fix(rt): Handle zero-sized locals on borrow

Author: Stevengre

kmir/src/kmir/kdist/mir-semantics/rt/data.md

@@ -1073,14 +1073,7 @@ This eliminates any `Deref` projections from the place, and also resolves `Index
 
   // Borrowing a zero-sized local that is still `NewLocal`: initialise it, then reuse the regular rule.
   rule <k> rvalueRef(REGION, KIND, place(local(I), PROJS))
-        => #forceSetLocal(
-              local(I),
-              #decodeConstant(
-                constantKindZeroSized,
-                tyOfLocal(getLocal(LOCALS, I)),
-                lookupTy(tyOfLocal(getLocal(LOCALS, I)))
-              )
-            )
+        => #forceSetLocal(local(I), Aggregate(variantIdx(0), .List))
         ~> rvalueRef(REGION, KIND, place(local(I), PROJS))
        ...
        </k>

kmir/src/kmir/kdist/mir-semantics/rt/types.md

@@ -148,7 +148,7 @@ Slices, `str`s  and dynamic types require it, and any `Ty` that `is_sized` does
 ```k
   syntax Bool ::= #zeroSizedType ( TypeInfo ) [function, total]
 
-  rule #zeroSizedType(typeInfoTupleType(.Tys, _)) => true
+  rule #zeroSizedType(typeInfoTupleType(.Tys)) => true
   rule #zeroSizedType(typeInfoStructType(_, _, .Tys, _)) => true
   rule #zeroSizedType(typeInfoVoidType) => true
   // FIXME: Only unit tuples, empty structs, and void are recognized here; other