Re: libstdc++/4458

[James Kanze <kanze@YAST_ASK.sourceware.cygnus.com>]

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The following reply was made to PR libstdc++/4458; it has been noted by GNATS.

From: James Kanze <kanze@YAST_ASK>
To: Martin Sebor <sebor@roguewave.com>
Cc: gcc-gnats@gcc.gnu.org, gcc-prs@gcc.gnu.org, gcc-bugs@gcc.gnu.org
Subject: Re: libstdc++/4458
Date: 28 Oct 2001 12:16:01 +0100

 Martin Sebor <sebor@roguewave.com> writes:
 
 |>  http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view&pr=4458&database=gcc
 
 |>   |>  It's not required to do so for efficiency (see 22.2.1.3.2, p5).
 
 |>   §22.2.1.1.1/1: concerning std::ctype<>::is:
 
 |>       Returns: do_is(m,c)
 
 |>   Can't be any clearer than that.  The function do_is is required by
 |>   the standard to be virtual, which means that the actual function
 |>   called (and thus the actual semantics of the function is) depend on
 |>   the dynamic type of the object.  This is, after all, the whole
 |>   point behind defining the protected virtual functions -- any other
 |>   interpretation, and having the protected interface makes sense.
 
 |>  No, you're quoting the requirement on the primary template, but your
 |>  issue (titled std::ctype<char>::is ...) is with the specialization
 |>  on char. The requirement I referred you to in 22.2.1.3.2, p5 is the
 |>  one that's relevant here. The reason for not calling the virtual
 |>  function from the ctype<char>::is() is, as I said earlier, for
 |>  efficiency.
 
 I've found it now.  It never occurred to me that the standard could
 require that a specialization have different semantics than the basic
 template.  I guess the bug is in the standard, and not in g++.
 
 I conclude that if I want to implement the iso_8859_1 locale for ctype,
 it should be sufficient to provide the correct table.  I don't need it
 for my current work, so finding time for it isn't necessarily easy, but
 if I can get around to it, do I have to do anything special to get it
 integrated into the normal g++ releases?
 
 -- 
 James Kanze                                mailto:kanze@gabi-soft.de
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