SUMMARY of g++ 2.7.0 warnings about exception handling

From: William Flett <will_at_dcs.rhbnc.ac.uk>
Date: Mon, 18 Sep 1995 14:36:46 +0100 (BST)

My original question was :

Does anyone have definitive info about warning messages produced when linking
programs compiled with g++ (v. 2.7.0) on OSF 3.2a ? For example is this info
shown in the following example correct or JUST a warning ?

platon$ g++ -g -O -L/home/staff/jon/lib -o net Net.o Node.o Data.o error.o
func.o main.o -lG -lL -lm -lad -lmac -lexc
/usr/ucb/ld:
Warning: Linking some objects which contain exception information sections
and some which do not. This may cause fatal runtime exception handling
problems (last obj encountered without exceptions was /usr/local/lib/libstdc++.a).

********* Replies (two reponses) **********

**** First reply **** from Steven Kassarjian (Steven.Kassarjian_at_Colorado.edu)

Ignore this warning message. By numerous accounts, and our own experience,
they have no noticable effect.

**** a bit more info (e.g. do they use the exception handling routines) *****

Exception handling is an area we haven't gotten deeply into yet. Our
primary work is numerical simulations, and we haven't gotten so far as
having a fortran compiler or translator running yet. (Then we'll be
having NaNs, underflows, et alia generating exceptions.)

On the other hand, I *did* compile and install GnuEmacs 19.29.1. If
you aren't familiar with GnuEmacs: one does *not* run the executable.
Instead, one runs the memory core image resulting from "temacs"
loading all the byte-compiled elisp routines and sending itself a
SIGINT and dumping core (which is then renamed to a more friendly
name, "emacs").

So, at some level exception handling does work.

Steven.Kassarjian_at_Colorado.edu

**** Second reply ****** from Sean Watson (swatson_at_ultrix6.cs.csubak.edu)

I have gotten way with ignoring the warning without ill effects so far.
I take it to mean that the OSF linker supports extentions for exception
handling but gcc does not. If you plan to use exeption handling in your c++,
you may not be able to use g++ (or at least you should pay attention to the
warning), otherwise I'm pretty sure it is safe to ignore.

*** Summary ***

It's not clear cut. It appears that if your NOT using/relying on the
exception handling routines (which we are !) your OK. There *appear* to
be no runtime errors. The big breakthrough may be when the GNU linker and
libc.so get ported (currently not supported for OSF 3.2 in the configure for
binutils 2.5.2).

One word of note, the g++ 2.7.0 was installed with the latest version of
binutils 2.5.2., which includes the GNU assembler, etc..

Hopefully this is helpful,

-Will

Computer Science Department | mail: W.Flett_at_dcs.rhbnc.ac.uk
Royal Holloway, University of London | talk: +44 1784 443428 (direct)
Egham, Surrey TW20 0EX, England | fax: +44 1784 443420
Received on Mon Sep 18 1995 - 16:30:17 NZST

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