feat(collection): add label(collection) documentation to lib.rs

src/lib.rs

@@ -48,6 +48,7 @@
 //!   - [... handler options](#-handler-options)
 //!   - [... dynamic diagnostics](#-dynamic-diagnostics)
 //!   - [... syntax highlighting](#-syntax-highlighting)
+//!   - [... collection of labels](#-collection-of-labels)
 //! - [Acknowledgements](#acknowledgements)
 //! - [License](#license)
 //!
@@ -672,6 +673,57 @@
 //! [`with_syntax_highlighting`](MietteHandlerOpts::with_syntax_highlighting)
 //! method. See the [`highlighters`] module docs for more details.
 //!
+//! ### ... collection of labels
+//!
+//! When the number of labels is unknown, you can use a collection of `SourceSpan`
+//! (or any type convertible into `SourceSpan`). For this, add the `collection`
+//! parameter to `label` and use any type than can be iterated over for the field.
+//!
+//! ```rust,ignore
+//! #[derive(Debug, Diagnostic, Error)]
+//! #[error("oops!")]
+//! struct MyError {
+//!     #[label("main issue")]
+//!     primary_span: SourceSpan,
+//!
+//!     #[label(collection, "related to this")]
+//!     other_spans: Vec<Range<usize>>,
+//! }
+//!
+//! let report: miette::Report = MyError {
+//!     primary_span: (6, 9).into(),
+//!     other_spans: vec![19..26, 30..41],
+//! }.into();
+//!
+//! println!("{:?}", report.with_source_code("About something or another or yet another ...".to_string()));
+//! ```
+//!
+//! A collection can also be of `LabeledSpan` if you want to have different text
+//! for different labels. Labels with no text will use the one from the `label`
+//! attribute
+//!
+//! ```rust,ignore
+//! #[derive(Debug, Diagnostic, Error)]
+//! #[error("oops!")]
+//! struct MyError {
+//!     #[label("main issue")]
+//!     primary_span: SourceSpan,
+//!
+//!     #[label(collection, "related to this")]
+//!     other_spans: Vec<LabeledSpan>, // LabeledSpan
+//! }
+//!
+//! let report: miette::Report = MyError {
+//!     primary_span: (6, 9).into(),
+//!     other_spans: vec![
+//!         LabeledSpan::new(None, 19, 7), // Use default text `related to this`
+//!         LabeledSpan::new(Some("and also this".to_string()), 30, 11), // Use specific text
+//!     ],
+//! }.into();
+//!
+//! println!("{:?}", report.with_source_code("About something or another or yet another ...".to_string()));
+//! ```
+//!
 //! ## MSRV
 //!
 //! This crate requires rustc 1.70.0 or later.