[llvm] [CAS] Add LLVMCAS library with InMemoryCAS implementation (PR #114096)

[Paul Kirth via llvm-commits]

================
@@ -0,0 +1,195 @@
+//===- llvm/CAS/CASReference.h ----------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CAS_CASREFERENCE_H
+#define LLVM_CAS_CASREFERENCE_H
+
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/DenseMapInfo.h"
+#include "llvm/ADT/StringRef.h"
+
+namespace llvm {
+
+class raw_ostream;
+
+namespace cas {
+
+class ObjectStore;
+
+class ObjectHandle;
+class ObjectRef;
----------------
ilovepi wrote:

```suggestion
class ObjectStore;
class ObjectHandle;
class ObjectRef;
```
nit: No need for the empty line.

https://github.com/llvm/llvm-project/pull/114096