rspec/rules/S2291/csharp/rule.adoc

== Why is this an issue?

``++Enumerable.Sum()++`` always executes addition in a ``++checked++`` context, so an ``++OverflowException++`` will be thrown if the value exceeds ``++MaxValue++`` even if an ``++unchecked++`` context was specified. Using an ``++unchecked++`` context anyway represents a misunderstanding of how ``++Sum++`` works.


This rule raises an issue when an ``++unchecked++`` context is specified for a ``++Sum++`` on integer types.


=== Noncompliant code example

[source,csharp]
----
void Add(List<int> list)
{
  int d = unchecked(list.Sum());  // Noncompliant

  unchecked 
  {
    int e = list.Sum();  // Noncompliant
  }
}
----


=== Compliant solution

[source,csharp]
----
void Add(List<int> list)
{
  int d = list.Sum();

  try 
  {
    int e = list.Sum();
  } 
  catch (System.OverflowException e) 
  {
    // exception handling...
  }
}
----


=== Exceptions

When the ``++Sum()++`` call is inside a ``++try-catch++`` block, no issues are reported.

[source,csharp]
----
void Add(List<int> list)
{
  unchecked 
  {
    try 
    {
      int e = list.Sum();
    } 
    catch (System.OverflowException e) 
    {
      // exception handling...
    }
  }
}
----



ifdef::env-github,rspecator-view[]

'''
== Implementation Specification
(visible only on this page)

=== Message

Refactor this code to handle "OverflowException".


'''
== Comments And Links
(visible only on this page)

=== on 13 Apr 2015, 10:44:27 Freddy Mallet wrote:
@Tamas, according to you, does this rule makes sense ? Thanks

=== on 29 Jun 2015, 14:58:19 Tamas Vajk wrote:
\[~ann.campbell.2] I've modified the description to be more specific. Also, I've changed the examples to use ``++List<int>++`` because for ``++double++``s it won't throw the ``++OverflowException++``.


\[~freddy.mallet] Yes, the rule makes sense.

=== on 30 Jun 2015, 14:45:28 Ann Campbell wrote:
Double-check my edits please [~tamas.vajk]

=== on 6 Jul 2015, 09:33:41 Tamas Vajk wrote:
\[~ann.campbell.2] Looks good.

endif::env-github,rspecator-view[]