OrthoConfig: Undocumented Structs & Documentation Fixes

Hey guys, let's dive into a bit of a head-scratcher we've encountered with the OrthoConfig derive macro. You know how we love our clean, well-documented Rust code? Well, sometimes external tools can throw a wrench in that, and that's exactly what's happening here. The core issue is that OrthoConfig, when it does its magic, generates these extra structs – think of them as siblings to the main struct you've defined. The kicker? These generated siblings are completely undocumented, and we can't even slap a #[doc] or #[expect(missing_docs)] directly onto them. This means we're often forced into using a crate-level #![expect(missing_docs)] suppression, which, let's be honest, isn't ideal, especially if you're running a tight ship with lints that demand specific, narrow suppressions. It's like getting a gift you can't quite unwrap properly – frustrating!

The Nitty-Gritty: Undocumented Siblings

So, what's the deal with these sibling structs? When you use #[derive(OrthoConfig)] on a struct, say PgEnvCfg, it also churns out related types. A prime example is something like PgEnvCfgBuilder. The problem is, these generated types just appear out there in the module scope, not nested nicely within the original struct. Because they're generated on the fly by the macro, they don't automatically inherit any documentation, and more importantly, we can't add our own #[doc = "..."] comments or even specific #[expect(missing_docs)] attributes to just these generated structs. This lack of direct control is the root of our documentation headache. It’s a bit like a chef preparing a fantastic meal but forgetting to add the garnish – it's still good, but it's missing that final polish. We want our code to be as clear and self-explanatory as possible, and these undocumented bits really get in the way of that goal. It makes code reviews a little tougher and can leave newcomers to the codebase scratching their heads.

Why This Matters for Your Project

This isn't just about aesthetics, folks. Clear documentation is crucial for maintainability and collaboration. When these generated structs are left undocumented, it creates friction. Anyone reading the code might wonder what PgEnvCfgBuilder is for, how it relates to PgEnvCfg, and how they should use it. Without explicit documentation, they're left to infer or dig through the macro's generated code, which is a significant time sink and a potential source of errors. For teams that adhere to strict linting rules, this becomes a blocker. Many modern lint configurations aim for highly specific suppressions – you turn off a warning for a particular line or block of code, not for the entire crate. A crate-level suppression like #![expect(missing_docs)] is a blunt instrument; it silences all missing documentation warnings across the entire project, potentially masking other genuine documentation issues. This is precisely why we need a more granular solution. We want to be able to say, "Okay, this specific generated struct is undocumented, and here's why," rather than resorting to a blanket silence that could hide other problems.

A Real-World Example of the Pain

Let's paint a clearer picture with the example you've provided. Imagine you've got this clean, simple struct:

#[derive(OrthoConfig)]
pub struct PgEnvCfg {
    pub port: Option<u16>,
}

This is perfectly fine, right? You've defined your configuration for a PostgreSQL environment, specifying an optional port. Now, OrthoConfig kicks in, and behind the scenes, it's generating code. What pops out into your module is something like this:

// Generated by OrthoConfig, undocumented!
pub struct PgEnvCfgBuilder { 
    // ... fields and methods for building PgEnvCfg ... 
}

See the problem? This PgEnvCfgBuilder struct is now part of your public API (or at least accessible within the module), but it has no documentation. You can't add /// Builder for PgEnvCfg above it because it's macro-generated. You also can't add #[expect(missing_docs)] directly to this struct definition to tell the linter, "Hey, I know this is missing docs, and it's okay." It’s like having a helpful assistant who speaks in riddles – they're trying to help, but their communication is unclear. This undocumented nature forces our hand. The common, albeit imperfect, workaround is to add this at the very top of your lib.rs or main.rs file:

#![expect(missing_docs, reason = "OrthoConfig derive generates undocumented sibling structs")]

While this does silence the warning, it feels like a compromise. The reason is good for human readers, but it doesn't solve the fundamental issue of the generated code lacking proper documentation hooks. It's a band-aid on a problem that could potentially be solved more elegantly.

The Impact on Code Quality Metrics

This situation can also skew your code quality metrics. Tools that analyze documentation coverage might flag your crate as having lower documentation quality than it actually does because they can't account for the macro-generated parts. If you're striving for 100% documentation coverage or using metrics as a guide for code improvement, this becomes a persistent annoyance. It's a small thing, but in the grand scheme of maintaining a high-quality codebase, every detail counts. We want our tools to accurately reflect the health and completeness of our code, and when external factors like derive macros interfere with that, it requires attention. The goal is a transparent and informative development process, and these undocumented generated types disrupt that transparency.

What We're Aiming For: The Ideal Scenario

Okay, so we've identified the problem and the current workaround. What would be the perfect solution here? What are we hoping for to make this whole OrthoConfig experience smoother?

There are a few paths we could take, and honestly, any of them would be a massive improvement over the current state of affairs. The main goal is to ensure that these generated sibling structs are either documented automatically or that we have a clear way to add documentation to them.

Option 1: Automatic Documentation Generation

This is perhaps the most elegant solution. If the OrthoConfig macro could be smart enough to generate basic doc comments for the sibling structs it creates, that would be fantastic. For instance, when it generates PgEnvCfgBuilder, it could automatically add /// Builder for PgEnvCfg`` right above it. This is the kind of intelligent generation that makes macros so powerful. It would mean that these structs would ship with sensible, albeit minimal, documentation out of the box. No extra effort required from the user, and the missing_docs lint would be satisfied automatically. This aligns perfectly with the principle of least surprise – the generated code just works and is documented.

Option 2: User-Defined Documentation via Attributes

Alternatively, if automatic generation isn't feasible or desirable for some reason, providing a way for users to specify the documentation would be the next best thing. This could be achieved through a custom attribute. Imagine being able to write something like this:

#[derive(OrthoConfig)]
#[ortho_config(builder_docs = "Custom documentation for the builder")]
pub struct PgEnvCfg {
    pub port: Option<u16>,
}

Or perhaps a more general attribute that targets generated types. This gives developers fine-grained control. They can provide the exact documentation they deem necessary for their specific use case. This approach respects the flexibility of Rust's attribute system and allows for customization where needed, while still addressing the core problem of missing documentation and satisfying linters.

Option 3: Clear Documentation of the Limitation

Finally, if neither of the above is possible, the next best step is transparency. The creators of OrthoConfig could simply document this limitation clearly in the macro's own documentation. A section explaining that sibling structs are generated without documentation and that users will need to use crate-level suppressions would be incredibly helpful. This manages expectations. Developers would know upfront that this is a known issue and how to handle it, rather than stumbling upon it and getting frustrated. It’s about clear communication and setting the right expectations for users of the library. Knowing is half the battle, as they say!

The Current Workaround: Crate-Level Suppression

As we've touched upon, the immediate fix for the missing_docs warnings caused by these undocumented sibling structs is to use a crate-level suppression attribute. This looks like:

#![expect(missing_docs, reason = "OrthoConfig derive generates undocumented sibling structs")]

This line, typically placed at the top of your lib.rs or main.rs, tells the Rust compiler's linting system to ignore any warnings about missing documentation throughout the entire crate. The addition of the reason field is crucial. It provides context for why this suppression is in place, making the code more understandable for anyone reviewing it later. It explicitly states that the issue stems from the OrthoConfig derive macro generating undocumented types that cannot be individually documented.

Why This Isn't a Perfect Solution

While this workaround gets the job done in terms of silencing compiler warnings, it's far from ideal. The primary drawback is its lack of specificity. A crate-level suppression turns off all missing_docs warnings. This means that if there are other parts of your code that genuinely should have documentation but don't, those warnings will also be silenced. You lose the ability to catch those legitimate documentation gaps because the noise from the macro-generated structs drowns them out. This can lead to a false sense of security regarding your overall documentation quality. It's like using a master key that opens every door – convenient, but it also means you might miss seeing a room that's supposed to be locked for a reason.

Furthermore, for teams that enforce strict linting policies, particularly those aiming for minimal and targeted suppressions, a crate-level blanket suppression can be a point of contention. It deviates from best practices, which encourage suppressions to be as localized as possible (i.e., applied directly to the code that needs it). This makes it harder to maintain a high standard of code quality and can require extra justification during code reviews. It's a necessary evil for now, but definitely something we'd like to see improved upon in future versions of OrthoConfig.

Moving Forward: Seeking a Better Way

Ultimately, the goal is to have our derive macros play nicely with documentation standards and linting rules. The current situation with OrthoConfig isn't a dealbreaker, but it's an imperfection that detracts from the otherwise excellent developer experience it provides. Whether through automatic doc generation, attribute-based customization, or simply clearer documentation of the limitation, we're hopeful that the OrthoConfig maintainers (or the community) will address this. Having generated code that is just as well-documented as hand-written code is the dream. It ensures consistency, improves maintainability, and keeps our linting tools happy. So, let's keep an eye on OrthoConfig's development – a small change there could make a big difference in how we document our Rust projects. Cheers!