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From: "woodard at redhat dot com" <sourceware-bugzilla@sourceware.org>
To: libabigail@sourceware.org
Subject: [Bug default/28025] New: exceptions are not checked for ABI
 compatibility.
Date: Tue, 29 Jun 2021 15:28:18 +0000
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https://sourceware.org/bugzilla/show_bug.cgi?id=3D28025

            Bug ID: 28025
           Summary: exceptions are not checked for ABI compatibility.
           Product: libabigail
           Version: unspecified
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: default
          Assignee: dodji at redhat dot com
          Reporter: woodard at redhat dot com
                CC: libabigail at sourceware dot org
  Target Milestone: ---

Libabigail doesn't inspect types which are thrown for compatibility this can
lead to ABI errors. The reason for this appears to be that it believes that=
 the
types are private and therefore not part of the exported ABI.=20

Here is an example that shows that they are.

$ for i in rtti-exception.[hC] use-rtti-excep.C;do echo --- $i;cat $i;done
--- rtti-exception.C
#include <iostream>
#include "rtti-exception.h"

extern int do_something( int num){
  std::cout << "did something\n";
  throw ex(num);
}
--- rtti-exception.h
#ifdef VER_1
class ex {
public:
  int num;
  ex( int n):num(n){}
};
#endif

#ifdef VER_2
class ex {
  float num;
public:
  ex( int n):num(n){}
};
#endif

int do_something( int num);
--- use-rtti-excep.C
#define VER_1

#include <iostream>

#include "rtti-exception.h"

int main( int argc, char **argv){
  try{
    do_something( 3);
  }
  catch( ex &excep){
    std::cout << "caught " << excep.num << std::endl;
  }
  return 0;
}

$ abidiff librttiexcep_v1.so librttiexcep_v2.so ;echo $?
0
$ abidiff rtti-v1.o rtti-v2.o ;echo $?
0
$ export SWAP_LIB_FILENAME=3Dlibswapfile
$ LD_LIBRARY_PATH=3D. ./use-rtti-excep
did something
caught 3
$ LD_AUDIT=3D./swap-libs-audit.so LD_LIBRARY_PATH=3D. ./use-rtti-excep=20
did something
caught 1077936128

It is believed that types that there is enough information in the LSDA of t=
he
object doing the throwing to be able to identify the type being thrown. It =
can
then be added to the list of types which must be compared when comparing
libraries.

--=20
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