Glossary

There are many core types that are used throughout this compiler. Here is a non-exhaustive list of them and their use.

Contexts

• SessionCtx (scx)

  Holds information needed for the whole compiler session. Things such as options, diagnostics, debug output.

• DiagnosticCtx (dcx)

  Contains all the diagnostic accumulation and emission related code.

• TyCtx (tcx)

  Holds information needed for type inference, type check and their results.

IDs

• session::Symbol

  Created when lexing files. It is an index to interned identifiers and strings.

• session::Span and session::BytePos

  Used extensively throughout the different intermediate representations to show good diagnostics to the user.

• ast::NodeId

  Created during the parsing step.

• resolve::DefId

  Created during the collection step.

• hir::NodeId

  Created during the lowering step.

  • hir::ExprId: they wrap normal NodeId but ensure that they point to an expression.

TyKinds

• hir::TyKind

  Holds the item definition of a type.

• ty::TyKind<InferKind, RefKind>

  Holds the concrete definition of a type.

  • ty::EarlyItemTy (ty::TyKind<NoInfer, DefId>)

  • ty::InferTy (ty::TyKind<Infer, NoRef>)

    same but keeps an extra field to store type variables in the inference step

  • ty::LateTy (ty::TyKind<NoInfer, NoRef>)