#557 Crash if compiled with -flto, -static and iostream is used

[Alex Alabuzhev]

Hi guys,

Program compiled with gcc 6.1 crashes if compiled with -flto and -static and iostream header is included.
Please see the minimal example in attachment.

It works as expected on native linux version so I assume it's mingw-specific bug.

[Mateusz Mikuła]

Testing with MSYS2 mingw-w64 gcc:
32 bit: no crash
64 bit:

(gdb) run
Starting program: C:\Users\mati865\Desktop\a.exe
[New Thread 5668.0x1898]
[New Thread 5668.0x31c]

Thread 1 received signal SIGSEGV, Segmentation fault.
0x00000000004d00f0 in __dynamic_cast ()
(gdb) bt
#0  0x00000000004d00f0 in __dynamic_cast ()
#1  0x00000000004cb565 in bool std::has_facet<std::ctype<char> >(std::locale const&) ()
#2  0x00000000004c5e94 in std::basic_ios<char, std::char_traits<char> >::_M_cache_locale(std::locale const&) ()
#3  0x00000000004c6000 in std::basic_ios<char, std::char_traits<char> >::init(std::basic_streambuf<char, std::char_traits<char> >*) ()
#4  0x00000000004c456d in std::ios_base::Init::Init() ()
#5  0x0000000000402d7f in __static_initialization_and_destruction_0 (
    __initialize_p=1, __priority=65535)
    at D:/test/msys64/mingw64/include/c++/6.1.0/iostream:74
#6  0x0000000000402fac in _GLOBAL__sub_I__Z9get_regexB5cxx11v ()
    at main.cpp:26
#7  0x0000000000428b59 in __do_global_ctors ()
    at C:/repo/mingw-w64-crt-git/src/mingw-w64/mingw-w64-crt/crt/gccmain.c:44
#8  0x0000000000428baf in __main ()
    at C:/repo/mingw-w64-crt-git/src/mingw-w64/mingw-w64-crt/crt/gccmain.c:60
#9  0x00000000004013cb in __tmainCRTStartup ()
    at C:/repo/mingw-w64-crt-git/src/mingw-w64/mingw-w64-crt/crt/crtexe.c:324
#10 0x000000000040151b in mainCRTStartup ()
    at C:/repo/mingw-w64-crt-git/src/mingw-w64/mingw-w64-crt/crt/crtexe.c:212

[niXman]

Does anyone have any ideas?

[niXman]

Fixed in 6.2.0

[Alex Alabuzhev]

Gould you provide an url please?

Example above compiled with this one 6.2.0 - https://sourceforge.net/projects/mingw-w64/files/Toolchains%20targetting%20Win64/Personal%20Builds/mingw-builds/6.2.0/threads-win32/seh/x86_64-6.2.0-release-win32-seh-rt_v5-rev1.7z/download - crashes just as before.

[niXman]

Tested using this build: https://sourceforge.net/projects/mingw-w64/files/Toolchains%20targetting%20Win32/Personal%20Builds/mingw-builds/6.2.0/threads-posix/dwarf/i686-6.2.0-release-posix-dwarf-rt_v5-rev1.7z/download

nixman@nixman-pc MSYS ~
$ g++ -v
Using built-in specs.
COLLECT_GCC=C:\mingw32-6.2.0-r1\bin\g++.exe
COLLECT_LTO_WRAPPER=C:/mingw32-6.2.0-r1/bin/../libexec/gcc/i686-w64-mingw32/6.2.0/lto-wrapper.exe
Target: i686-w64-mingw32
Configured with: ../../../src/gcc-6.2.0/configure --host=i686-w64-mingw32 --build=i686-w64-mingw32 --target=i686-w64-mingw32 --prefix=/mingw32 --with-sysroot=/c/mingw620/i686-620-posix-dwarf-rt_v5-rev1/mingw32 --enable-shared --enable-static --disable-multilib --enable-languages=c,c++,fortran,lto --enable-libstdcxx-time=yes --enable-threads=posix --enable-libgomp --enable-libatomic --enable-lto --enable-graphite --enable-checking=release --enable-fully-dynamic-string --enable-version-specific-runtime-libs --enable-libstdcxx-filesystem-ts=yes --disable-sjlj-exceptions --with-dwarf2 --disable-isl-version-check --disable-libstdcxx-pch --disable-libstdcxx-debug --enable-bootstrap --disable-rpath --disable-win32-registry --disable-nls --disable-werror --disable-symvers --with-gnu-as --with-gnu-ld --with-arch=i686 --with-tune=generic --with-libiconv --with-system-zlib --with-gmp=/c/mingw620/prerequisites/i686-w64-mingw32-static --with-mpfr=/c/mingw620/prerequisites/i686-w64-mingw32-static --with-mpc=/c/mingw620/prerequisites/i686-w64-mingw32-static --with-isl=/c/mingw620/prerequisites/i686-w64-mingw32-static --with-pkgversion='i686-posix-dwarf-rev1, Built by MinGW-W64 project' --with-bugurl=http://sourceforge.net/projects/mingw-w64 CFLAGS='-O2 -pipe -I/c/mingw620/i686-620-posix-dwarf-rt_v5-rev1/mingw32/opt/include -I/c/mingw620/prerequisites/i686-zlib-static/include -I/c/mingw620/prerequisites/i686-w64-mingw32-static/include' CXXFLAGS='-O2 -pipe -I/c/mingw620/i686-620-posix-dwarf-rt_v5-rev1/mingw32/opt/include -I/c/mingw620/prerequisites/i686-zlib-static/include -I/c/mingw620/prerequisites/i686-w64-mingw32-static/include' CPPFLAGS= LDFLAGS='-pipe -L/c/mingw620/i686-620-posix-dwarf-rt_v5-rev1/mingw32/opt/lib -L/c/mingw620/prerequisites/i686-zlib-static/lib -L/c/mingw620/prerequisites/i686-w64-mingw32-static/lib -Wl,--large-address-aware'
Thread model: posix
gcc version 6.2.0 (i686-posix-dwarf-rev1, Built by MinGW-W64 project)

nixman@nixman-pc MSYS ~
$ cat 557.cpp

#include <regex>
// if the #include <iostream> is commented - crash doesn't occur
#include <iostream>

const std::regex& get_regex()
{
        static std::regex re;

        static bool Inited = true; //false

        // this block shall never be entered, as Inited is set to true
        if (!Inited)
        {
                // if the next line is commented - crash doesn't occur
                re.assign("");

                Inited = true;
        }
        return re;
}

int main()
{
        auto z = get_regex();
        std::cout << "ping!" << std::endl;
 }

nixman@nixman-pc MSYS ~
$ g++ -std=c++11 557.cpp -o557 -static -flto && ./557
ping!

[Alex Alabuzhev]

You're testing a Win32 build, while problem is with Win64 (see the bat file in my example.zip and Mateusz's comment above).

[niXman]

Hmm... It seems this is x86_64 target bug. I`ll see.

[xnor]

Years later, 64 bit binaries produced with -flto still crash. Is there ever going to be a fix for this?

[Mateusz Mikuła]

It's binutils/GCC bug and it should be fixed there.
When using 64 bit mingw-w64 Clang with libc++ and lld it works fine, GCC 8.2 still crashes.

[xnor]

So does this bug need to be reported somewhere else?

[Mateusz Mikuła]

Yes this report belongs to Binutils or GCC bugzilla, I'm not sure which one.