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From: "david.cortes.rivera at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug c++/102237] New: longjmp leaks catched std::runtime_error
Date: Wed, 08 Sep 2021 02:19:21 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D102237

            Bug ID: 102237
           Summary: longjmp leaks catched std::runtime_error
           Product: gcc
           Version: 10.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: david.cortes.rivera at gmail dot com
  Target Milestone: ---

Created attachment 51425
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=3D51425&action=3Dedit
ii_file

I am experiencing a memory leak when using long jumps from a catch block in
which the jump takes to a different function. Basically, the exception obje=
cts
are not getting destructed.

>>From what I gather from this SO question:
https://stackoverflow.com/questions/69092014/c-will-an-stdruntime-error-obj=
ect-leak-in-a-longjmp

calling something like "catch(std::exception &e) {longjmp(jump_buffer, 1);}"
should be allowed by the standard, and the exception should be destructed a=
long
the way.

For example, the following code ***works as expected***:
-------
#include <stdexcept>
#include <stdio.h>
#include <setjmp.h>

void my_fun()
{
    jmp_buf jump_buffer;
    if (setjmp(jump_buffer))
        return;

    try {
        std::string message;
        message.resize(100);
        snprintf(&message[0], 100, "error code %d\n", 3);
        throw std::runtime_error(message);
    }

    catch (std::runtime_error &e) {
        longjmp(jump_buffer, 1);
    }
}

int main()
{
    for (int ix =3D 0; ix < 100000; ix++)
        void my_fun();
    return 0;
}
-------

...

But ***if I switch the jump buffer to be outside of the function***, it will
now start leaking memory at each call:
-------
#include <stdexcept>
#include <stdio.h>
#include <setjmp.h>

jmp_buf jump_buffer;
void my_fun()
{
    try {
        std::string message;
        message.resize(100);
        snprintf(&message[0], 100, "error code %d\n", 3);
        throw std::runtime_error(message);
    }

    catch (std::runtime_error &e) {
        longjmp(jump_buffer, 1);
    }
}

void call_myfun()
{
    if (setjmp(jump_buffer))
        return;
    my_fun();
}

int main()
{
    for (int ix =3D 0; ix < 100000; ix++)
        call_myfun();
    return 0;
}
-------


Setup info:
- AMD Ryzen 7 2700.
- Debian linux (sid)
- gcc --version: gcc (Debian 10.3.0-9) 10.3.0

The source file is compiled with the default options (g++ file.cpp). The le=
ak
is detected by valgrind-3.16.1.

Attached is the .ii file.=