rustc-ap-rustc_span 722.0.0

Automatically published version of the package `rustc_span` in the rust-lang/rust repository from commit c9c1f8be3fda5b58520c579451d3f5e20736ec90 The publishing script for this crate lives at: https://github.com/alexcrichton/rustc-auto-publish

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 [`Symbol`]s, 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`]. ## Note This API is completely unstable and subject to change.