Re: [boost] [fusion] Getting rid of the incomplete typeerror forvector

From: Boris Gubenko (Boris.Gubenko_at_[hidden])
Date: 2007-10-23 16:39:39

Sebastian Redl wrote:
> Boris Gubenko wrote:
>> Again, I'm not sure if a diagnostics is
>> required in this case.
> See 14.6/5:
> [...]
> The implementation is allowed to defer issuing a diagnostic until the
> function is instantiated.

This is what I suspected, but did not check. Thanks for the reference!

Boris

----- Original Message ----- 
From: "Sebastian Redl" <sebastian.redl_at_[hidden]>
To: <boost_at_[hidden]>
Sent: Tuesday, October 23, 2007 4:16 PM
Subject: Re: [boost] [fusion] Getting rid of the incomplete typeerror forvector

> Boris Gubenko wrote:
>> For the program below, in strict ansi mode, EDG Front End issues an
>> error: "incomplete type is not allowed" (and, accordingly, cxx and aC++
>> issue this error also). g++ 4.2.1 does not issue any diagnostics, even
>> when compiling '-pedantic -ansi'. Again, I'm not sure if a diagnostics is
>> required in this case.
>>
>> template <typename T>
>> struct apply {
>>   typedef T type;
>> };
>>
>> template <typename T = void>
>> struct vector;
>>
>> template <typename Iterator>
>> static typename apply<Iterator>::type
>> call(Iterator)
>> {
>>     return vector<>();
>> }
>>
> See 14.6/5:
>> No diagnostic shall be issued for a tem-
>>   plate definition for which a valid specialization  can  be  generated.
>>   If no valid specialization can be generated for a template definition,
>>   and that template is not instantiated, it is  unspecified  whether  or
>>   not  an implementation is required to issue a diagnostic.
> The implementation is allowed to defer issuing a diagnostic until the
> function is instantiated.
>
> Sebastian Redl
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