Compiler diagnostics

parcel_core::Diagnostic and parcel_core::Code describe parse, check, and compilation failures.

Diagnostic

Field	Type	Meaning
code	Code	Machine-readable error category.
rule	Option<String>	Affected rule ID, when available.
message	String	Human-readable explanation.
help	Option<String>	What to change, when parcel can say: a suggested name, a type, or the operation that fits.
line	Option<usize>	The 1-based line of the document, when known.

impl Diagnostic {
    pub fn new(code: Code, rule: Option<&str>, message: impl Into<String>) -> Self;
    pub fn with_help(self, help: impl Into<String>) -> Self;
    pub fn at_line(self, line: usize) -> Self;
}

The constructor copies the optional rule ID and takes the message. Diagnostic implements Display and std::error::Error. Match code in tooling; message and help wording can change. In JSON, help and line are left out when absent.

parcel_core::diag::did_you_mean(word, candidates) returns the candidate closest to a likely typo, if one is close enough.

Code variants

Category	Variants
Document and placement	Document, Residency, Unsupported, Inheritance
Rule identifiers	InvalidRuleId, DuplicateRuleId
Columns and types	DuplicateExpose, UnknownColumn, BadType, ExposeTypeMismatch, UnreadableColumn, TypeMismatch
Expressions	Parse, OutsideProfile, UnknownIdentifier, UnknownField, Namespace, NonDeterministic, Untranslatable
Functions	UnknownFunction, NoMatchingOverload
Transformations	TransformTarget, DuplicateTransform
Shapes	UnknownShapeOperator, ShapeParams

ContractDoc::parse returns one diagnostic; ContractDoc::parse_all, checking and compilation return a vector so multiple problems can be reported together.