Codechange: allow string temporaries in a StringParameter

src/strings.cpp

@@ -363,6 +363,18 @@ void SetDParamStr(size_t n, const std::string &str)
 	_global_string_params.SetParam(n, str);
 }
 
+/**
+ * This function is used to "bind" the std::string to a OpenTTD dparam slot.
+ * Contrary to the other \c SetDParamStr functions, this moves the string into
+ * the parameter slot.
+ * @param n slot of the string
+ * @param str string to bind
+ */
+void SetDParamStr(size_t n, std::string &&str)
+{
+	_global_string_params.SetParam(n, std::move(str));
+}
+
 /**
  * Format a number into a string.
  * @param builder   the string builder to write to

src/strings_func.h

@@ -84,7 +84,7 @@ void SetDParamMaxDigits(size_t n, uint count, FontSize size = FS_NORMAL);
 
 void SetDParamStr(size_t n, const char *str);
 void SetDParamStr(size_t n, const std::string &str);
-void SetDParamStr(size_t n, std::string &&str) = delete; // block passing temporaries to SetDParamStr
+void SetDParamStr(size_t n, std::string &&str);
 
 void CopyInDParam(const span<const StringParameterBackup> backup);
 void CopyOutDParam(std::vector<StringParameterBackup> &backup, size_t num);

src/strings_internal.h

@@ -18,6 +18,7 @@
 struct StringParameter {
 	uint64_t data; ///< The data of the parameter.
 	const char *string_view; ///< The string value, if it has any.
+	std::unique_ptr<std::string> string; ///< Copied string value, if it has any.
 	WChar type; ///< The #StringControlCode to interpret this data with when it's the first parameter, otherwise '\0'.
 };
 
@@ -102,7 +103,8 @@ public:
 	const char *GetNextParameterString()
 	{
 		auto ptr = GetNextParameterPointer();
-		return ptr == nullptr ? nullptr : ptr->string_view;
+		if (ptr == nullptr) return nullptr;
+		return ptr->string != nullptr ? ptr->string->c_str() : ptr->string_view;
 	}
 
 	/**
@@ -147,6 +149,7 @@ public:
 	{
 		assert(n < this->parameters.size());
 		this->parameters[n].data = v;
+		this->parameters[n].string.reset();
 		this->parameters[n].string_view = nullptr;
 	}
 
@@ -154,16 +157,24 @@ public:
 	{
 		assert(n < this->parameters.size());
 		this->parameters[n].data = 0;
+		this->parameters[n].string.reset();
 		this->parameters[n].string_view = str;
 	}
 
 	void SetParam(size_t n, const std::string &str) { this->SetParam(n, str.c_str()); }
-	void SetParam(size_t n, std::string &&str) = delete; // block passing temporaries to SetDParam
+
+	void SetParam(size_t n, std::string &&str)
+	{
+		assert(n < this->parameters.size());
+		this->parameters[n].data = 0;
+		this->parameters[n].string = std::make_unique<std::string>(std::move(str));
+		this->parameters[n].string_view = nullptr;
+	}
 
 	uint64 GetParam(size_t n) const
 	{
 		assert(n < this->parameters.size());
-		assert(this->parameters[n].string_view == nullptr);
+		assert(this->parameters[n].string_view == nullptr && this->parameters[n].string == nullptr);
 		return this->parameters[n].data;
 	}
 
@@ -175,7 +186,8 @@ public:
 	const char *GetParamStr(size_t n) const
 	{
 		assert(n < this->parameters.size());
-		return this->parameters[n].string_view;
+		auto &param = this->parameters[n];
+		return param.string != nullptr ? param.string->c_str() : param.string_view;
 	}
 };