Struct Diagnostic 

pub struct Diagnostic { /* private fields */ }

A renderable diagnostic: a message, an optional label on the offending span, and optional help text. Built from a ParseError via ParseError::into_diagnostic.

Deliberately does not carry the source text or a display path: those are supplied separately to render_diagnostic, matching how a caller (typically a CLI reading a file) already has both on hand and shouldn’t need to clone the source into every error it produces.

Implementations

impl Diagnostic

pub fn new( message: impl Into<String>, span: Option<Span>, help: Option<String>, ) -> Self

Creates a diagnostic from a message, an optional byte-offset span into the source, and optional help text.

This is the constructor other crates use to lift their own errors into something render_diagnostic can render, without this crate exposing Diagnostic’s fields (deliberately private — see the struct’s doc comment). alba-core’s CoreError::into_diagnostic is the first such caller: CoreError already carries a message, an optional Span, and optional help in the same shape a ParseError does, so it goes through this constructor rather than duplicating Diagnostic’s internals or alba-syntax growing a dependency on alba-core’s error type.

span is None for a failure that has no place in the source to point at — a beam named on the command line that does not exist, for instance. Such a diagnostic renders as the message and its help alone: asserting a source position that is not where the mistake is misleads a reader more than showing none does.

Trait Implementations

impl Clone for Diagnostic

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Diagnostic

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Diagnostic for Diagnostic

fn help<'a>(&'a self) -> Option<Box<dyn Display + 'a>>

Additional help text related to this Diagnostic. Do you have any advice for the poor soul who’s just run into this issue?

fn labels(&self) -> Option<Box<dyn Iterator<Item = LabeledSpan> + '_>>

Labels to apply to this Diagnostic’s Diagnostic::source_code

fn code<'a>(&'a self) -> Option<Box<dyn Display + 'a>>

Unique diagnostic code that can be used to look up more information about this Diagnostic. Ideally also globally unique, and documented in the toplevel crate’s documentation for easy searching. Rust path format (foo::bar::baz) is recommended, but more classic codes like E0123 or enums will work just fine.

fn severity(&self) -> Option<Severity>

Diagnostic severity. This may be used by ReportHandlers to change the display format of this diagnostic.

fn url<'a>(&'a self) -> Option<Box<dyn Display + 'a>>

URL to visit for a more detailed explanation/help about this Diagnostic.

fn source_code(&self) -> Option<&dyn SourceCode>

Source code to apply this Diagnostic’s Diagnostic::labels to.

fn related<'a>( &'a self, ) -> Option<Box<dyn Iterator<Item = &'a dyn Diagnostic> + 'a>>

Additional related Diagnostics.

fn diagnostic_source(&self) -> Option<&dyn Diagnostic>

The cause of the error.

impl Display for Diagnostic

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Error for Diagnostic

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0:

use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.