Re: GNAT and GCC compatability.

[Florian Weimer <fw@deneb.cygnus.argh.org>]

Preben Randhol <randhol@pvv.org> writes:

> "Larry Stanbery" <stanbery@foo.earthling.net> writes:
> 
> | I searched DejaNews for info on this, but found none...
> | 
> | I've currently got GNAT 3.11p, and realized I had a need to compile some C++
> | code I obtained.  I checked, and, of course, GNAT doesn't install g++ and
> | the associated header files, etc.  So, I wanted to know if there are things
> | I need to watch out for -- do I need a specific version of gcc?  Things like
> | that.
> 
> It depends. What kind of system do you have ? Linux, Solaris, DEC
> ... which distribution. 

Additional questions are: Are you going to use the GNAT C++ interface?
Has the C++ code already been compiled successfully with a GNU compiler?
Which standard libraries are used?  Is it ISO C++?  (Compiler vendors
often provide different implementations of for-scoping rules, templates,
exception and RTTI, more or less ignoring the standard.  C++ is not Ada.)

Both C++ and the GNU implementation changed a lot in the past few years.
If you know that a certain GCC version compiles the code correctly,
you should probably use that one.  Otherwise, you might want to try
several GCC versions: 2.7.2.3, 2.8.1 and 2.95.1 are the three latest
major releases.

Note that you shouldn't build the C++ compiler from a GNAT-patched
source tree, because some portions of the GCC backend are also changed
and the resulting C++ compiler, which would include these changes as
well, hasn't been tested.

> Some C++ programs uses STL templates ++ then you need either the
> latest gcc 2.95 (I think) or egcs.

There isn't an egcs project anymore.  The egcs development is the current
GCC tree (`GNU Compiler Collection'), GCC 2.95 and 2.95.1 are releases
based on this development tree (i.e., the former egcs tree).