Re: Inadequate error message C2228
Vladimir Grigoriev wrote:
"Cezary H. Noweta" <chncc@noemail.noemail> wrote in message
news:ugTNvN$nIHA.3376@TK2MSFTNGP05.phx.gbl...
Yes, but (B(a)) still can be (and really it is) optimized to B(a),
Sorry, but this completely misses the point. Adding additional brackets is
purely syntactic in order to force the compiler to not parse anything as a
function declaration. Other than that, when taken alone, you can add any
number of parentheses to an expression.
thus copy ctor will be omitted. In ((void)0, B(A)) copy ctor could be
omitted too (there is no sequence point after a whole expression), but
hopefully compilers are not happy to do this.
Of course, these deductions are fallacious, too, since they depend on false
assumptions.
It is interesting to note that different compilers behave differently.
Visual C++ 2003 EE omits copy ctor for the statement
B b( ( B( a ) ) );
while BCB 5.0 calls copy ctor as it is specified explicitly.
You can not explicitly specify that it should call the copy constructor. As
I explained in the other thread already it is up to the implementer to
elide copy constructors if they can determine that the copy is not needed.
Yes, it's a bit confusing, but neither BCB nor VC are 'wrong'.
Uli
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