Re: Question about compiler bug: Value-initialization in new-expression

From:
"Niels Dekker - no return address" <unknown@this.is.invalid>
Newsgroups:
microsoft.public.vc.language
Date:
Mon, 14 May 2007 22:28:05 +0200
Message-ID:
<Okk4eZmlHHA.2272@TK2MSFTNGP02.phx.gbl>

According to the Feedback page, the status of #100744
is "Closed (Won't Fix)". Does that really mean that
this bug won't get fixed at all???


Carl Daniel [VC++ MVP] replied:

It means it won't get fixed in Orcas.


Thank you for your quick response. But unfortunately the workaround you
suggested doesn't compile. (See below.)

[Quoting myself again]

the bug was reported in 2005 already, by Pavel: Feedback ID 100744,
"Value-initialization in new-expression".
https://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=100744

The example has a struct that looks very much like mine:

 struct A {
   std::string s;
   int i;
 };

....

Note that other attempts to value-initialize the struct fail as well:

 #include <cassert>

 class B {
   A m_a;
 public:
   B(): m_a() {
     assert(m_a.i == 0); // Assertion fails!
   }
 };


Carl Daniel [VC++ MVP] wrote:

In practice, it's an easy bug to work around, since you can simply
write your constructor as:

 class B {
   A m_a;
 public:
   B(): m_a(0) {
     assert(m_a.i == 0); // Assertion fails!
   }
 };


I'm sorry to say your workaround does not compile, as the compiler says:
error C2664: 'A::A(const A &)' : cannot convert parameter 1 from 'int'
to 'const A &' (And this time the compiler is right, of course.)

Kind regards, Niels

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