Re: [boost] [1.35][lexical_cast][concept check][range] Build error andwarnings with MSVC8 on Warning Level 4

From: Paul A Bristow (pbristow_at_[hidden])
Date: 2008-04-09 10:02:56

>-----Original Message-----
>From: boost-bounces_at_[hidden] 
>[mailto:boost-bounces_at_[hidden]] On Behalf Of Stephan Diederich
>Sent: 08 April 2008 20:53
>To: boost_at_[hidden]
>Subject: [boost] [1.35][lexical_cast][concept check][range] 
>Build error andwarnings with MSVC8 on Warning Level 4
>
>As we tried to update to 1.35 today, we found some warnings with MSVC
>on Warning Level 4 in:
>
>lexical_cast:
>There was a return statement after a call to throw_exception which
>causes a unreachable code warning.
>I can see no problem by just removing that return.
>see  http://svn.boost.org/trac/boost/ticket/1791

The problem code is:

throw_exception(bad_lexical_cast(typeid(Source), typeid(Target)));
return Target(); // normally never reached (throw_exception)

Is the problem that the compiler can't be confident that throw_exception won't ever return?  (For that matter, can we?)

So would it be better to *suppress the warning* ?

with a push'n'pop around this:

#if (defined _MSC_VER)
# pragma warning( push )
# pragma warning( disable : 4702 ) : unreachable code
#endif

throw_exception(bad_lexical_cast(typeid(Source), typeid(Target)));
return Target(); // normally never reached (throw_exception)

#if (defined _MSC_VER)
# pragma warning( pop )
#endif

Paul

---
Paul A Bristow
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