libc++: std::nested_exception::nested_ptr() is null or possibly indeterminate with Homebrew g++ on the Mac #113036
Description
The following code works fine, as expected, with clang++, but reports nullpointer with Homebrew g++.
#include <exception>
#include <iostream>
#include <stdexcept>
using namespace std;
#include <stdlib.h> // exit, EXIT_...
void throw_nested()
{
try {
throw runtime_error( "First exception" );
} catch( ... ) {
throw_with_nested( runtime_error( "Second exception" ) );
}
}
void check( const exception& x )
{
cout << "Checking...\n";
try {
//! rethrow_if_nested( x ); -- "libc++abi: terminating"
if( const auto p_nest = dynamic_cast<const nested_exception*>( &x ) ) {
cout << "Internal rethrowing...\n";
//! p_nest->rethrow_nested(); -- "libc++abi: terminating"
const auto x_ptr = p_nest->nested_ptr();
if( not x_ptr ) {
cout << "!Nested exception pointer is null.\n";
exit( EXIT_FAILURE ); //! libc++
}
rethrow_exception( x_ptr );
}
cout << "Not nested.\n";
} catch( ... ) {
cout << "Nested!\n";
}
cout << "Done.\n";
}
auto main() -> int
{
try {
throw_nested();
} catch( const exception& x ) {
check( x );
}
}
Results:
$ echo $OPT
-std=c++17 -pedantic-errors -Wall -Wextra
[/Users/alf/f/source/compiler-bugs]
$ clang++ ${=OPT} throw_if_nested.cpp -oa
[/Users/alf/f/source/compiler-bugs]
$ ./a
Checking...
Internal rethrowing...
Nested!
Done.
[/Users/alf/f/source/compiler-bugs]
$ g++ ${=OPT} throw_if_nested.cpp -ob
[/Users/alf/f/source/compiler-bugs]
$ ./b
Checking...
Internal rethrowing...
!Nested exception pointer is null.
Compiler versions:
- Apple clang version 16.0.0 (clang-1600.0.26.3) / Target: arm64-apple-darwin24.0.0
- g++-14 (Homebrew GCC 14.2.0) 14.2.0