Add basic support for array lengths in types

This recognizes `let a = [1u8, 2, 3]` as having type `[u8; 3]` instead
of the previous `[u8; _]`. Byte strings and `[0u8; 2]` kinds of range
array declarations are unsupported as before.

I don't know why a bunch of our rustc tests had single quotes inside
strings un-escaped by `UPDATE_EXPECT=1 cargo t`, but I don't think it's
bad? Maybe something in a nightly?

1 files changed, 1 insertions, 1 deletions

diff --git a/crates/hir_ty/src/tests/traits.rs b/crates/hir_ty/src/tests/traits.rs
index ffc7c8ef4..47a1455fd 100644
--- a/crates/hir_ty/src/tests/traits.rs
+++ b/crates/hir_ty/src/tests/traits.rs
@@ -531,7 +531,7 @@ fn indexing_arrays() {
         expect![[r#"
             10..26 '{ &mut...[2]; }': ()
             12..23 '&mut [9][2]': &mut {unknown}
-            17..20 '[9]': [i32; _]
+            17..20 '[9]': [i32; 1]
             17..23 '[9][2]': {unknown}
             18..19 '9': i32
             21..22 '2': i32