Re: Backticks (`) in makefile

[LLeweLLyn Reese <llewelly at lifesupport dot shutdown dot com>]

John Love-Jensen <eljay@adobe.com> writes:

> Hi Tapu,
> 
> >The idea I have is: the standard lib in C++ will have some OS specific
> libraries and some will be architecture specific. Is it true?
> 
> I believe you are correct.
> 
> >How to identify them?
> 
> By convention, OS specific headers usually reside in the sys/... location.
> 
> Architecture specific accommodations are in the header file as
> isolated-embedded #if defined()...#endif blocks, which are usually very
> platform-centric code activated by the preprocessor.
> 
> >The next in line is, regarding ABIs .. For the compiler we'll have to define
> one ABI.. And again for standard lib in C++, we'll again have to define some C++
> ABI..At least that's what i understood..
> 
> >In which way they differ ?
> 
> I don't have an URL that describes the detailed differences between the C
> ABI (which is well established), and the C++ ABI (which has evolved from GCC
> 2.95, RedHat's 2.96, GCC 3.0, GCC 3.1, GCC 3.2 and GCC 3.3).
> 
> The C++ ABI is still somewhat of a moving target, in that GCC 3.3 is,
> hopefully, quiescent.  However, when/if a C++ ABI cross-vendor standard
> becomes available, I suspect that the GCC C++ ABI will change again, to
> accommodate the anticipated standard.

Here is a cross-vendor ABI:

http://www.codesourcery.com/cxx-abi/

gcc 3.x tries to meet that standard. 3.1.0, 3.2.0, 3.3.0 are all
    releases in which abi-breaking bugfixes had to be introduced; in
    each case gcc did not correctly implement the abi (or the abi
    changed).

However that ABI is for the core language, and does not include the
    standard library.

> 
> The C++ ABI covers things like:  exception handling, name mangling, scoped
> enumerations, inner classes/structs, calling convention, RTTI, dynamic
> casting, and probably a bazillion details with which I am unaware.

Since most programs use library facilities like std::cout, it may also
    include things such as the sizes and layouts of objects 
    passed to and from functions in libstdc++.so , and of global
    objects like std::cout. To say nothing of function names ...

> 
> (My hat is off to the unsung heroes who have tackled the C++ ABI.)

Agreed.