Simple function for creating Expected<> with nice error messages.

Signed-off-by: Anton Johansson <anjo@rev.ng>
---
 subprojects/helper-to-tcg/include/Error.h | 40 +++++++++++++++++++++++
 1 file changed, 40 insertions(+)
 create mode 100644 subprojects/helper-to-tcg/include/Error.h

diff --git a/subprojects/helper-to-tcg/include/Error.h b/subprojects/helper-to-tcg/include/Error.h
new file mode 100644
index 0000000000..10205e29a6
--- /dev/null
+++ b/subprojects/helper-to-tcg/include/Error.h
@@ -0,0 +1,40 @@
+//
+//  Copyright(c) 2024 rev.ng Labs Srl. All Rights Reserved.
+//
+//  This program is free software; you can redistribute it and/or modify
+//  it under the terms of the GNU General Public License as published by
+//  the Free Software Foundation; either version 2 of the License, or
+//  (at your option) any later version.
+//
+//  This program is distributed in the hope that it will be useful,
+//  but WITHOUT ANY WARRANTY; without even the implied warranty of
+//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//  GNU General Public License for more details.
+//
+//  You should have received a copy of the GNU General Public License
+//  along with this program; if not, see <http://www.gnu.org/licenses/>.
+//
+
+#pragma once
+
+#include <llvm/Support/Error.h>
+#include <llvm/IR/Value.h>
+#include <llvm/IR/ModuleSlotTracker.h>
+
+inline llvm::Error mkError(const llvm::StringRef Msg)
+{
+    return llvm::createStringError(llvm::inconvertibleErrorCode(), Msg);
+}
+
+// TODO: Usage of mkError and dbgs() for serializing Values is __really__ slow,
+// and should only occur for error reporting.  Wrap these in a class with a
+// ModuleSlotTracker.
+inline llvm::Error mkError(const llvm::StringRef Msg, const llvm::Value *V)
+{
+    std::string Str;
+    llvm::raw_string_ostream Stream(Str);
+    Stream << Msg;
+    Stream << *V;
+    Stream.flush();
+    return llvm::createStringError(llvm::inconvertibleErrorCode(), Str);
+}
-- 
2.45.2