Documentation

Generating Documentation with cargo doc

The cargo doc command invokes rustdoc on your package (and optionally its dependencies) to compile all /// and //! documentation comments into a static, offline-searchable HTML website inside target/doc/.

Source Files (`src/lib.rs`, `Cargo.toml`)
             |
             v  `cargo doc --no-deps --open`
     [ rustdoc compiler ]
             |
             v
target/doc/<crate_name>/index.html  (Static HTML + JS Search Index)

Essential cargo doc Flags

Command Behavior
cargo doc Generates HTML docs for the current package and all of its dependencies in target/doc/.
cargo doc --no-deps Generates HTML docs only for the current package (or workspace), skipping dependency docs for much faster builds.
cargo doc --open Generates docs and automatically opens the crate's root index.html in your default web browser.
cargo doc --document-private-items Includes private functions, private struct fields, and internal modules in the generated HTML (useful for internal application architecture docs).
cargo doc --workspace --no-deps Builds unified documentation for all crates in a Cargo workspace.
cargo doc --all-features Enables all Cargo feature flags so feature-gated modules and items are included in the docs. 
# Fast local iteration workflow: build only local crate docs and open in browser
cargo doc --no-deps --open

Controlling rustdoc Behavior with Crate Attributes

Crate-level #![doc(...)] attributes at the top of src/lib.rs customize how rustdoc renders your crate and enforces documentation coverage:

Crate Attribute Effect
#![warn(missing_docs)] Emits a compiler warning on any public item (pub struct, pub fn, pub enum variant, pub field) that lacks a doc comment.
#![deny(rustdoc::broken_intra_doc_links)] Fails cargo doc if any [Item] intra-doc link cannot be resolved.
#![deny(rustdoc::bare_urls)] Warns/errors on unlinked raw https://... URLs not wrapped in <https://...> or [text](url).
#[doc(hidden)] Hides a pub item (such as an internal macro helper) from generated HTML docs while keeping it publicly exported for macros.
#[doc(alias = "search_term")] Adds alternative search keywords (such as operator symbols "+" or terminology from other languages) to rustdoc's search bar.
#[doc(inline)] / #[doc(no_inline)] Controls whether a pub use re-export is rendered inline on the current page or listed under a "Re-exports" link. 
#![warn(missing_docs)]
#![deny(rustdoc::broken_intra_doc_links)]

//! Core string joining utilities.

/// Joins two strings with a `/` separator.
///
/// Users searching for `"concat"` or `"path_join"` in `cargo doc` will find this function.
#[doc(alias = "concat")]
#[doc(alias = "path_join")]
pub fn join_slash(left: &str, right: &str) -> String {
    format!("{}/{}", left.trim_end_matches('/'), right.trim_start_matches('/'))
}

/// Internal helper exported only for declarative macros; hidden from `cargo doc`.
#[doc(hidden)]
pub fn __internal_macro_helper() -> &'static str {
    "internal"
}

fn main() {
    println!("Joined: {}", join_slash("/api/v1/", "/users"));
}

Joined: /api/v1/users