loader: Make ResultStatus directly compatible with fmt

We can make the enum class type compatible with fmt by providing an
overload of operator<<.

While we're at it, perform proper bounds checking. If something exceeds
the array, it should be a hard fail, because it's, without a doubt, a
programmer error in this case.

2 files changed, 6 insertions, 10 deletions

diff --git a/src/core/loader/loader.cpp b/src/core/loader/loader.cpp
index b143f043cd..5e07a3f107 100644
--- a/src/core/loader/loader.cpp
+++ b/src/core/loader/loader.cpp
@@ -3,6 +3,7 @@
 // Refer to the license.txt file included.
 
 #include <memory>
+#include <ostream>
 #include <string>
 #include "common/logging/log.h"
 #include "common/string_util.h"
@@ -119,14 +120,9 @@ constexpr std::array<const char*, 36> RESULT_MESSAGES{
     "There is no control data available.",
 };
 
-std::string GetMessageForResultStatus(ResultStatus status) {
-    return GetMessageForResultStatus(static_cast<u16>(status));
-}
-
-std::string GetMessageForResultStatus(u16 status) {
-    if (status >= 36)
-        return "";
-    return RESULT_MESSAGES[status];
+std::ostream& operator<<(std::ostream& os, ResultStatus status) {
+    os << RESULT_MESSAGES.at(static_cast<size_t>(status));
+    return os;
 }
 
 /**
diff --git a/src/core/loader/loader.h b/src/core/loader/loader.h
index 6dffe451a6..b74cfbf8a8 100644
--- a/src/core/loader/loader.h
+++ b/src/core/loader/loader.h
@@ -5,6 +5,7 @@
 #pragma once
 
 #include <algorithm>
+#include <iosfwd>
 #include <memory>
 #include <string>
 #include <utility>
@@ -94,8 +95,7 @@ enum class ResultStatus : u16 {
     ErrorNoControl,
 };
 
-std::string GetMessageForResultStatus(ResultStatus status);
-std::string GetMessageForResultStatus(u16 status);
+std::ostream& operator<<(std::ostream& os, ResultStatus status);
 
 /// Interface for loading an application
 class AppLoader : NonCopyable {