INI parsing with std::from_chars throws exception for value that is out of range

[Caball009]

• perf(ini): Improve INI parsing performance by using std::from_chars #2532

The Shockwave mod contains invalid data in one of its ini files: "Data\INI\Object\china\infantry\infantry\minigunnersquad.ini":

SpawnReplaceDelay = 9999999999999999999 ; 5 Years

This value is out of range for uint32, our refactored code detects this and throws an exception for invalid ini data. This means that the Shockwave mod cannot be played when the project is compiled with C++17 support. This also applies to Generals Online.

A workaround is to set USE_STD_FROM_CHARS_PARSING to 0.

[Caball009]

GeneralsGameCode/Core/GameEngine/Source/Common/INI/INI.cpp

Lines 1620 to 1623 in 82f4b85

	if (ec != std::errc{})
	{
	throw INI_INVALID_DATA;
	}

This could be changed to

// #include <limits>

if (ec != std::errc{})
{
	if (ec == std::errc::result_out_of_range)
	{
		return std::numeric_limits<Type>::max();
	}

	throw INI_INVALID_DATA;
}

I see one potential issue with that. I assume that the code base can be compiled with C++11 / 14. Such builds would still use sscanf instead of std::from_chars and there would be a discrepancy in the way that the parser handles values that are out of range. I don't think it's made clear that the game logic can be different between C++11 / 14 and >= C++17.