Module ra_ap_hir_def::nameres

This module implements import-resolution/macro expansion algorithm.

The result of this module is CrateDefMap: a data structure which contains:

• a tree of modules for the crate
• for each module, a set of items visible in the module (directly declared or imported)

Note that CrateDefMap contains fully macro expanded code.

Computing CrateDefMap can be partitioned into several logically independent “phases”. The phases are mutually recursive though, there’s no strict ordering.

Collecting RawItems

This happens in the raw module, which parses a single source file into a set of top-level items. Nested imports are desugared to flat imports in this phase. Macro calls are represented as a triple of (Path, Option, TokenTree).

Collecting Modules

This happens in the collector module. In this phase, we recursively walk tree of modules, collect raw items from submodules, populate module scopes with defined items (so, we assign item ids in this phase) and record the set of unresolved imports and macros.

While we walk tree of modules, we also record macro_rules definitions and expand calls to macro_rules defined macros.

Resolving Imports

We maintain a list of currently unresolved imports. On every iteration, we try to resolve some imports from this list. If the import is resolved, we record it, by adding an item to current module scope and, if necessary, by recursively populating glob imports.

Resolving Macros

macro_rules from the same crate use a global mutable namespace. We expand them immediately, when we collect modules.

Macros from other crates (including proc-macros) can be used with foo::bar! syntax. We handle them similarly to imports. There’s a list of unexpanded macros. On every iteration, we try to resolve each macro call path and, upon success, we run macro expansion and “collect module” phase on the result

Modules

diagnostics

Diagnostics emitted during DefMap construction.

Structs

DefMap	Contains the results of (early) name resolution.
ModuleData

Enums

ModuleOrigin
ModuleSource