[prev in list] [next in list] [prev in thread] [next in thread] 

List:       cfe-commits
Subject:    Re: [cfe-commits] [libcxx] r157764 - in /libcxx/trunk: include/__config src/iostream.cpp
From:       Howard Hinnant <hhinnant () apple ! com>
Date:       2012-05-31 20:02:38
Message-ID: 579BA594-DA36-4CB9-A6D7-DF9EFF872D14 () apple ! com
[Download RAW message or body]

On May 31, 2012, at 3:58 PM, Chandler Carruth wrote:

> On Thu, May 31, 2012 at 12:31 PM, Howard Hinnant <hhinnant@apple.com> wrote:
> Author: hhinnant
> Date: Thu May 31 14:31:14 2012
> New Revision: 157764
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=157764&view=rev
> Log:
> Protect use of alignas against older versions of clang
> 
> Modified:
> libcxx/trunk/include/__config
> libcxx/trunk/src/iostream.cpp
> 
> Modified: libcxx/trunk/include/__config
> URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/__config?rev=157764&r1=157763&r2=157764&view=diff
>  ==============================================================================
> --- libcxx/trunk/include/__config (original)
> +++ libcxx/trunk/include/__config Thu May 31 14:31:14 2012
> @@ -145,8 +145,10 @@
> #if defined(__clang__)
> 
> #if __has_feature(cxx_alignas)
> +#  define _ALIGNAS_TYPE(x) alignas(x)
> #  define _ALIGNAS(x) alignas(x)
> #else
> +#  define _ALIGNAS_TYPE(x) __attribute__((__aligned__))
> 
> Should this be __aligned__(x) as it is here:
> 
> #  define _ALIGNAS(x) __attribute__((__aligned__(x)))
> 
> Or are you intentionally shooting for the 'maximally aligned' thing? If the latter, \
> maybe comment that this is intentional and not a typo?

It's intentional.  My first try was using _ALIGNAS, and the compiler really didn't \
like it:

../src/iostream.cpp:16:21: error: expected ')'
_ALIGNAS (__stdinbuf<char> ) static char __cin [sizeof(__stdinbuf <char>)];
                    ^
../include/__config:149:50: note: expanded from macro '_ALIGNAS'
#  define _ALIGNAS(x) __attribute__((__aligned__(x)))
                                                 ^

And so I punted by introducing _ALIGNAS_TYPE.

I can add a comment, but I'd really like to hold trunk stable for just a couple more \
hours.

Howard

_______________________________________________
cfe-commits mailing list
cfe-commits@cs.uiuc.edu
http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits


[prev in list] [next in list] [prev in thread] [next in thread]