Expand description

Implementation of lint checking.

The lint checking is mostly consolidated into one pass which runs after all other analyses. Throughout compilation, lint warnings can be added via the add_lint method on the Session structure. This requires a span and an ID of the node that the lint is being added to. The lint isn’t actually emitted at that time because it is unknown what the actual lint level at that location is.

To actually emit lint warnings/errors, a separate pass is used. A context keeps track of the current state of all lint levels. Upon entering a node of the ast which can modify the lint settings, the previous lint state is pushed onto a stack and the ast is then recursed upon. As the ast is traversed, this keeps track of the current lint level for all lint attributes.




Early lints work on different nodes - either on the crate root, or on freshly loaded modules. This trait generalizes over those nodes.