Re: Default constructor and const
Daniel Giaimo wrote:
On 1/21/2010 5:42 PM, Pete Becker wrote:
Daniel Giaimo wrote:
On 1/21/2010 2:58 PM, Pete Becker wrote:
Daniel Giaimo wrote:
On 1/21/2010 12:54 PM, Saeed Amrollahi wrote:
What about the -implicit- default constructor?
I ran the program under MS Visual Studio 2008. It issued a warning:
'a' : 'const' automatic data initialized with compiler generated
default
constructor produces unreliable results.
I think it is more reasonable. BTW, it is not invalid program.
The C++ standard would disagree with you. The fact that M$
Visual Studio allows it does not mean it is a valid C++
program.
In particular, the standard requires "a diagnostic". A warning can be a
diagnostic if the compiler's documentation says it is.
I'm not sure what you're saying here. Are you saying that this is a
valid C++ program? I don't have a copy of the final C++ standard on me
right now, but a quick search for a working draft online yields the
following:
If MS says that warnings are diagnostics, then Visual Studio's handling
of that code conforms to the standard. The fact that it then "allows" it
is irrelevant.
Whether Visual Studio's handling of the code conforms to the standard
is irrelevant to the question of whether the program is a valid C++
program.
That's true. But the point under discussion in this subthread is whether
"The C++ standard would disagree with you...". See above.
In order to be a valid C++ program _any_ conforming compiler
must be able to compile it.
For some unspecified value of "compile it".
The program the OP posted fails this test
as the standard allows this code to be rejected as ill-formed which,
as the OP noted, is what the Comeau compiler does.
The standard says that this code is ill-formed. If you're not happy with
getting a warning for it, then set your compiler to treat warnings as
errors. If you don't configure your compiler to do what you want, don't
complain that the compiler isn't doing what you want it to do.
--
Pete
Roundhouse Consulting, Ltd. (www.versatilecoding.com) Author of
"The Standard C++ Library Extensions: a Tutorial and Reference"
(www.petebecker.com/tr1book)
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