Replace std::ostringstream usage with fmt::format

Source/Core/InputCommon/ControllerInterface/CoreDevice.cpp

@@ -162,15 +162,12 @@ void Device::AddCombinedInput(std::string name, const std::pair<std::string, std
 std::string DeviceQualifier::ToString() const
 {
   if (source.empty() && (cid < 0) && name.empty())
-    return "";
+    return {};
 
-  std::ostringstream ss;
-  ss << source << '/';
   if (cid > -1)
-    ss << cid;
-  ss << '/' << name;
-
-  return ss.str();
+    return fmt::format("{}/{}/{}", source, cid, name);
+  else
+    return fmt::format("{}//{}", source, name);
 }
 
 //

Source/Core/InputCommon/ControllerInterface/DInput/DInputJoystick.cpp

@@ -7,9 +7,10 @@
 #include <limits>
 #include <mutex>
 #include <set>
-#include <sstream>
 #include <type_traits>
 
+#include <fmt/format.h>
+
 #include "Common/HRWrap.h"
 #include "Common/Logging/Log.h"
 #include "InputCommon/ControllerInterface/ControllerInterface.h"
@@ -266,37 +267,21 @@ void Joystick::UpdateInput()
 
 std::string Joystick::Button::GetName() const
 {
-  std::ostringstream ss;
-  ss << "Button " << (int)m_index;
-  return ss.str();
+  return fmt::format("Button {}", m_index);
 }
 
 std::string Joystick::Axis::GetName() const
 {
-  std::ostringstream ss;
-  // axis
-  if (m_index < 6)
-  {
-    ss << "Axis " << (char)('X' + (m_index % 3));
-    if (m_index > 2)
-      ss << 'r';
-  }
-  // slider
-  else
-  {
-    ss << "Slider " << (int)(m_index - 6);
-  }
-
-  ss << (m_range < 0 ? '-' : '+');
-  return ss.str();
+  const char sign = m_range < 0 ? '-' : '+';
+  if (m_index < 6)  // axis
+    return fmt::format("Axis {:c}{}{:c}", 'X' + m_index % 3, m_index > 2 ? "r" : "", sign);
+  else  // slider
+    return fmt::format("Slider {}{:c}", m_index - 6, sign);
 }
 
 std::string Joystick::Hat::GetName() const
 {
-  char tmpstr[] = "Hat . .";
-  tmpstr[4] = (char)('0' + m_index);
-  tmpstr[6] = "NESW"[m_direction];
-  return tmpstr;
+  return fmt::format("Hat {} {:c}", m_index, "NESW"[m_direction]);
 }
 
 // get / set state