IndexOutOfRangeException in indexed getter

Question

In my indexed property I check whether the index is out of bounds or not. If it is, I throw an IndexOutOfBoundsException.

When I run the Code Analyst (in VS12) it complains with CA1065: Unexpected exception in unexpected location.

Referring to the description of CA1065, only

System.InvalidOperationException
System.NotSupportedException
System.ArgumentException
KeyNotFoundException

are allowed in an indexed getter.

Throwing IndexOutOfBoundsException seems natural to me, so what is the reasoning here? (And yes, I know I can turn the warning off, I just want to know the reasoning)

Answer 1

A lot of classes use ArgumentOutOfRangeException for this, including List<T>. This is a subclass of ArgumentException so should satisfy the rule. I guess you could argue that for a vector etc accessed directly, there isn't actually a method call (it is a dedicated opcode - ldelem*), so the index in that case isn't actually an argument. Seems a weak argument, though.

Answer 2

See MSDN: IndexOutOfRangeException is system exception and reserved for accessing array elements. It is thrown by some MSIL instructions: ldelem., ldelema, stelem..

For developing classes use ArgumentOutOfRangeException.