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

[Adrian Prantl via llvm-commits]

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@@ -0,0 +1,139 @@
+//===----------------------------------------------------------------------===//
+//
+// 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 OutputError class.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_VIRTUALOUTPUTERROR_H
+#define LLVM_SUPPORT_VIRTUALOUTPUTERROR_H
+
+#include "llvm/Support/Error.h"
+#include "llvm/Support/VirtualOutputConfig.h"
+
+namespace llvm::vfs {
+
+const std::error_category &output_category();
+
+enum class OutputErrorCode {
+  // Error code 0 is absent. Use std::error_code() instead.
+  not_closed = 1,
+  invalid_config,
+  already_closed,
+  has_open_proxy,
+};
+
+inline std::error_code make_error_code(OutputErrorCode EV) {
+  return std::error_code(static_cast<int>(EV), output_category());
+}
+
+/// Error related to an \a OutputFile. Derives from \a ECError and adds \a
+/// getOutputPath().
+class OutputError : public ErrorInfo<OutputError, ECError> {
+  void anchor() override;
+
+public:
+  StringRef getOutputPath() const { return OutputPath; }
+  void log(raw_ostream &OS) const override {
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adrian-prantl wrote:

move this to cpp file?

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