Re: [Patch] Java: Add heap dump and analyze support.

[Chris Lattner <clattner at apple dot com>]

On Jan 23, 2007, at 3:42 PM, Tom Tromey wrote:

> > > > > > "Joel" == Joel Dice <dicej@mailsnare.net> writes:
>
> Joel> This is actually something I've been curious about with respect
> Joel> to libgcj. My understanding is that internal linkage is
> Joel> deprecated in C++, with anonymous namespaces as the prefered
> Joel> mechanism.  So I'm a bit suprised when I see new code that uses
> Joel> the former.  Is this just a matter of being consistent with old
> Joel> code, or is there a technical reason?
>
> libgcj is just old school.  I suppose if we were doing it over I would
> push to put all the compiler API stuff into a namespace (instead of
> having it all 'extern "C"') as well.
>
> Joel> Does g++ produce better code when using internal linkage?
>
> Not AFAIK.

G++ prior to 4.2 actually didn't mark symbols in anonymous namespaces  
as "internal", but it certainly does when symbols are marked  
'static'.  This could cause significant performance and size issues,  
depending on your code base.  In LLVM, we've resorted to marking  
classes in anonymous namespaces as attribute(hidden) to work around  
this (because you can't mark a class 'static').

See http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21581 and the related  
web of bugs.

-Chris