errcheck VS golangci-lint

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

One of the checkers in golangci-lint does this. I forget which one.

golangci-lint rolls up lot of linters and checkers into a single binary.

There is a config file too.

https://github.com/golangci/golangci-lint

golangci-lint is an amazing open-source tool for CI in Go projects. Basically, it's an aggregator and a Go linters runner that makes life easier for developers. It includes all the well-known liners by default but also provides an easy way to integrate new ones.

Fun fact: We actually use a code linter via golangci-linter to catch misspellings in code/comments using client9/misspell.

The "standard linter" in Go is https://golangci-lint.run/ , which includes [1] the absolutely-vital errcheck which will do that for you.

For an Advent of Code challenge you may want to turn off a lot of other things, since the linter is broadly tuned for production, public code by default and you're creating burner code and don't care whether or not you have godoc comments for your functions, for instance. But I suggest using golangci-lint rather than errcheck directly because there's some other things you may find useful, like ineffassign, exportloopref, etc.

[1]: https://golangci-lint.run/usage/linters/

golangci-lint recently integrated go-check-sumtype. I recommend using golangci-lint as a pre-commit hook, but if you're in a real hurry you can replace "go build" with a shell script that runs go-check-sumtype instead. This is probably better than a weird hack, not that you're saying that the weird hack is a good idea anyhow.

Golangci-lint is a tool for checking Go code quality, finding issues, bugs, and style problems. It helps keep the code clean and maintainable.

This is such an infuriating problem. I'm convinced I'm using Go wrong, because I simply can't understand how this doesn't make it a toy language. Why the $expletive am I wasting 20-30 and more minutes per week of my life looking for the source of an error!?

Have you seen https://github.com/tomarrell/wrapcheck? It's a linter than does a fairly good job of warning when an error originates from an external package but hasn't been wrapped in your codebase to make it unique or stacktraced. It comes with https://github.com/golangci/golangci-lint and can even be made part of your in-editor LSP diagnostics.

But still, it's not perfect. And so I remain convinced that I'm misunderstanding something fundamental about the language because not being able to consistently find the source of an error is such an egregious failing for a programming language.