Re: Erroneous for-loop variable used with /Zc:forScope

From:
"Alexander Nickolov" <agnickolov@mvps.org>
Newsgroups:
microsoft.public.vc.language
Date:
Mon, 20 Aug 2007 10:26:01 -0700
Message-ID:
<#Ks7k804HHA.4436@TK2MSFTNGP03.phx.gbl>
Up to some version of VC they used the older standard for
"for" scope by default. It's changed by a compiler option:
"Force Conformance In For Loop Scope" in the Language
subitem of C/C++ options in your project (at least that's
where it is in my VC 7.1). Set that to Yes to get standard
behavior.

Note, this is a feature, not a bug :)...

--
=====================================
Alexander Nickolov
Microsoft MVP [VC], MCSD
email: agnickolov@mvps.org
MVP VC FAQ: http://vcfaq.mvps.org
=====================================

"Felipe" <felipe.m.almeida@gmail.com> wrote in message
news:1187604012.093458.202200@19g2000hsx.googlegroups.com...

Even with /Zc:forScope used, Compiling this code with Visual C++
Express 2005 tells me he is using the i from the most nested for-loop,
which is wrong! And gives an error for not having a assignment
operator. Proving is trying to use the i from the nested for-loop.
This compiles fine on Visual C++ 7.1 (2003) Professional and Visual C+
+ Express 9.0 Beta 2.

int main()
{
 struct A {
   A& operator++();
   bool operator!=(int) const;
   //A& operator=(int);
 };
 for(int i = 0; i < 10; i++)
 {
   for(A i; i != 20; ++i)
   {

   }

   i = 5;
 }
}

The error message:

subprojects\misvc\src\tnef_conversion.cpp(322) : warning C4822:
'try_convert_from_rfc2822::A::operator ++' : local class member
function does not have a body
subprojects\misvc\src\tnef_conversion.cpp(323) : warning C4822:
'try_convert_from_rfc2822::A::operator !=' : local class member
function does not have a body
subprojects\misvc\src\tnef_conversion.cpp(333) : warning C4288:
nonstandard extension used : 'i' : loop control variable declared in
the for-loop is used outside the for-loop scope; it conflicts with the
declaration in the outer scope
       subprojects\misvc\src\tnef_conversion.cpp(328) : definition of
'i' used
       subprojects\misvc\src\tnef_conversion.cpp(326) : definition of
'i' ignored
subprojects\misvc\src\tnef_conversion.cpp(333) : error C2679: binary
'=' : no operator found which takes a right-hand operand of type
'int' (or there is no acceptable conversion)

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