[Bug c++/19620] exception not caught when passing through C code

["jkanze at cheuvreux dot com" <gcc-bugzilla at gcc dot gnu dot org>]

------- Additional Comments From jkanze at cheuvreux dot com  2005-01-31 09:55 -------
Subject: Re:  exception not caught when passing through C code



> This is documented somewhere in the docs, I think.  If you mix C
> codes with C++ and exceptions are raised (through callbacks) and
> you need exceptions to smoothly travel across language
> boundaries, you need to compile the C code with -fexceptions.

The problem is that you don't always have the sources for the C
code.  Most of the time, it is in some third party library for
which you only have the .h's and the .a (or .so).  (And the
third party library has likely been compiled with Sun's cc, not
gcc.)

I'll admit that I don't understand the problem, at least on
Sparc.  There is an ABI which defines what the C stack looks
like; the C++ stack is, in fact, identical.  Walking back the
stack is trivial.  The only thing you need the tables for is for
finding destructor or handler code.  So you won't find them in
the C code which doesn't have the tables; that's no problem,
because I'm pretty sure that the C code doesn't have any
destructors, nor any exception handlers.

Is there something linked with portability which precludes this
approach.  (I know that the stack walkback code is NOT portable.
But I would have thought that this was true with or without the
tables.)

--
James Kanze        GABI Software       mailto: jkanze@cheuvreux.com
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19620