Re: [boost] Re: Why does this work?

From: David Brownstein (David_at_[hidden])
Date: 2002-08-02 15:30:49

With MSVC6, it looks like the compiler is generating the same mangled name
for each instantiation of call_it(), as the linker complains:
fatal error LNK1179: invalid or corrupt file: duplicate comdat
"?call_it@@YAXP6AXH_at_Z@Z"

changing the return value of f2() fixes this problem... ;-) (but not
generally, I have no idea?)

David

----- Original Message -----
From: "Gennaro Prota" <gennaro_prota_at_[hidden]>
Newsgroups: gmane.comp.lib.boost.devel
To: <boost_at_[hidden]>
Sent: Friday, August 02, 2002 11:59 AM
Subject: [boost] Re: Why does this work?

> On Fri, 2 Aug 2002 21:28:05 +0300, "Peter Dimov" <pdimov_at_[hidden]>
> wrote:
>
> [...]
> >
> >Compiler bug/extension; there are compilers that diagnose it. To see that
> >it's a bug, add this:
> >
> >> int
> >> foo(int a = 1, int b = 2)
> >> { return a + b; }
> >
> >int foo2(int a = -1, int b = -2) { return a + b; }
> >
> >> ///////////////////////////////////////
> >> int
> >> main()
> >> {
> >>     typedef f_stubs<int(int a, int b)> f_stubs;
> >>
> >>     cout << f_stubs::f0(foo)    ()          << endl;
> >      cout << f_stubs::f0(foo2)    ()          << endl;
> >> }
>
>
> AFAIK this is one of the more widespread bug in C++ implementations.
> When you give two functions of the same type, like in Peter's example,
> there are compilers which fail to link and others that link but use
> the same default arguments used for the first call (in the example, 1
> and 2). Here's a simpler example:
>
>   template <typename pointerT>
>   inline void call_it(pointerT p)
>   {
>     (*p)();
>   }
>
>   void f(int i = 0) { cout << i << '\n'; }
>   void f2 (int i = 5) { cout << i << '\n'; }
>
>
>   int main ()
>   {
>     call_it(&f);
>     call_it(&f2);
>   }
>
>
>
> I wonder if there's any easy workaround.
>
>
> Genny.
>
>
>
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