Paolo Carlini wrote:
... I see this comment in except.c:do_begin_catch:
/* Declare void* __cxa_begin_catch (void *). */
Instead, in libstdc++/libsup++/unwind-cxx.h:
extern "C" void *__cxa_begin_catch (void *) throw();
So, who is right? Note, the symbol is exported, I'm not suer which headroom for
changes we do have. I would appreciate if Mark could also have a look (as a C++
ABI issue)...
This is not an ABI issue; the presence of absence of an
exception-specifier does not affect the ABI. The ABI document:
http://www.codesourcery.com/public/cxx-abi/abi-eh.html
doesn't have a throw-specifier on that routine, so one could argue that
this means the declaration shouldn't have one. However, I think that's
specious; it was intended that these helper functions could even be
implemented in C, without exceptions.
In general, of course, it's better for optimization purposes if
functions have "throw()" on them -- provided that all functions they
call *also* have that marker. In that case, the compiler can elide the
exception tables. The duality here is that if any of the callees do
*not* have the marker, then the caller must *add* code to catch the
exceptions thrown by callees and raise std::unexpected.
So, you want to work bottom-up, putting "throw()" on the leaf functions,
and then on callers that call only "throw()" functions and so forth.
--
Mark Mitchell
CodeSourcery
[EMAIL PROTECTED]
(650) 331-3385 x713
