Why can I throw an exception after a return statement?

Asked Jan 20 '15 at 21:00

Active Jan 20 '15 at 21:06

Viewed 136 times

The C# compiler seems to not care if I have a throw statement after a return statement, even if the throw is quite clearly unreachable. The opposite is not true: the compiler can detect a return after a throw to be unreachable. Is this a compiler defect?

This compiles fine:

string MyProperty
{
    get
    {
        return "";
        throw new InvalidOperationException();
    }
}

string MyMethod()
{
    return "";
    throw new InvalidOperationException();
}

This will not compile, failing on the return statements:

string MyOtherProperty
{
    get
    {
        throw new InvalidOperationException();
        return "";
    }
}

string MyOtherMethod()
{
    throw new InvalidOperationException();
    return "";
}

EDIT: this is with .NET 4.5.1, C# version 5.0.

EDIT 2: This is the warning I see when compiling the second option (throw before return): Unreachable code detected

edited Jan 20 '15 at 21:06

asked Jan 20 '15 at 21:00

dahvyd

1

what version of the compiler? – Daniel A. White Jan 20 '15 at 21:03
1

this happens in my compiler as well: target framework .net 4.5.1, C#5, VS 2013 Professional – DLeh Jan 20 '15 at 21:05
1

Do you get compiler _warnings_ or _errors_? – D Stanley Jan 20 '15 at 21:06
1

Compiler warns when there are unreachable code in the method. In case when the `return` is unreachable it more that unreachable because not all code paths returns the value. – Hamlet Hakobyan Jan 20 '15 at 21:06
@HamletHakobyan but throwing an exception breaks the execution anyway. – Selman Genç Jan 20 '15 at 21:07
@Selman22, yes you are right. – Hamlet Hakobyan Jan 20 '15 at 21:07
2

Second implementation also compiles with warning "Unreachable code detected". Probably you may have code analysis rules in place which may be flagging warning as error. – Pankaj Kapare Jan 20 '15 at 21:07
1

Please include all actual compiler messages instead of "it fails". – CodeCaster Jan 20 '15 at 21:09
@CodeCaster Done. Regardless, that warning is not the issue here - the real question is why doesn't it detect the dead code in the first example. – dahvyd Jan 20 '15 at 21:11

Why can I throw an exception after a return statement?

0 Answers0