Merge #8813

8813: Get some more array lengths! r=lf- a=lf-

This is built on #8799 and thus contains its changes. I'll rebase it onto master when that one gets merged. It adds support for r-a understanding the length of:

* `let a: [u8; 2] = ...`
* `let a = b"aaa"`
* `let a = [0u8; 4]`

I have added support for getting the values of byte strings, which was not previously there. I am least confident in the correctness of this part and it probably needs some more tests, as we currently have only one test that exercised that part (!).

Fixes #2922.

Co-authored-by: Jade <[email protected]>

1 files changed, 4 insertions, 1 deletions

diff --git a/crates/hir/src/lib.rs b/crates/hir/src/lib.rs
index 6233bca83..d443b124c 100644
--- a/crates/hir/src/lib.rs
+++ b/crates/hir/src/lib.rs
@@ -52,7 +52,9 @@ use hir_def::{
 };
 use hir_expand::{diagnostics::DiagnosticSink, name::name, MacroDefKind};
 use hir_ty::{
-    autoderef, could_unify,
+    autoderef,
+    consteval::ConstExt,
+    could_unify,
     method_resolution::{self, def_crates, TyFingerprint},
     primitive::UintTy,
     subst_prefix,
@@ -1914,6 +1916,7 @@ impl Type {
                     substs.iter(&Interner).filter_map(|a| a.ty(&Interner)).any(go)
                 }
 
+                TyKind::Array(_ty, len) if len.is_unknown() => true,
                 TyKind::Array(ty, _)
                 | TyKind::Slice(ty)
                 | TyKind::Raw(_, ty)