PSARC/2008/549 - Apache Standard C++ Library

[Garrett D'Amore]

Steve Clamage wrote:
> Regarding g++, let's take a step back.
>
> There is nothing special about the Apache library. It is an 
> implementation of the API (programming interface) described by the C++ 
> standard. *We* care about it because the two implementations of the 
> C++ standard library currently supplied with Sun Studio are each 
> missing features that some applications need. ("Why" is a long story.)
>
> If you write to the C++ standard API, it should not matter which 
> implementation you use. It will matter only if you have a deficient 
> implementation. (Missing features, non-standard behavior, or poor 
> performance, for example.)
>
> G++ comes with its own implementation of the C++ standard library that 
> is quite standard-conforming. You should be able to build the apps 
> with g++ without the Apache library. (If you have tried and found that 
> they don't work, I would be surprised, because nearly all Open Source 
> apps are developed using gcc, then tweaked to work with other compilers.)

Ah, that was not something I was aware of -- I thought GNU C++'s library 
also fell short of the mark.  Given that it's not, I'm surprised that 
Apache decided to create their own implementation instead of just 
telling folks to "use Gnu C++".   I guess we should be glad they took 
the time to make an alternate implementation available for us!

>
> I think that if we created a version of libstdcxx built with g++, 
> there would be no users. Using libstdcxx with g++ has at least the 
> same issues as using libcstdcxx with Sun Studio without direct 
> compiler support -- command lines get rather tricky.  And it's not 
> clear that libstdcxx would have significant advantages over the g++ 
> library in any case.

Okay, if other folks can corroborate your claims, then I agree we can 
safely dispense with any need for a g++ port.

>
> G++ has an additional trouble spot: the g++ ABI is not particularly 
> stable. If you build a library with one version of g++, you cannot be 
> sure it will work with another compiler version. If we provided a g++ 
> version of libstdcxx, we would have to document it as known to work 
> with only a specific version of g++.

Yeah, good point.  I'm surprised more people don't complain about this 
instability.

>
> My recommendation is not to consider further a g++ version of libstdcxx.

Concur, provided that no contradictory information to your claims surface.

    -- Garrett