[llvm] Support: Add vfs::OutputBackend and OutputFile to virtualize compiler outputs (PR #113363)

[Alexandre Ganea via llvm-commits]

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@@ -0,0 +1,67 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file contains the declarations of the VirtualOutputBackend class.
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aganea wrote:

I would rather have a short paragraph here about what the purpose of this file is, not what classes it declares? Same for the other files. The goal would be to create a quick mental model before actually browsing through the code.

https://github.com/llvm/llvm-project/pull/113363