Crate rustc_span

source ·
Expand description

Source positions and related helper functions.

Important concepts in this module include:

  • the span, represented by SpanData and related types;
  • source code as represented by a SourceMap; and
  • interned strings, represented by Symbols, with some common symbols available statically in the sym module.

Unlike most compilers, the span contains not only the position in the source code, but also various other metadata, such as the edition and macro hygiene. This metadata is stored in SyntaxContext and ExpnData.


This API is completely unstable and subject to change.


pub use hygiene::DesugaringKind;
pub use hygiene::ExpnKind;
pub use hygiene::MacroKind;
pub use hygiene::ExpnData;
pub use hygiene::ExpnHash;
pub use hygiene::ExpnId;
pub use hygiene::LocalExpnId;
pub use hygiene::SyntaxContext;
pub use symbol::sym;
pub use symbol::Symbol;


Machinery for hygienic macros.
Levenshtein distances.
Types for tracking pieces of source code within a crate.
An “interner” is a data structure that associates values with usize tags and allows bidirectional lookup; i.e., given a value, one can easily find the type, and vice versa.


impl_pos 🔒


A byte offset.
A character offset.
A single debugger visualizer file.
Range inside of a Span used for diagnostics when we only have access to relative positions.
A source code location used for error reporting.
Identifies an offset of a multi-byte character in a SourceFile.
Identifies an offset of a character that was normalized away from SourceFile.
Per-session global variables: this struct is stored in thread-local storage in such a way that it is accessible without any kind of handle to all threads within the compilation session, but is not accessible outside the session.
A single source in the SourceMap.
The source file lines in difference list form. This matches the form used within metadata, which saves space by exploiting the fact that the lines list is sorted and individual lines are usually not that long.
The hash of the on-disk source file used for debug info.
A compressed span.
Represents a span.


The state of the lazy external source loading mechanism of a SourceFile.
Differentiates between real files and common virtual files.
Identifies an offset of a non-narrow character in a SourceFile.


Dummy span, both position and length are zero, syntax context is zero as well.



Requirements for a StableHashingContext to be used in this crate.


Replaces \r\n with \n in-place in src.
Normalizes the source code and records the normalizations.
remove_bom 🔒
Removes UTF-8 BOM, if any.
Calls the provided closure, using the provided SourceMap to format any spans that are debug-printed during the closure’s execution.

Type Definitions