Merge #7145

7145: Proper handling $crate Take 2 [DO NOT MERGE] r=edwin0cheng a=edwin0cheng

Similar to previous PR (#7133) , but improved the following things :

1. Instead of storing the whole `ExpansionInfo`, we store a similar but stripped version `HygieneInfo`.
2. Instread of storing the `SyntaxNode` (because every token we are interested are IDENT), we store the `TextRange` only.
3. Because of 2, we now can put it in Salsa.
4. And most important improvement: Instead of computing the whole frames every single time, we compute it recursively through salsa: (Such that in the best scenario, we only need to compute the first layer of frame)

```rust
        let def_site = db.hygiene_frame(info.def.file_id);
        let call_site = db.hygiene_frame(info.arg.file_id);

        HygieneFrame { expansion: Some(info), local_inner, krate, call_site, def_site }
```

The overall speed compared to previous PR is much faster (65s vs 45s) :
```
[WITH old PR]
Database loaded 644.86ms, 284mi
Crates in this dir: 36
Total modules found: 576
Total declarations: 11153
Total functions: 8715
Item Collection: 15.78s, 91562mi
Total expressions: 240721
Expressions of unknown type: 2635 (1%)
Expressions of partially unknown type: 2064 (0%)
Type mismatches: 865
Inference: 49.84s, 250747mi
Total: 65.62s, 342310mi
rust-analyzer -q analysis-stats .  66.72s user 0.57s system 99% cpu 1:07.40 total

[WITH this PR]
Database loaded 665.83ms, 284mi
Crates in this dir: 36
Total modules found: 577
Total declarations: 11188
Total functions: 8743
Item Collection: 15.28s, 84919mi
Total expressions: 241229
Expressions of unknown type: 2637 (1%)
Expressions of partially unknown type: 2064 (0%)
Type mismatches: 868
Inference: 30.15s, 135293mi
Total: 45.43s, 220213mi   
rust-analyzer -q analysis-stats .  46.26s user 0.74s system 99% cpu 47.294 total
```

*HOWEVER*,  it is still a perf regression (35s vs 45s):
```
[WITHOUT this PR]
Database loaded 657.42ms, 284mi
Crates in this dir: 36
Total modules found: 577
Total declarations: 11177
Total functions: 8735
Item Collection: 12.87s, 72407mi
Total expressions: 239380
Expressions of unknown type: 2643 (1%)
Expressions of partially unknown type: 2064 (0%)
Type mismatches: 868
Inference: 22.88s, 97889mi
Total: 35.74s, 170297mi
rust-analyzer -q analysis-stats .  36.71s user 0.63s system 99% cpu 37.498 total
```



Co-authored-by: Edwin Cheng <[email protected]>

3 files changed, 14 insertions, 19 deletions

diff --git a/crates/mbe/src/mbe_expander/matcher.rs b/crates/mbe/src/mbe_expander/matcher.rs
index fdc8844ce..c6d615c81 100644
--- a/crates/mbe/src/mbe_expander/matcher.rs
+++ b/crates/mbe/src/mbe_expander/matcher.rs
@@ -150,7 +150,7 @@ fn match_subtree(
                     res.add_err(err!("leftover tokens"));
                 }
             }
-            Op::Var { name, kind } => {
+            Op::Var { name, kind, .. } => {
                 let kind = match kind {
                     Some(k) => k,
                     None => {
diff --git a/crates/mbe/src/mbe_expander/transcriber.rs b/crates/mbe/src/mbe_expander/transcriber.rs
index 720531237..57f3f104d 100644
--- a/crates/mbe/src/mbe_expander/transcriber.rs
+++ b/crates/mbe/src/mbe_expander/transcriber.rs
@@ -100,8 +100,8 @@ fn expand_subtree(
                 err = err.or(e);
                 arena.push(tt.into());
             }
-            Op::Var { name, .. } => {
-                let ExpandResult { value: fragment, err: e } = expand_var(ctx, &name);
+            Op::Var { name, id, .. } => {
+                let ExpandResult { value: fragment, err: e } = expand_var(ctx, &name, *id);
                 err = err.or(e);
                 push_fragment(arena, fragment);
             }
@@ -118,12 +118,10 @@ fn expand_subtree(
     ExpandResult { value: tt::Subtree { delimiter: template.delimiter, token_trees: tts }, err }
 }
 
-fn expand_var(ctx: &mut ExpandCtx, v: &SmolStr) -> ExpandResult<Fragment> {
+fn expand_var(ctx: &mut ExpandCtx, v: &SmolStr, id: tt::TokenId) -> ExpandResult<Fragment> {
     if v == "crate" {
         // We simply produce identifier `$crate` here. And it will be resolved when lowering ast to Path.
-        let tt =
-            tt::Leaf::from(tt::Ident { text: "$crate".into(), id: tt::TokenId::unspecified() })
-                .into();
+        let tt = tt::Leaf::from(tt::Ident { text: "$crate".into(), id }).into();
         ExpandResult::ok(Fragment::Tokens(tt))
     } else if !ctx.bindings.contains(v) {
         // Note that it is possible to have a `$var` inside a macro which is not bound.
@@ -142,14 +140,8 @@ fn expand_var(ctx: &mut ExpandCtx, v: &SmolStr) -> ExpandResult<Fragment> {
         let tt = tt::Subtree {
             delimiter: None,
             token_trees: vec![
-                tt::Leaf::from(tt::Punct {
-                    char: '$',
-                    spacing: tt::Spacing::Alone,
-                    id: tt::TokenId::unspecified(),
-                })
-                .into(),
-                tt::Leaf::from(tt::Ident { text: v.clone(), id: tt::TokenId::unspecified() })
-                    .into(),
+                tt::Leaf::from(tt::Punct { char: '$', spacing: tt::Spacing::Alone, id }).into(),
+                tt::Leaf::from(tt::Ident { text: v.clone(), id }).into(),
             ],
         }
         .into();
diff --git a/crates/mbe/src/parser.rs b/crates/mbe/src/parser.rs
index 2f3ebc831..77cc739b6 100644
--- a/crates/mbe/src/parser.rs
+++ b/crates/mbe/src/parser.rs
@@ -8,7 +8,7 @@ use crate::{tt_iter::TtIter, ExpandError, MetaTemplate};
 
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub(crate) enum Op {
-    Var { name: SmolStr, kind: Option<SmolStr> },
+    Var { name: SmolStr, kind: Option<SmolStr>, id: tt::TokenId },
     Repeat { subtree: MetaTemplate, kind: RepeatKind, separator: Option<Separator> },
     Leaf(tt::Leaf),
     Subtree(MetaTemplate),
@@ -106,18 +106,21 @@ fn next_op<'a>(first: &tt::TokenTree, src: &mut TtIter<'a>, mode: Mode) -> Resul
                         }
                         let name = UNDERSCORE.clone();
                         let kind = eat_fragment_kind(src, mode)?;
-                        Op::Var { name, kind }
+                        let id = punct.id;
+                        Op::Var { name, kind, id }
                     }
                     tt::Leaf::Ident(ident) => {
                         let name = ident.text.clone();
                         let kind = eat_fragment_kind(src, mode)?;
-                        Op::Var { name, kind }
+                        let id = ident.id;
+                        Op::Var { name, kind, id }
                     }
                     tt::Leaf::Literal(lit) => {
                         if is_boolean_literal(&lit) {
                             let name = lit.text.clone();
                             let kind = eat_fragment_kind(src, mode)?;
-                            Op::Var { name, kind }
+                            let id = lit.id;
+                            Op::Var { name, kind, id }
                         } else {
                             bail!("bad var 2");
                         }