This refactors how we deal with items in hir-def lowering.
- It now lowers all of them through an "ExpressionStore" (kind of a misnomer as this point) as their so called *Signatures.
- We now uniformly lower type AST into TypeRefs before type inference.
- Likewise, this moves macro expansion out of type inference, resulting in a single place where we do non-defmap macro expansion.
- Finally, this PR removes a lot of information from ItemTree, making the DefMap a lot less likely to be recomputed and have it only depend on actual early name resolution related information (not 100% true, we still have ADT fields in there but thats a follow up removal).
In the body source map, we record each macro call with the `ExprOrPatId` it resolved to, so to lookup the `ExprId` of some node, we don't need to expand it!
We miss one place: associated type bindings aka. `impl Trait<Type(..): Send>`, but we also miss it for Fn-style parenthesizes error so I left it out for now.
A new syntax node `ast::VariantDef` has been introduced to map between the HIR node and the AST.
The files have been updated with `cargo test -p xtask`.
Signed-off-by: Prajwal S N <prajwalnadig21@gmail.com>
Specifically, when a rename of a local will change some code that refers it to refer another local, or some code that refer another local to refer to it.
We do it by introducing a dummy edit with an annotation. I'm not a fond of this approach, but I don't think LSP has a better way.
This is required to format evaluated consts, because we need trait env, and it needs the crate (currently it uses the last crate in topological order, which is wrong, the next commit will fix that).
Also fix the `needs_drop()` intrinsic.
Unions also need this information (to err if they have a drop-needing field), but this will come in a follow-up PR.
And add a new diagnostic for non-`Fn` parenthesized generic args.
Path lowering started to look like a mess, with each function carrying additional parameters for the diagnostic callback (since paths can occur both in type and in expression/pattern position, and their diagnostic handling is different) and the segment index, for the diagnostics report. So I refactored it from stateless functions on `TyLoweringContext` into stateful struct, `PathLoweringContext`, that tracks the process of lowering a path from resolution til assoc types selection.
