Pipeline

Current front-end compiler pipeline looks like the following:

Input is an input, Bold is a step, Italic is an artefact.

-> is used by, => produces

1. Source code -> Lexing & Parsing => AST

   Understand the form of the user source code.

2. AST -> Item Collection, Item Resolution => NameEnvironment, ResolutionMap

   Go through each item and associate names of items to ast::NodeIds.

   It makes sense to collect before AST Lowering because

   • this information can be used during the lowering for path resolution
   • it is used to provide diagnostics to user code, AST is closer to what the user wrote

3. AST, ResolutionMap -> AST Lowering => HIR

   We lower the AST to a flat structure (soon™) that is the HIR.

   HIR is much more usable in the context of a compiler.

4. HIR -> Type Collection => TypeEnvironment

   Go through each item and compute their ty::EarlyItemTy.

   Once, the collection phase is done, these are immediately resolved to ty::LateTys.

5. HIR, NameEnvironment, TypeEnvironment -> Inference (per function) => InferResult

6. HIR, InferResult -> Code Generation => Object