Add lowering of array lengths in types

Now e.g.

```rust
fn a(b: [u8; 2]) {
}
```

will know about the length of b.

1 files changed, 4 insertions, 4 deletions

diff --git a/crates/hir_ty/src/tests/patterns.rs b/crates/hir_ty/src/tests/patterns.rs
index 33305f208..b36e77e91 100644
--- a/crates/hir_ty/src/tests/patterns.rs
+++ b/crates/hir_ty/src/tests/patterns.rs
@@ -345,19 +345,19 @@ fn infer_pattern_match_arr() {
         "#,
         expect![[r#"
             10..179 '{     ...   } }': ()
-            20..23 'arr': [f64; _]
+            20..23 'arr': [f64; 2]
             36..46 '[0.0, 1.0]': [f64; 2]
             37..40 '0.0': f64
             42..45 '1.0': f64
             52..177 'match ...     }': ()
-            58..61 'arr': [f64; _]
-            72..80 '[1.0, a]': [f64; _]
+            58..61 'arr': [f64; 2]
+            72..80 '[1.0, a]': [f64; 2]
             73..76 '1.0': f64
             73..76 '1.0': f64
             78..79 'a': f64
             84..110 '{     ...     }': ()
             98..99 'a': f64
-            120..126 '[b, c]': [f64; _]
+            120..126 '[b, c]': [f64; 2]
             121..122 'b': f64
             124..125 'c': f64
             130..171 '{     ...     }': ()