Cairo Annotations

The cairo-annotations crate provides tools tailored for working with annotations in the Cairo language. These annotations are part of the Sierra Debug Information format and serve to enrich the code by detailing information.

To see JSON example of the annotations, check the following file.

Features of Cairo Annotations

Structured Annotations

cairo-annotations offers a structured representation, allowing for more ergonomic manipulation of annotations. Some key features include:

• Coverage Annotations: Track locations in the Cairo code that correspond to specific Sierra statements.
• Profiler Annotations: Provide mappings from Sierra statements to fully qualified Cairo paths, detailing which functions in the Cairo code triggered them.

All annotations implement the TryFromDebugInfo trait, enabling their extraction from Sierra debug information. Here's a simple example:

let annotations = VersionedCoverageAnnotations::try_from_debug_info(sierra_debug_info).unwrap();

Coverage Annotations

Coverage annotations provide a mapping from Sierra statement indices to sources in the Cairo code that resulted in their creation. For extensive documentation, see CoverageAnnotationsV1.

Example to retrieve code location information:

use cairo_annotations::annotations::coverage::{
    CodeLocation, ColumnNumber, CoverageAnnotationsV1, LineNumber, SourceCodeLocation,
    SourceCodeSpan, SourceFileFullPath, VersionedCoverageAnnotations,
};
use cairo_annotations::annotations::TryFromDebugInfo;
use cairo_lang_sierra::program::StatementIdx;

let VersionedCoverageAnnotations::V1(annotations) =
    VersionedCoverageAnnotations::try_from_debug_info(sierra_debug_info).unwrap();

let code_locations = annotations
    .statements_code_locations
    .get(&StatementIdx(331))
    .unwrap();

assert_eq!(
    code_locations,
    &[CodeLocation(
        SourceFileFullPath("/path/to/my/file.cairo".into()),
        SourceCodeSpan {
            start: SourceCodeLocation { line: LineNumber(7), col: ColumnNumber(4) },
            end: SourceCodeLocation { line: LineNumber(7), col: ColumnNumber(4) },
        }
    )]
);

Profiler Annotations

Profiler annotations map Sierra statement indices to Cairo function paths, showing which functions led to their generation. Detailed information is available in ProfilerAnnotationsV1.

Example to get the Cairo path:

use cairo_annotations::annotations::profiler::{
    FunctionName, ProfilerAnnotationsV1, VersionedProfilerAnnotations,
};
use cairo_annotations::annotations::TryFromDebugInfo;
use cairo_lang_sierra::program::StatementIdx;

let VersionedProfilerAnnotations::V1(annotations) =
    VersionedProfilerAnnotations::try_from_debug_info(sierra_debug_info).unwrap();

let functions_names = annotations
    .statements_functions
    .get(&StatementIdx(331))
    .unwrap();

assert_eq!(
    functions_names,
    &[FunctionName("scarb_template::fib".into())]
);

Versioning

Annotations are versioned to ensure backward compatibility with different formats. The VersionedCoverageAnnotations and VersionedProfilerAnnotations enums encapsulate the different versions of the annotations. The versioning goes as V1, V2, V3, and so on, with the greatest version representing the latest version.

Integration with snforge

Annotations are particularly useful for getting information about executed code. If you are using snforge, you can leverage the --save-trace-data flag to generate trace data.

Deserialize this data using VersionedCallTrace from the cairo-annotations crate, and subsequently use map_pcs_to_sierra_statement_ids to map the trace to Sierra statement IDs.