error) goes unused

It doesn't though. It's perfectly valid to not use the return value of a function that only returns an error, for instance.

There are static error checking tools you can use like https://github.com/kisielk/errcheck to work around this, but most people don't use them.

I've run into a lack of Go error checking many times. Many times it's just the trivial case, where the compiler doesn't warn about not checking the result of an error-returning function.

But often it'll be subtler, and the result of Go's API design. One example is its file writing API, which requires you to close the file and check its error to be correct. Many times people will just `defer file.Close()`, but that isn't good enough - you're ignoring the error there.

Worse still is e.g: writing to a file through a bufio.Writer. To be correct, you need to remember to flush the writer, check that error, then close the file and check that error. There's no type-level support to make sure you do that.

I'd be really happy with that! Building the functionality of errcheck[1] and ineffassign[2] into the compiler — or at the very least, into govet — would go a long way to allay my worries with Go.

I think the reason they don't do this is that it's a slight (albeit a very tiny one) against Go's philosophy of errors being values, just like any other. While the `error` type is standard and used throughout Go source code, it still just has a simple three-line definition[3] and is not treated as a special case anywhere else; there is nothing stopping you from returning your own error type if you wish. A third-party linter could simply check for the `error` type specifically, but the first-party tools should not, and there's nothing like Rust's `#[must_use]` attribute that could be used instead. I respect Go's philosophy, but I feel like pragmatism must win in this case.

[1]: https://github.com/kisielk/errcheck

You seem to have a preset opinion, and I'm not sure you are interested in re-evaluating it. So this is not written to change your mind.

I've developed production code in C, C++, Rust, and several other languages. And while like pretty much everything, there are situations where it's not a good fit, I find that the solutions tend to be the most robust and require the least post release debugging in Rust. That's my personal experience. It's not hard data. And yes occasionally it's annoying to please the compiler, and if there were no trait constraints or borrow rules, those instances would be easier. But way more often in my experience the compiler complained because my initial solution had problems I didn't realize before. So for me, these situations have been about going from building it the way I wanted to -> compiler tells me I didn't consider an edge case -> changing the implementation and or design to account for that edge case. Also using one example, where is Rust is notoriously hard and or un-ergonomic to use, and dismissing the entire language seems premature to me. For those that insist on learning Rust by implementing a linked list there is https://rust-unofficial.github.io/too-many-lists/.

Advent of Code was okay until I encounterd a problem that required a graph, tree or linked list to solve, where I hit a wall. Most coding exercises are similar--those requiring arrays and hashmaps and sets are okay, but complex data structures are a PITA. (There is an online course dedicated to linked lists in Rust but I couldn't grok it either). IMO you should simply skip problems that you can't solve with your current knowledge level and move on.

I feel obligated to point to the original cannon literature: https://rust-unofficial.github.io/too-many-lists/

I started learning Rust and like how the compiler is fussy about things. My plan was to implement the data structures I knew, but I got stuck at the singly linked list's remove() method. I've read the book as well, but I have no clue how to simplify this further:

My impression from the article is that Zig provides several different hashtables and not all of them are broken in this way.

This reminds me of Aria's comment in her Rust tutorial https://rust-unofficial.github.io/too-many-lists/ about failing to kill LinkedList. One philosophy (and the one Rust chose) for a stdlib is that this is only where things should live when they're so commonly needed that essentially everybody needs them either directly or to talk about. So, HashTable is needed by so much otherwise unrelated software that qualifies, BloomFilter, while it's real useful for some people, not so much. Aria cleaned out Rust's set of standard library containers before Rust 1.0, trying to keep only those most people would need. LinkedList isn't a good general purpose data structure, but, it was too popular and Aria was not able to remove it.

Having multiple hash tables feels like a win (they're optimized for different purposes) but may cost too much in terms of the necessary testing to ensure they all hit the quality you want.

> Cyclic references can be dealt with runtime safety checks too - like Rc and Weak.

Indeed. Starting out with code sprinkled with Rc, Weak, RefCell, etc is perfectly fine and performance will probably not be worse than in any other safe languages. And if you do this, Rust is pretty close to those languages in ease of use for what are otherwise complex topics in Rust.

A good reference for different approaches is Learn Rust With Entirely Too Many Linked Lists https://rust-unofficial.github.io/too-many-lists/

Second, once you've finished something introductory like The Book, read Learning Rust With Entirely Too Many Linked Lists. It really helped me to understand what ownership and borrowing actually mean in practical terms. If you don't mind paying for learning materials, a lot of people recommend Programming Rust, Second Edition by Blandy, Orendorff, and Tindall as either a complement, follow-up, or alternative to The Book.

Learning Rust With Entirely Too Many Linked Lists which highlights a lot of the differences with how you need to structure your code in Rust compared to other languages.