[GCC] C++ program calling std::getline() crashes with certain compilation flags

[GCC] C++ program calling std::getline() crashes with certain compilation flags

[TANNHAUSER Falk]

[-- Attachment #1: Type: text/plain, Size: 1274 bytes --]

The following C++ program crashes when compiled with GCC (both 5.4 and 6.3) under Cygwin, when compiled with both an optimization level higher than -O0 (i.e. -O1, -O2 or -O3) and the C++ standard set to -std=c++nn (for any supported nn, i.e. 98, 03, 11, 14 or 17):
```
#include <iostream>
#include <string>
int main()
{
    std::string s;
    std::getline(std::cin, s);
    std::cout << "You entered \"" << s << "\".\n";
    return 0;
}
```
On the other hand, when compiled with -std=gnu++nn or -O0, the program executes normally. For details, run the attached Bash script test_getline.sh, which produces the output contained in the attached file test_getline_Cygwin.txt . No similar problem shows with GCC under Linux.
It looks similar to the problem reported in https://cygwin.com/ml/cygwin/2017-07/msg00088.html which appears to be circumvented by passing -std=gnu++11 instead of -std=c++11.
Under GDB, a faulty executable produces a message like:
```
Thread 1 "test_getline" received signal SIGABRT, Aborted.
0x00000003bf12576b in cygstdc++-6!_ZNSs7reserveEm () from /usr/bin/cygstdc++-6.dll
```
Un-mangling _ZNSs7reserveEm through c++filt gives
std::basic_string<char, std::char_traits<char>, std::allocator<char> >::reserve(unsigned long)

Falk

[-- Attachment #2: test_getline_Cygwin.txt --]
[-- Type: text/plain, Size: 3710 bytes --]

CYGWIN_NT-6.1 guam 2.8.1(0.312/5/3) 2017-07-03 14:11 x86_64 Cygwin
g++ (GCC) 6.3.0
Copyright (C) 2016 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

### -std=c++98 -O0 ###: You entered "// Let's see if it works...".
### -std=c++98 -O1 ###: ./test_getline.sh: line 18:  3744 Aborted (core dumped) ./test_getline < test_getline.cxx
### -std=c++98 -O2 ###: ./test_getline.sh: line 18:  2516 Aborted (core dumped) ./test_getline < test_getline.cxx
### -std=c++98 -O3 ###: ./test_getline.sh: line 18: 10004 Aborted (core dumped) ./test_getline < test_getline.cxx
### -std=c++03 -O0 ###: You entered "// Let's see if it works...".
### -std=c++03 -O1 ###: ./test_getline.sh: line 18: 10228 Aborted (core dumped) ./test_getline < test_getline.cxx
### -std=c++03 -O2 ###: ./test_getline.sh: line 18:  6552 Aborted (core dumped) ./test_getline < test_getline.cxx
### -std=c++03 -O3 ###: ./test_getline.sh: line 18:  9348 Aborted (core dumped) ./test_getline < test_getline.cxx
### -std=c++11 -O0 ###: You entered "// Let's see if it works...".
### -std=c++11 -O1 ###: ./test_getline.sh: line 18:  9808 Aborted (core dumped) ./test_getline < test_getline.cxx
### -std=c++11 -O2 ###: ./test_getline.sh: line 18:  9912 Aborted (core dumped) ./test_getline < test_getline.cxx
### -std=c++11 -O3 ###: ./test_getline.sh: line 18:  9904 Aborted (core dumped) ./test_getline < test_getline.cxx
### -std=c++14 -O0 ###: You entered "// Let's see if it works...".
### -std=c++14 -O1 ###: ./test_getline.sh: line 18: 10040 Aborted (core dumped) ./test_getline < test_getline.cxx
### -std=c++14 -O2 ###: ./test_getline.sh: line 18:  9380 Aborted (core dumped) ./test_getline < test_getline.cxx
### -std=c++14 -O3 ###: ./test_getline.sh: line 18:  6224 Aborted (core dumped) ./test_getline < test_getline.cxx
### -std=c++17 -O0 ###: You entered "// Let's see if it works...".
### -std=c++17 -O1 ###: ./test_getline.sh: line 18:  1476 Aborted (core dumped) ./test_getline < test_getline.cxx
### -std=c++17 -O2 ###: ./test_getline.sh: line 18:  9572 Aborted (core dumped) ./test_getline < test_getline.cxx
### -std=c++17 -O3 ###: ./test_getline.sh: line 18: 10152 Aborted (core dumped) ./test_getline < test_getline.cxx
### -std=gnu++98 -O0 ###: You entered "// Let's see if it works...".
### -std=gnu++98 -O1 ###: You entered "// Let's see if it works...".
### -std=gnu++98 -O2 ###: You entered "// Let's see if it works...".
### -std=gnu++98 -O3 ###: You entered "// Let's see if it works...".
### -std=gnu++03 -O0 ###: You entered "// Let's see if it works...".
### -std=gnu++03 -O1 ###: You entered "// Let's see if it works...".
### -std=gnu++03 -O2 ###: You entered "// Let's see if it works...".
### -std=gnu++03 -O3 ###: You entered "// Let's see if it works...".
### -std=gnu++11 -O0 ###: You entered "// Let's see if it works...".
### -std=gnu++11 -O1 ###: You entered "// Let's see if it works...".
### -std=gnu++11 -O2 ###: You entered "// Let's see if it works...".
### -std=gnu++11 -O3 ###: You entered "// Let's see if it works...".
### -std=gnu++14 -O0 ###: You entered "// Let's see if it works...".
### -std=gnu++14 -O1 ###: You entered "// Let's see if it works...".
### -std=gnu++14 -O2 ###: You entered "// Let's see if it works...".
### -std=gnu++14 -O3 ###: You entered "// Let's see if it works...".
### -std=gnu++17 -O0 ###: You entered "// Let's see if it works...".
### -std=gnu++17 -O1 ###: You entered "// Let's see if it works...".
### -std=gnu++17 -O2 ###: You entered "// Let's see if it works...".
### -std=gnu++17 -O3 ###: You entered "// Let's see if it works...".

[-- Attachment #3: test_getline.sh --]
[-- Type: application/octet-stream, Size: 587 bytes --]

cat <<EOF > test_getline.cxx
// Let's see if it works...
#include <iostream>
#include <string>
int main()
{
    std::string s;
    std::getline(std::cin, s);
    std::cout << "You entered \"" << s << "\".\n";
    return 0;
}
EOF

uname -a
g++ --version

for std in c++98 c++03 c++11 c++14 c++17 gnu++98 gnu++03 gnu++11 gnu++14 gnu++17 ; do
    for opt in 0 1 2 3 ; do
        echo -n "### -std=${std} -O${opt} ###: "
        g++ -Wall -Wextra -std=${std} -O${opt} test_getline.cxx -o test_getline &&
            ./test_getline < test_getline.cxx
    done
done 2>&1 | sed 's| \{5,\}| |g'

[-- Attachment #4: Type: text/plain, Size: 219 bytes --]


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Re: [GCC] C++ program calling std::getline() crashes with certain compilation flags

[Dan Kegel]

On Thu, Jul 6, 2017 at 6:07 AM, TANNHAUSER Falk
<Falk.Tannhauser@crf.canon.fr> wrote:
> The following C++ program crashes when compiled with GCC (both 5.4 and 6.3) under Cygwin, when compiled with both an optimization level higher than -O0 (i.e. -O1, -O2 or -O3) and the C++ standard set to -std=c++nn (for any supported nn, i.e. 98, 03, 11, 14 or 17):

Bonus points if you can reduce this testcase further, see
https://gcc.gnu.org/wiki/A_guide_to_testcase_reduction
for how to take the preprocessed output and automatically
reduce it to a much smaller file.

And by 'bonus points', I mean 'that's the first thing a
toolchain maintainer would probably do, so handing it
to them on a silver platter would help get their attention'.
- Dan

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Re: [GCC] C++ program calling std::getline() crashes with certain compilation flags

[Masamichi Hosoda]

[-- Attachment #1: Type: Text/Plain, Size: 1137 bytes --]

> The following C++ program crashes when compiled with GCC (both 5.4 and 6.3) under Cygwin, when compiled with both an optimization level higher than -O0 (i.e. -O1, -O2 or -O3) and the C++ standard set to -std=c++nn (for any supported nn, i.e. 98, 03, 11, 14 or 17):
> ```
> #include <iostream>
> #include <string>
> int main()
> {
>     std::string s;
>     std::getline(std::cin, s);
>     std::cout << "You entered \"" << s << "\".\n";
>     return 0;
> }
> ```
> On the other hand, when compiled with -std=gnu++nn or -O0, the program executes normally. For details, run the attached Bash script test_getline.sh, which produces the output contained in the attached file test_getline_Cygwin.txt . No similar problem shows with GCC under Linux.
> It looks similar to the problem reported in https://cygwin.com/ml/cygwin/2017-07/msg00088.html which appears to be circumvented by passing -std=gnu++11 instead of -std=c++11.

I've tried it with both cygwin-devel-2.8.0-1 and cygwin-devel-2.8.1-1.
With cygwin-devel-2.8.1-1, reproduced.
With cygwin-devel-2.8.0-1, there is no problem.

I've attached the script that I used and the results.

[-- Attachment #2: test_getline.sh --]
[-- Type: Application/Octet-Stream, Size: 616 bytes --]

cat <<EOF > test_getline.cxx
// Let's see if it works...
#include <iostream>
#include <string>
int main()
{
    std::string s;
    std::getline(std::cin, s);
    std::cout << "You entered \"" << s << "\".\n";
    return 0;
}
EOF

uname -a
apt-cyg show | grep "cygwin"
g++ --version

for std in c++98 c++03 c++11 c++14 c++17 gnu++98 gnu++03 gnu++11 gnu++14 gnu++17 ; do
    for opt in 0 1 2 3 ; do
        echo -n "### -std=${std} -O${opt} ###: "
        g++ -Wall -Wextra -std=${std} -O${opt} test_getline.cxx -o test_getline &&
            ./test_getline < test_getline.cxx
    done
done 2>&1 | sed 's| \{5,\}| |g'

[-- Attachment #3: test_getline_cygwin-devel-2.8.0-1.txt --]
[-- Type: Text/Plain, Size: 3227 bytes --]

CYGWIN_NT-10.0 Z87EXTREAM4 2.8.1(0.312/5/3) 2017-07-03 14:11 x86_64 Cygwin
base-cygwin                                   3.8-1
cygwin                                        2.8.1-1
cygwin-debuginfo                              2.8.1-1
cygwin-devel                                  2.8.0-1
g++ (GCC) 5.4.0
Copyright (C) 2015 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

### -std=c++98 -O0 ###: You entered "// Let's see if it works...".
### -std=c++98 -O1 ###: You entered "// Let's see if it works...".
### -std=c++98 -O2 ###: You entered "// Let's see if it works...".
### -std=c++98 -O3 ###: You entered "// Let's see if it works...".
### -std=c++03 -O0 ###: You entered "// Let's see if it works...".
### -std=c++03 -O1 ###: You entered "// Let's see if it works...".
### -std=c++03 -O2 ###: You entered "// Let's see if it works...".
### -std=c++03 -O3 ###: You entered "// Let's see if it works...".
### -std=c++11 -O0 ###: You entered "// Let's see if it works...".
### -std=c++11 -O1 ###: You entered "// Let's see if it works...".
### -std=c++11 -O2 ###: You entered "// Let's see if it works...".
### -std=c++11 -O3 ###: You entered "// Let's see if it works...".
### -std=c++14 -O0 ###: You entered "// Let's see if it works...".
### -std=c++14 -O1 ###: You entered "// Let's see if it works...".
### -std=c++14 -O2 ###: You entered "// Let's see if it works...".
### -std=c++14 -O3 ###: You entered "// Let's see if it works...".
### -std=c++17 -O0 ###: You entered "// Let's see if it works...".
### -std=c++17 -O1 ###: You entered "// Let's see if it works...".
### -std=c++17 -O2 ###: You entered "// Let's see if it works...".
### -std=c++17 -O3 ###: You entered "// Let's see if it works...".
### -std=gnu++98 -O0 ###: You entered "// Let's see if it works...".
### -std=gnu++98 -O1 ###: You entered "// Let's see if it works...".
### -std=gnu++98 -O2 ###: You entered "// Let's see if it works...".
### -std=gnu++98 -O3 ###: You entered "// Let's see if it works...".
### -std=gnu++03 -O0 ###: You entered "// Let's see if it works...".
### -std=gnu++03 -O1 ###: You entered "// Let's see if it works...".
### -std=gnu++03 -O2 ###: You entered "// Let's see if it works...".
### -std=gnu++03 -O3 ###: You entered "// Let's see if it works...".
### -std=gnu++11 -O0 ###: You entered "// Let's see if it works...".
### -std=gnu++11 -O1 ###: You entered "// Let's see if it works...".
### -std=gnu++11 -O2 ###: You entered "// Let's see if it works...".
### -std=gnu++11 -O3 ###: You entered "// Let's see if it works...".
### -std=gnu++14 -O0 ###: You entered "// Let's see if it works...".
### -std=gnu++14 -O1 ###: You entered "// Let's see if it works...".
### -std=gnu++14 -O2 ###: You entered "// Let's see if it works...".
### -std=gnu++14 -O3 ###: You entered "// Let's see if it works...".
### -std=gnu++17 -O0 ###: You entered "// Let's see if it works...".
### -std=gnu++17 -O1 ###: You entered "// Let's see if it works...".
### -std=gnu++17 -O2 ###: You entered "// Let's see if it works...".
### -std=gnu++17 -O3 ###: You entered "// Let's see if it works...".

[-- Attachment #4: test_getline_cygwin-devel-2.8.1-1.txt --]
[-- Type: Text/Plain, Size: 3933 bytes --]

CYGWIN_NT-10.0 Z87EXTREAM4 2.8.1(0.312/5/3) 2017-07-03 14:11 x86_64 Cygwin
base-cygwin                                   3.8-1
cygwin                                        2.8.1-1
cygwin-debuginfo                              2.8.1-1
cygwin-devel                                  2.8.1-1
g++ (GCC) 5.4.0
Copyright (C) 2015 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

### -std=c++98 -O0 ###: You entered "// Let's see if it works...".
### -std=c++98 -O1 ###: ./test_getline.sh: line 19: 20748 Aborted (core dumped) ./test_getline < test_getline.cxx
### -std=c++98 -O2 ###: ./test_getline.sh: line 19: 25148 Aborted (core dumped) ./test_getline < test_getline.cxx
### -std=c++98 -O3 ###: ./test_getline.sh: line 19:  8540 Aborted (core dumped) ./test_getline < test_getline.cxx
### -std=c++03 -O0 ###: You entered "// Let's see if it works...".
### -std=c++03 -O1 ###: ./test_getline.sh: line 19: 16156 Aborted (core dumped) ./test_getline < test_getline.cxx
### -std=c++03 -O2 ###: ./test_getline.sh: line 19: 12172 Aborted (core dumped) ./test_getline < test_getline.cxx
### -std=c++03 -O3 ###: ./test_getline.sh: line 19:   160 Aborted (core dumped) ./test_getline < test_getline.cxx
### -std=c++11 -O0 ###: You entered "// Let's see if it works...".
### -std=c++11 -O1 ###: ./test_getline.sh: line 19: 24840 Aborted (core dumped) ./test_getline < test_getline.cxx
### -std=c++11 -O2 ###: ./test_getline.sh: line 19: 12008 Aborted (core dumped) ./test_getline < test_getline.cxx
### -std=c++11 -O3 ###: ./test_getline.sh: line 19:  8140 Aborted (core dumped) ./test_getline < test_getline.cxx
### -std=c++14 -O0 ###: You entered "// Let's see if it works...".
### -std=c++14 -O1 ###: ./test_getline.sh: line 19:  7376 Aborted (core dumped) ./test_getline < test_getline.cxx
### -std=c++14 -O2 ###: ./test_getline.sh: line 19: 18080 Aborted (core dumped) ./test_getline < test_getline.cxx
### -std=c++14 -O3 ###: ./test_getline.sh: line 19: 22692 Aborted (core dumped) ./test_getline < test_getline.cxx
### -std=c++17 -O0 ###: You entered "// Let's see if it works...".
### -std=c++17 -O1 ###: ./test_getline.sh: line 19:  5796 Aborted (core dumped) ./test_getline < test_getline.cxx
### -std=c++17 -O2 ###: ./test_getline.sh: line 19: 24008 Aborted (core dumped) ./test_getline < test_getline.cxx
### -std=c++17 -O3 ###: ./test_getline.sh: line 19:  2844 Aborted (core dumped) ./test_getline < test_getline.cxx
### -std=gnu++98 -O0 ###: You entered "// Let's see if it works...".
### -std=gnu++98 -O1 ###: You entered "// Let's see if it works...".
### -std=gnu++98 -O2 ###: You entered "// Let's see if it works...".
### -std=gnu++98 -O3 ###: You entered "// Let's see if it works...".
### -std=gnu++03 -O0 ###: You entered "// Let's see if it works...".
### -std=gnu++03 -O1 ###: You entered "// Let's see if it works...".
### -std=gnu++03 -O2 ###: You entered "// Let's see if it works...".
### -std=gnu++03 -O3 ###: You entered "// Let's see if it works...".
### -std=gnu++11 -O0 ###: You entered "// Let's see if it works...".
### -std=gnu++11 -O1 ###: You entered "// Let's see if it works...".
### -std=gnu++11 -O2 ###: You entered "// Let's see if it works...".
### -std=gnu++11 -O3 ###: You entered "// Let's see if it works...".
### -std=gnu++14 -O0 ###: You entered "// Let's see if it works...".
### -std=gnu++14 -O1 ###: You entered "// Let's see if it works...".
### -std=gnu++14 -O2 ###: You entered "// Let's see if it works...".
### -std=gnu++14 -O3 ###: You entered "// Let's see if it works...".
### -std=gnu++17 -O0 ###: You entered "// Let's see if it works...".
### -std=gnu++17 -O1 ###: You entered "// Let's see if it works...".
### -std=gnu++17 -O2 ###: You entered "// Let's see if it works...".
### -std=gnu++17 -O3 ###: You entered "// Let's see if it works...".


[-- Attachment #5: Type: text/plain, Size: 219 bytes --]


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[GCC] C++ program calling std::getline() crashes with certain compilation flags

[TANNHAUSER Falk]

[-- Attachment #1: Type: text/plain, Size: 607 bytes --]


> Bonus points if you can reduce this testcase further, see
> https://gcc.gnu.org/wiki/A_guide_to_testcase_reduction
> for how to take the preprocessed output and automatically
> reduce it to a much smaller file.

I attach the output of
  ```
  creduce checki.sh test_getline.i
  ```
where checki.sh is attached too and test_getline.i was obtained trough
  ```
  g++ -w -std=c++98 -O0 -E -P test_getline.cxx > test_getline.i
  ```
Note that passing -O1 instead of -O0 doesn't change the pre-processed output,
while replacing -std=c++98 by -std=gnu++98 triggers substantial changes.

Falk

[-- Attachment #2: test_getline.i --]
[-- Type: application/octet-stream, Size: 928 bytes --]

namespace std { template < typename > class allocator; template < class > struct char_traits; template < typename b, typename = char_traits< b >, typename = allocator< b > > class basic_string; typedef basic_string< char > c; template < typename b, typename = char_traits< b > > class basic_istream; typedef basic_istream< char > d; template < typename > class allocator {}; template < typename b, typename, typename e > class basic_string {   struct _Rep {     b *_M_refdata();   };   struct f {     f(b *g, e) : h(g) {}     b *h;   } i;   _Rep &j() {}  public:   basic_string() : i(j()._M_refdata(), e()) {} }; template < typename b, typename k, typename e > basic_istream< b, k > &getline(basic_istream< b, k > &,                                basic_string< b, k, e > &); class ios_base { public:   class Init {   public:     Init();   }; }; extern d cin; ios_base::Init l; }
 main() {   std::c a;   getline(std::cin, a); }

[-- Attachment #3: checki.sh --]
[-- Type: application/octet-stream, Size: 245 bytes --]

g++ -w -std=c++98 -O0 test_getline.i -o test_getline && echo a | ./test_getline
if ! test "$?" = "0" ; then exit 1 ; fi
g++ -w -std=c++98 -O1 test_getline.i -o test_getline && echo a | ./test_getline
if test "$?" = "0" ; then exit 1 ; fi
exit 0

[-- Attachment #4: Type: text/plain, Size: 219 bytes --]


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RE: [GCC] C++ program calling std::getline() crashes with certain compilation flags

[TANNHAUSER Falk]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain; charset="utf-8", Size: 436 bytes --]

This problem goes away when updating Cygwin x86_64 from 2.8.1 to 2.8.2 ; same for this one:
https://cygwin.com/ml/cygwin/2017-07/msg00088.html "g++ std::map initializing raises segmentation fault."

Falk
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