Build from source fails with errors C4834 and MSB3073

Development Getting Started & Setup
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Hi @ptitbgdu80 and @Anonymous_c0b2ef1d8b6296d661f82020eeaf73de,
Removing line 513 is not really a solution to the problem.

This is a bug in the UE code on line 513.
It should probably be:

GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Red, FString::Printf(TEXT("Unable to find Action [%s] for Action Set [%s]"), *ActionName.ToString(), *ActionSet.ToString()));

instead of:

GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Red, (TEXT("Unable to find Action [%s] for Action Set [%s]"), *ActionName.ToString(), *ActionSet.ToString()));

Actually the problem is in the substring:

(TEXT("Unable to find Action [%s] for Action Set [%s]"), *ActionName.ToString(), *ActionSet.ToString())

This line is like:

const TCHAR *value = (TEXT("some value"), name1.CalculateString(), name2.CalculateString());

or

auto a = (op1(), op2(), op3());

the results of calling op1 and op2 will be ignored, but only op3() will be assigned to a.
So, if op1 or op2 has a “nodiscard” attribute, Visual Studio will generate an error/warning.
The previous version of Visual Studio did not have this behavior. New Visual Studio update - has.

The actual nodiscard attribute that can cause this error in this situation is UnrealString.h, line 324:

	/**
	 * Get pointer to the string
	 *
	 * @Return Pointer to Array of TCHAR if Num, otherwise the empty string
	 */
	UE_NODISCARD FORCEINLINE const TCHAR* operator*() const UE_LIFETIMEBOUND
	{
		return Data.Num() ? Data.GetData() : TEXT("");
	}

To sum up, the solution would be to use this line instead of line 513:

GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Red, FString::Printf(TEXT("Unable to find Action [%s] for Action Set [%s]"), *ActionName.ToString(), *ActionSet.ToString()));
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