[obj2yaml] Recognize input file format using llvm::object::ObjectFile
interface methods isCOFF().

The '-coff' command line option has been removed. It was not used in any
test cases.

The patch reviewed by Michael Spencer.

llvm-svn: 208157
diff --git a/llvm/tools/obj2yaml/Error.cpp b/llvm/tools/obj2yaml/Error.cpp
new file mode 100644
index 0000000..7be468d
--- /dev/null
+++ b/llvm/tools/obj2yaml/Error.cpp
@@ -0,0 +1,54 @@
+//===- Error.cpp - system_error extensions for obj2yaml ---------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "Error.h"
+#include "llvm/Support/ErrorHandling.h"
+
+using namespace llvm;
+
+namespace {
+class _obj2yaml_error_category : public error_category {
+public:
+  const char *name() const override;
+  std::string message(int ev) const override;
+  error_condition default_error_condition(int ev) const override;
+};
+} // namespace
+
+const char *_obj2yaml_error_category::name() const { return "obj2yaml"; }
+
+std::string _obj2yaml_error_category::message(int ev) const {
+  switch (ev) {
+  case obj2yaml_error::success:
+    return "Success";
+  case obj2yaml_error::file_not_found:
+    return "No such file.";
+  case obj2yaml_error::unrecognized_file_format:
+    return "Unrecognized file type.";
+  case obj2yaml_error::unsupported_obj_file_format:
+    return "Unsupported object file format.";
+  default:
+    llvm_unreachable("An enumerator of obj2yaml_error does not have a message "
+                     "defined.");
+  }
+}
+
+error_condition
+_obj2yaml_error_category::default_error_condition(int ev) const {
+  if (ev == obj2yaml_error::success)
+    return errc::success;
+  return errc::invalid_argument;
+}
+
+namespace llvm {
+const error_category &obj2yaml_category() {
+  static _obj2yaml_error_category o;
+  return o;
+}
+} // namespace llvm