[Bug c++/67711] New: Memory corruption when reassigning value to initializer_list

[Bug c++/67711] New: Memory corruption when reassigning value to initializer_list

[7.janis at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67711

            Bug ID: 67711
           Summary: Memory corruption when reassigning value to
                    initializer_list
           Product: gcc
           Version: 4.8.5
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: 7.janis at gmail dot com
  Target Milestone: ---

Created attachment 36386
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=36386&action=edit
preprocessed file

according to gdb, variables "started" and "needed" use the same memory address
after the second assignment to "needed" (see test case source code below) 

compiled with:
        g++ -v -save-temps -std=c++11 -Wall -Wextra -O0 -o compiler_bug
compiler_bug.cpp 
output: 
        6304208
expected output:
        1


gcc version: 4.8.5


test case code:

#include <iostream>
#include <initializer_list>
#include <string>
#include <vector>
using namespace std;

int main()
{
        int required = 1;
        initializer_list<int> needed = {0, 1, 2};
        needed = {required};
        vector<bool> started = {true};
        for (int item : needed) {
                cout << item <<endl;
        }
        return 0;
}


compilation output:

g++ -v -save-temps -std=c++11 -Wall -Wextra -O0 -o compiler_bug
compiler_bug.cpp 
Using built-in specs.
COLLECT_GCC=/usr/x86_64-pc-linux-gnu/gcc-bin/4.8.5/g++
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-pc-linux-gnu/4.8.5/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /var/tmp/portage/sys-devel/gcc-4.8.5/work/gcc-4.8.5/configure
--host=x86_64-pc-linux-gnu --build=x86_64-pc-linux-gnu --prefix=/usr
--bindir=/usr/x86_64-pc-linux-gnu/gcc-bin/4.8.5
--includedir=/usr/lib/gcc/x86_64-pc-linux-gnu/4.8.5/include
--datadir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.8.5
--mandir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.8.5/man
--infodir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.8.5/info
--with-gxx-include-dir=/usr/lib/gcc/x86_64-pc-linux-gnu/4.8.5/include/g++-v4
--with-python-dir=/share/gcc-data/x86_64-pc-linux-gnu/4.8.5/python
--enable-languages=c,c++ --enable-obsolete --enable-secureplt --disable-werror
--with-system-zlib --enable-nls --without-included-gettext
--enable-checking=release --with-bugurl=https://bugs.gentoo.org/
--with-pkgversion='Gentoo 4.8.5 p1.3, pie-0.6.2' --enable-libstdcxx-time
--enable-shared --enable-threads=posix --enable-__cxa_atexit
--enable-clocale=gnu --enable-multilib --with-multilib-list=m32,m64
--disable-altivec --disable-fixed-point --enable-targets=all --disable-libgcj
--enable-libgomp --disable-libmudflap --disable-libssp --disable-libquadmath
--enable-lto --without-cloog --disable-libsanitizer
Thread model: posix
gcc version 4.8.5 (Gentoo 4.8.5 p1.3, pie-0.6.2)
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-std=c++11' '-Wall' '-Wextra' '-O0'
'-o' 'compiler_bug' '-shared-libgcc' '-mtune=generic' '-march=x86-64'
 /usr/libexec/gcc/x86_64-pc-linux-gnu/4.8.5/cc1plus -E -quiet -v -D_GNU_SOURCE
compiler_bug.cpp -mtune=generic -march=x86-64 -std=c++11 -Wall -Wextra -O0
-fpch-preprocess -fstack-protector -o compiler_bug.ii
ignoring nonexistent directory
"/usr/lib/gcc/x86_64-pc-linux-gnu/4.8.5/../../../../x86_64-pc-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/lib/gcc/x86_64-pc-linux-gnu/4.8.5/include/g++-v4
 /usr/lib/gcc/x86_64-pc-linux-gnu/4.8.5/include/g++-v4/x86_64-pc-linux-gnu
 /usr/lib/gcc/x86_64-pc-linux-gnu/4.8.5/include/g++-v4/backward
 /usr/lib/gcc/x86_64-pc-linux-gnu/4.8.5/include
 /usr/local/include
 /usr/lib/gcc/x86_64-pc-linux-gnu/4.8.5/include-fixed
 /usr/include
End of search list.
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-std=c++11' '-Wall' '-Wextra' '-O0'
'-o' 'compiler_bug' '-shared-libgcc' '-mtune=generic' '-march=x86-64'
 /usr/libexec/gcc/x86_64-pc-linux-gnu/4.8.5/cc1plus -fpreprocessed
compiler_bug.ii -quiet -dumpbase compiler_bug.cpp -mtune=generic -march=x86-64
-auxbase compiler_bug -O0 -Wall -Wextra -std=c++11 -version -fstack-protector
-o compiler_bug.s
GNU C++ (Gentoo 4.8.5 p1.3, pie-0.6.2) version 4.8.5 (x86_64-pc-linux-gnu)
        compiled by GNU C version 4.8.5, GMP version 5.1.3, MPFR version 3.1.2,
MPC version 1.0.1
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
GNU C++ (Gentoo 4.8.5 p1.3, pie-0.6.2) version 4.8.5 (x86_64-pc-linux-gnu)
        compiled by GNU C version 4.8.5, GMP version 5.1.3, MPFR version 3.1.2,
MPC version 1.0.1
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 60cb6a3ad386bcc89202209cc17d3533
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-std=c++11' '-Wall' '-Wextra' '-O0'
'-o' 'compiler_bug' '-shared-libgcc' '-mtune=generic' '-march=x86-64'
 /usr/lib/gcc/x86_64-pc-linux-gnu/4.8.5/../../../../x86_64-pc-linux-gnu/bin/as
-v --64 -o compiler_bug.o compiler_bug.s
GNU assembler version 2.24 (x86_64-pc-linux-gnu) using BFD version (Gentoo 2.24
p1.4) 2.24
COMPILER_PATH=/usr/libexec/gcc/x86_64-pc-linux-gnu/4.8.5/:/usr/libexec/gcc/x86_64-pc-linux-gnu/4.8.5/:/usr/libexec/gcc/x86_64-pc-linux-gnu/:/usr/lib/gcc/x86_64-pc-linux-gnu/4.8.5/:/usr/lib/gcc/x86_64-pc-linux-gnu/:/usr/lib/gcc/x86_64-pc-linux-gnu/4.8.5/../../../../x86_64-pc-linux-gnu/bin/
LIBRARY_PATH=/usr/lib/gcc/x86_64-pc-linux-gnu/4.8.5/:/usr/lib/gcc/x86_64-pc-linux-gnu/4.8.5/../../../../lib64/:/lib/../lib64/:/usr/lib/../lib64/:/usr/lib/gcc/x86_64-pc-linux-gnu/4.8.5/../../../../x86_64-pc-linux-gnu/lib/:/usr/lib/gcc/x86_64-pc-linux-gnu/4.8.5/../../../:/lib/:/usr/lib/
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-std=c++11' '-Wall' '-Wextra' '-O0'
'-o' 'compiler_bug' '-shared-libgcc' '-mtune=generic' '-march=x86-64'
 /usr/libexec/gcc/x86_64-pc-linux-gnu/4.8.5/collect2 --eh-frame-hdr -m
elf_x86_64 -dynamic-linker /lib64/ld-linux-x86-64.so.2 -o compiler_bug
/usr/lib/gcc/x86_64-pc-linux-gnu/4.8.5/../../../../lib64/crt1.o
/usr/lib/gcc/x86_64-pc-linux-gnu/4.8.5/../../../../lib64/crti.o
/usr/lib/gcc/x86_64-pc-linux-gnu/4.8.5/crtbegin.o
-L/usr/lib/gcc/x86_64-pc-linux-gnu/4.8.5
-L/usr/lib/gcc/x86_64-pc-linux-gnu/4.8.5/../../../../lib64 -L/lib/../lib64
-L/usr/lib/../lib64
-L/usr/lib/gcc/x86_64-pc-linux-gnu/4.8.5/../../../../x86_64-pc-linux-gnu/lib
-L/usr/lib/gcc/x86_64-pc-linux-gnu/4.8.5/../../.. compiler_bug.o -lstdc++ -lm
-lgcc_s -lgcc -lc -lgcc_s -lgcc /usr/lib/gcc/x86_64-pc-linux-gnu/4.8.5/crtend.o
/usr/lib/gcc/x86_64-pc-linux-gnu/4.8.5/../../../../lib64/crtn.o

[Bug c++/67711] Memory corruption when reassigning value to initializer_list

[trippels at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67711

Markus Trippelsdorf <trippels at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2015-09-24
                 CC|                            |trippels at gcc dot gnu.org
     Ever confirmed|0                           |1
      Known to fail|                            |4.9.3, 5.2.0, 6.0

--- Comment #1 from Markus Trippelsdorf <trippels at gcc dot gnu.org> ---
Hmm,

markus@x4 tmp % cat compil.cpp
#include <initializer_list>

int main()
{
        int required = 1;
        std::initializer_list<int> needed;
        needed = {required};
        if (*begin(needed)!=1)
                __builtin_abort();
}

markus@x4 tmp % g++ -O2 -std=c++11 compil.cpp && ./a.out
[1]    24721 abort      ./a.out

Lifetime of std::initializer_list can be tricky, but I think the testcase above
is valid.