So that given a `TypeRef` we will be able to trace it back to source code.
This is necessary to be able to provide diagnostics for lowering to chalk tys, since the input to that is `TypeRef`.
This means that `TypeRef`s now have an identity, which means storing them in arena and not interning them, which is an unfortunate (but necessary) loss but also a pretty massive change. Luckily, because of the separation layer we have for IDE and HIR, this change never crosses the IDE boundary.
Or macro_rules hygiene, or mixed site hygiene. In other words, hygiene for variables and labels but not items.
The realization that made me implement this was that while "full" hygiene (aka. def site hygiene) is really hard for us to implement, and will likely involve intrusive changes and performance losses, since every `Name` will have to carry hygiene, mixed site hygiene is very local: it applies only to bodies, and we very well can save it in a side map with minor losses.
This fixes one diagnostic in r-a that was about `izip!()` using hygiene (yay!) but it introduces a huge number of others, because of #18262. Up until now this issue wasn't a major problem because it only affected few cases, but with hygiene identifiers referred by macros like that are not resolved at all. The next commit will fix that.
And few more fixups.
I was worried this will lead to more memory usage since `ExprOrPatId` is double the size of `ExprId`, but this does not regress `analysis-stats .`. If this turns out to be a problem, we can easily use the high bit to encode this information.
Instead of lowering them to `<expr> = <expr>`, then hacking on-demand to resolve them, we lower them to `<pat> = <expr>`, and use the pattern infrastructure to handle them. It turns out, destructuring assignments are surprisingly similar to pattern bindings, and so only minor modifications are needed.
This fixes few bugs that arose because of the non-uniform handling (for example, MIR lowering not handling slice and record patterns, and closure capture calculation not handling destructuring assignments at all), and furthermore, guarantees we won't have such bugs in the future, since the programmer will always have to explicitly handle `Expr::Assignment`.
Tests don't pass yet; that's because the generated patterns do not exist in the source map. The next commit will fix that.
internal: add json `tracing` Layer for profiling startup
On `buck2/integrations/rust-project`, this results in the following being printed:
```json
{"name":"discover_command","elapsed_ms":18703}
{"name":"parallel_prime_caches","elapsed_ms":0}
{"name":"vfs_load","elapsed_ms":5895}
{"name":"vfs_load","elapsed_ms":547}
{"name":"parallel_prime_caches","elapsed_ms":23}
{"name":"parallel_prime_caches","elapsed_ms":84}
{"name":"parallel_prime_caches","elapsed_ms":5819}
```
fix: Fix resolution of label inside macro
When working on Something Else (TM) (I left a hint in the commits :P), I noticed to my surprise that labels inside macros are not resolved. This led to a discovery of *two* unrelated bugs, which are hereby fixed in two commits.
This fixes a bug where labels inside macros were not resolved, but more importantly this prepares us to a future where we have hygiene, and textual equivalence isn't enough to resolve identifiers.
fix: Get rid of `$crate` in expansions shown to the user
Be it "Expand Macro Recursively", "Inline macro" or few other things.
We replace it with the crate name, as should've always been.
Probably fixes some issues, but I don't know what they are.
fix: Always cache macro expansions' root node in Semantics
Previously some expansions were not cached, but were cached in the expansion cache, which caused panics when later queries tried to lookup the node from the expansion cache.
Fixes#18089.
Previously some expansions were not cached, but were cached in the expansion cache, which caused panics when later queries tried to lookup the node from the expansion cache.
