[Support] Make all Errors convertible to std::error_code.

This is a temporary crutch to enable code that currently uses std::error_code
to be incrementally moved over to Error. Requiring all Error instances be
convertible enables clients to call errorToErrorCode on any error (not just
ECErrors created by conversion *from* an error_code).

This patch also moves code for Error from ErrorHandling.cpp into a new
Error.cpp file.

llvm-svn: 264221

3 files changed, 46 insertions, 3 deletions

diff --git a/llvm/lib/Support/CMakeLists.txt b/llvm/lib/Support/CMakeLists.txt
index d14d7d305fd..98108e54cf2 100644
--- a/llvm/lib/Support/CMakeLists.txt
+++ b/llvm/lib/Support/CMakeLists.txt
@@ -48,6 +48,7 @@ add_llvm_library(LLVMSupport
   DeltaAlgorithm.cpp
   DAGDeltaAlgorithm.cpp
   Dwarf.cpp
+  Error.cpp
   ErrorHandling.cpp
   FileUtilities.cpp
   FileOutputBuffer.cpp
diff --git a/llvm/lib/Support/Error.cpp b/llvm/lib/Support/Error.cpp
new file mode 100644
index 00000000000..0cf50153c0e
--- /dev/null
+++ b/llvm/lib/Support/Error.cpp
@@ -0,0 +1,45 @@
+//===----- lib/Support/Error.cpp - Error and associated utilities ---------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/Error.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/ManagedStatic.h"
+
+using namespace llvm;
+
+namespace {
+
+  enum class ErrorErrorCode {
+    MultipleErrors
+  };
+
+  class ErrorErrorCategory : public std::error_category {
+  public:
+    const char *name() const LLVM_NOEXCEPT override { return "Error"; }
+
+    std::string message(int condition) const override {
+      switch (static_cast<ErrorErrorCode>(condition)) {
+      case ErrorErrorCode::MultipleErrors:
+        return "Multiple errors";
+      };
+      llvm_unreachable("Unhandled error code");
+    }
+  };
+
+};
+
+void ErrorInfoBase::anchor() {}
+char ErrorInfoBase::ID = 0;
+
+static ManagedStatic<ErrorErrorCategory> ErrorErrorCat;
+
+std::error_code ErrorList::convertToErrorCode() const {
+  return std::error_code(static_cast<int>(ErrorErrorCode::MultipleErrors),
+                         *ErrorErrorCat);
+}
diff --git a/llvm/lib/Support/ErrorHandling.cpp b/llvm/lib/Support/ErrorHandling.cpp
index c743d388887..a7d3a18003e 100644
--- a/llvm/lib/Support/ErrorHandling.cpp
+++ b/llvm/lib/Support/ErrorHandling.cpp
@@ -139,9 +139,6 @@ void LLVMResetFatalErrorHandler() {
   remove_fatal_error_handler();
 }
 
-void ErrorInfoBase::anchor() {}
-char ErrorInfoBase::ID = 0;
-
 #ifdef LLVM_ON_WIN32
 
 #include <winerror.h>