SmallString: Make constructors explicit

Catch more errors at compile-time.

src/common/small_string.h

@@ -266,13 +266,13 @@ class SmallStackString : public SmallStringBase
 public:
   ALWAYS_INLINE SmallStackString() { init(); }
 
-  ALWAYS_INLINE SmallStackString(const char* str)
+  ALWAYS_INLINE explicit SmallStackString(const char* str)
   {
     init();
     assign(str);
   }
 
-  ALWAYS_INLINE SmallStackString(const char* str, u32 length)
+  ALWAYS_INLINE explicit SmallStackString(const char* str, u32 length)
   {
     init();
     assign(str, length);
@@ -290,19 +290,25 @@ public:
     assign(move);
   }
 
-  ALWAYS_INLINE SmallStackString(const SmallStackString& copy)
+  ALWAYS_INLINE explicit SmallStackString(const SmallStackString& copy)
   {
     init();
     assign(copy);
   }
 
-  ALWAYS_INLINE SmallStackString(SmallStackString&& move)
+  ALWAYS_INLINE explicit SmallStackString(SmallStackString&& move)
   {
     init();
     assign(move);
   }
 
-  ALWAYS_INLINE SmallStackString(const std::string_view sv)
+  ALWAYS_INLINE explicit SmallStackString(const std::string& str)
+  {
+    init();
+    assign(str);
+  }
+
+  ALWAYS_INLINE explicit SmallStackString(const std::string_view sv)
   {
     init();
     assign(sv);
@@ -332,6 +338,12 @@ public:
     return *this;
   }
 
+  ALWAYS_INLINE SmallStackString& operator=(const std::string& str)
+  {
+    assign(str);
+    return *this;
+  }
+
   ALWAYS_INLINE SmallStackString& operator=(const std::string_view sv)
   {
     assign(sv);

src/core/achievements.cpp

@@ -3815,7 +3815,7 @@ static TinyString GetLoginEncryptionMachineKey()
   {
     WARNING_LOG("Get MachineGuid failed: {}", error);
     RegCloseKey(hKey);
-    return 0;
+    return ret;
   }
 
   ret.resize(machine_guid_length);
@@ -3826,7 +3826,7 @@ static TinyString GetLoginEncryptionMachineKey()
     WARNING_LOG("Read MachineGuid failed: {}", error);
     ret = {};
     RegCloseKey(hKey);
-    return 0;
+    return ret;
   }
 
   ret.resize(machine_guid_length);

src/core/system.cpp

@@ -6192,7 +6192,7 @@ void System::UpdateRichPresence(bool update_session_time)
   rp.largeImageText = "DuckStation PS1/PSX Emulator";
   rp.startTimestamp = s_state.discord_presence_time_epoch;
 
-  TinyString game_details = "No Game Running";
+  TinyString game_details("No Game Running");
   if (IsValidOrInitializing())
   {
     // Use disc set name if it's not a custom title.

src/util/cubeb_audio_stream.cpp

@@ -59,7 +59,8 @@ static TinyString GetCubebErrorString(int rv)
     C(CUBEB_ERROR_DEVICE_UNAVAILABLE);
 
     default:
-      return "CUBEB_ERROR_UNKNOWN";
+      ret = "CUBEB_ERROR_UNKNOWN";
+      break;
 
 #undef C
   }

src/util/vulkan_swap_chain.cpp

@@ -249,7 +249,7 @@ std::optional<VkSurfaceFormatKHR> VulkanSwapChain::SelectSurfaceFormat(VkPhysica
       return VkSurfaceFormatKHR{format, VK_COLOR_SPACE_SRGB_NONLINEAR_KHR};
   }
 
-  SmallString errormsg = "Failed to find a suitable format for swap chain buffers. Available formats were:";
+  SmallString errormsg("Failed to find a suitable format for swap chain buffers. Available formats were:");
   for (const VkSurfaceFormatKHR& sf : surface_formats)
     errormsg.append_format(" {}", static_cast<unsigned>(sf.format));
   Error::SetStringView(error, errormsg);