Fix inconsistent behavior in basic_ostream::seekp () and basic_istream::seekg ()

[Howard Hinnant]

On Oct 21, 2013, at 2:29 PM, Marshall Clow <mclow.lists at gmail.com> wrote:

> Basically, each of these have two methods:
> 
> 	basic_ostream<charT,traits>& seekp(pos_type pos);
> 	basic_ostream<charT,traits>& seekp(off_type off, ios_base::seekdir dir);
> 
> and one sets the failure bit of the stream on failure, and the other does not.
> [ Note that the standard requires us to set the failure bit on the first call, and is silent on the second. I have opened an LWG issue to resolve this. ]
> Make the second version set the failbit, and add tests.
> 
> Also, the ostream calls were lacking a sentry object.
> 
> For basic_istream, there were two calls, as well:
> 
> 	basic_istream<charT,traits>& seekg(pos_type pos);
> 	basic_istream<charT,traits>& seekg(off_type off, ios_base::seekdir dir);
> 
> and they are both specified to set the failbit on failure, and only the first one did.
> Fix that, and add a test to be sure.
> 
> 
> -- Marshall
> 
> Marshall Clow     Idio Software   <mailto:mclow.lists at gmail.com>
> 
> A.D. 1517: Martin Luther nails his 95 Theses to the church door and is promptly moderated down to (-1, Flamebait).
>        -- Yu Suzuki
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This looks pretty good to me.  My only complaint is:

+    if ( __s && !this->fail())

(two places in <ostream>).

The "&& !this->fail()" becomes redundant with the addition of __s.  So this should be:

+    if ( __s )

Thanks!

Howard