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From: Gregory Nicholls <gnicholls@bluephoenixsolutions.com>
To: nobody@gcc.gnu.org
Cc: gcc-prs@gcc.gnu.org,
Subject: Re: preprocessor/7457: failure preprocessing ## directive
Date: Thu, 01 Aug 2002 05:46:00 -0000 [thread overview]
Message-ID: <20020801124606.21541.qmail@sources.redhat.com> (raw)
The following reply was made to PR preprocessor/7457; it has been noted by GNATS.
From: Gregory Nicholls <gnicholls@bluephoenixsolutions.com>
To: neil@gcc.gnu.org, gcc-bugs@gcc.gnu.org, gcc-prs@gcc.gnu.org,
gnicholls@bluephoenixsolutions.com, nobody@gcc.gnu.org,
gcc-gnats@gcc.gnu.org
Cc:
Subject: Re: preprocessor/7457: failure preprocessing ## directive
Date: Thu, 01 Aug 2002 08:36:29 -0400
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OK thanks,
This was some old (10yr) code that used to work and then didn't. I wondered about the concat but confess that I'm a bit vague on the pre-processor stuff.
Sorry for the trouble.
G.
neil@gcc.gnu.org wrote:
> Synopsis: failure preprocessing ## directive
>
> State-Changed-From-To: open->closed
> State-Changed-By: neil
> State-Changed-When: Wed Jul 31 15:20:59 2002
> State-Changed-Why:
> Not a bug - please understand what ## means.
>
> It means: "take the spelling of the LHS, and the spelling
> of the RHS, and concatenate the two to form a new token. If the concatenation does not form a valid token, anything goes.". You are trying to create a token
>
> "libdrv"".so"
>
> which is not a token (it's two tokens). However, if you just drop the !@#$%^& ##, then you're OK: two strings
> concatenate to become one string by the rules of C (post
> macro expansion and preprocessing).
>
> Please read a good description of what ## does.
>
> Yes, GCC is getting more picky. That's a good thing.
>
> http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=7457
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OK thanks,
<br> This was some old (10yr)
code that used to work and then didn't. I wondered about the concat but
confess that I'm a bit vague on the pre-processor stuff.
<br> Sorry for the trouble.
<br>
G.
<p>neil@gcc.gnu.org wrote:
<blockquote TYPE=CITE>Synopsis: failure preprocessing ## directive
<p>State-Changed-From-To: open->closed
<br>State-Changed-By: neil
<br>State-Changed-When: Wed Jul 31 15:20:59 2002
<br>State-Changed-Why:
<br> Not a bug - please understand what ## means.
<p> It means: "take the spelling of the LHS, and the
spelling
<br> of the RHS, and concatenate the two to form a new
token. If the concatenation does not form a valid token, anything
goes.". You are trying to create a token
<p> "libdrv"".so"
<p> which is not a token (it's two tokens). However,
if you just drop the !@#$%^& ##, then you're OK: two strings
<br> concatenate to become one string by the rules of
C (post
<br> macro expansion and preprocessing).
<p> Please read a good description of what ## does.
<p> Yes, GCC is getting more picky. That's a good
thing.
<p><a href="http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=7457">http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=7457</a></blockquote>
</html>
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next reply other threads:[~2002-08-01 12:46 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-08-01 5:46 Gregory Nicholls [this message]
-- strict thread matches above, loose matches on Subject: below --
2002-07-31 15:21 neil
2002-07-31 13:16 Zack Weinberg
2002-07-31 12:56 gnicholls
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