Re: [BUG] try..catch does not work if compiled with clang 8.0

[Dominik Strasser <dominik dot strasser at onespin dot com>]

Hi,
I am experiencing similar problems with my software. I am using Cygwin's 
mingw g++.
The issue is very dependent on the files which are compiled, and how 
they are compiled. (-Ox, -g, ...)

My suspicion is that the problem is with ld and the merging of the 
exception region tables, but was never able to track down the issue.

However I cannot reproduce your issue on my machines. I tried:
GNU C++14 (GCC) version 7.4.0 (x86_64-pc-cygwin)
on a VM
CYGWIN_NT-6.1 xxx 2.11.2(0.329/5/3) 2018-11-08 14:34 x86_64 Cygwin
and
GNU C++14 (GCC) Version 7.4.0 (x86_64-pc-cygwin)
on my laptop
CYGWIN_NT-10.0 xxx 3.1.1(0.340/5/3) 2019-12-18 09:28 x86_64 Cygwin
with very different cygwin versions. Both of them give
./catch_test
std::exception: Error in reading no_such_file.bin

I tried my default compiler, too:
GNU C++14 (GCC) version 7.4.0 (x86_64-w64-mingw32)
No problems with this setup either.

Can you maybe post your binary so I could try it with this one.

Best regards

Dominik



Am 18.12.2019 um 16:10 schrieb Pavel Fedin:
>   Well, it turned out more complicated than i thought. Here is the reduced reproducer:
> --- cut catch_test.cpp ---
> #include <stdexcept>
> #include <iostream>
> #include <vector>
> #include <string>
> #include <fstream>
>
> void from_file(const std::string &filepath, std::vector<int8_t> &data);
>
> int main()
> {
>      try
>      {
>        std::vector<int8_t> data;
>
>        from_file("no_such_file.bin", data);
>        std::cout << "Success ???" << std::endl;
>      }
>      catch (const std::exception &e)
>      {
>        std::cout << "std::exception: " << e.what() << std::endl;
>      }
>
>      return 0;
> }
> --- cut catch_test.cpp ---
> --- cut catch_test_2.cpp ---
> #include <stdexcept>
> #include <iostream>
> #include <vector>
> #include <string>
> #include <fstream>
>
> using namespace std;
>
> template <typename T> void from_file_impl(const string &filepath, vector<T> &data)
> {
> //  data.clear();
>
>    std::ifstream ifs(filepath.c_str());
>    if (ifs.rdstate() & ifstream::failbit)
>    {
>      throw std::runtime_error("Error in reading " + filepath);
>    }
>
> /*  T buffer;
>
>    while (ifs.read(reinterpret_cast<char *>(&buffer), sizeof(T)))
>    {
>      data.push_back(buffer);
>    }*/
> }
>
> void from_file(const string &filepath, vector<int8_t> &data) { from_file_impl(filepath, data); }
> --- cut catch_test_2.cpp ---
> --- cut console log ---
> CORP+p.fedin@P-FEDIN01 /cygdrive/d/Projects/Test
> $ clang++-8 catch_test.cpp catch_test_2.cpp -g -o catch_test
>
> CORP+p.fedin@P-FEDIN01 /cygdrive/d/Projects/Test
> $ ./catch_test
>
> CORP+p.fedin@P-FEDIN01 /cygdrive/d/Projects/Test
> $ g++.exe catch_test.cpp catch_test_2.cpp -g -o catch_test
>
> CORP+p.fedin@P-FEDIN01 /cygdrive/d/Projects/Test
> $ ./catch_test
>
> CORP+p.fedin@P-FEDIN01 /cygdrive/d/Projects/Test
> $ clang++-5.0 catch_test.cpp catch_test_2.cpp -g -o catch_test
>
> CORP+p.fedin@P-FEDIN01 /cygdrive/d/Projects/Test
> $ ./catch_test
> std::exception: Error in reading no_such_file.bin
>
> CORP+p.fedin@P-FEDIN01 /cygdrive/d/Projects/Test
> $
> --- cut console log ---
>
>   So, the problem actually reproduces with both clang 8 and gcc (7.4.0 on my system). clang 5 works fine.
>
>   You could also be interested in strace (here is end of the output only, the beginning is quite long and not very interesting):
> --- cut ---
> 22301  238862 [main] catch_test 6078 seterrno_from_nt_status: /home/corinna/src/cygwin/cygwin-3.1.0/cygwin-3.1.0-1.x86_64/src/newlib-cygwin/winsup/cygwin/fhandler.cc:724 status 0xC0000034 -> windows error 2
>     75  238937 [main] catch_test 6078 geterrno_from_win_error: windows error 2 == errno 2
>     42  238979 [main] catch_test 6078 fhandler_base::open: 0xC0000034 = NtCreateFile (0x10, 0x80100000, \??\D:\Projects\Test\no_such_file.bin, io, NULL, 0x0, 0x7, 0x1, 0x4020, NULL, 0)
>     78  239057 [main] catch_test 6078 fhandler_base::open: 0 = fhandler_base::open(\??\D:\Projects\Test\no_such_file.bin, 0x108000)
>     41  239098 [main] catch_test 6078 fhandler_base::open_fs: 0 = fhandler_disk_file::open(\??\D:\Projects\Test\no_such_file.bin, 0x8000)
>     99  239197 [main] catch_test 6078 open: -1 = open(no_such_file.bin, 0x8000), errno 2
> --- Process 2620 (pid: 6078), exception 20474343 at 00007ff8c73fa388
> --- Process 2620 (pid: 6078) thread 12836 exited with status 0x20474343
> --- Process 2620 (pid: 6078) thread 3972 exited with status 0x20474343
> --- Process 2620 (pid: 6078) thread 15568 exited with status 0x20474343
> --- Process 2620 (pid: 6078) thread 5428 exited with status 0x20474343
> --- Process 2620 (pid: 6078) thread 2364 exited with status 0x20474343
> --- Process 2620 (pid: 6078) thread 16008 exited with status 0x20474343
> --- Process 2620 exited with status 0x20474343
> --- cut ---
>   So, a Windows exception is reported, then the whole thing silently quits.
>   I have an impression that it has to do with the bug i previously reported (and someone here claimed he could reproduce it)
>
> Kind regards,
> Pavel Fedin
> Senior Engineer
> Samsung Electronics Research center Russia
>
>
>> -----Original Message-----
>> From: cygwin-owner@cygwin.com [mailto:cygwin-owner@cygwin.com] On Behalf Of Brian Inglis
>> Sent: Wednesday, December 18, 2019 3:05 AM
>> To: cygwin@cygwin.com
>> Subject: Re: [BUG] try..catch does not work if compiled with clang 8.0
>>
>> On 2019-12-17 13:51, Csaba Ráduly wrote:
>>> On 17/12/2019 17:29, Brian Inglis wrote:
>>>> On 2019-12-17 02:35, Pavel Fedin wrote:
>>>>> I haven't upgraded for a while and today i finally decided to do so. After
>>>>> rebuilding by project with clang++ 8.0 i found out that try...catch construct
>>>>> doesn't work. The program just gets silently aborted.
>>>>> Switched back to old clang++ 5.0 and it works.
>>>>> Also an old bug which i reported some (a while) time ago persists: uncaught
>>>>> throw does not print anything.
>>>>> OS is Windows 10 x86/64.
>>>> It is unlikely that try/catch does not work in the general case for clang++8,
>>>> and your post has insufficient information to reproduce the problem.
>>> a.k.a. https://www.chiark.greenend.org.uk/~sgtatham/bugs.html#respect
>> Indeed!
>>> WJFFM
>>>> $ cat catcher.cpp
>>> #include <stdexcept>
>>> #include <iostream>
>>> int pitcher()
>>> {
>>>      throw std::runtime_error{"Ouch"};
>>> }
>>> int main()
>>> {
>>>      try {
>>>          return pitcher();
>>>      }
>>>      catch (std::exception const&e) {
>>>          std::cout << "Caught a " << typeid(e).name() << " - " << e.what() << '\n';
>>>          return 42;
>>>      }
>>> }
>>> $ g++ -v -Wall -Wpedantic -Wextra -g  catcher.cpp
>>> $ ./a.exe
>>> Caught a St13runtime_error - Ouch
>> The report was about clang++ 8 vs 5; tweaked source to build under 5 and 8:
>> ...
>> #include <typeinfo>
>> int pitcher()
>> {
>>      throw std::runtime_error("Ouch");
>> }
>> ...
>> but same WJFFM results:
>> $ clang++-5.0 -g -Og -Wpedantic -Wall -Wextra -o try-catch-stc{,.cpp}
>> $ ./try-catch-stc
>> Caught a St13runtime_error - Ouch
>> $ clang++-8 -g -Og -Wpedantic -Wall -Wextra -o try-catch-stc{,.cpp}
>> $ ./try-catch-stc
>> Caught a St13runtime_error - Ouch
>> --
>> Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada
>> This email may be disturbing to some readers as it contains
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-- 
Dominik Strasser       | Phone:  +49 89 99013-436
OneSpin Solutions GmbH | Fax:    +49 89 99013-100
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