Looking for some help with GCC 6 and bad code generation

[Zan Lynx <zlynx at acm dot org>]

I would like someone to look at this and tell me this is an already
fixed bug. Or that recent GCC patches may have fixed it. :-)

Or it would also be great to get some advice on building a reproducer
without needing to include many megabytes of proprietary code plus Boost.

I've been using Fedora 24 Alpha and of course I've somehow managed to
write some C++ code even more confusing for GCC than Firefox. Heh.

The problem is a crash when std::string tries to free memory from a
temporary std::string that was bound to a const reference.

And it only crashes when I pass -O2 or -O3 and the -fprofile-generate flags.

$ gcc -v
Using built-in specs.
COLLECT_GCC=/usr/bin/gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/6.0.0/lto-wrapper
Target: x86_64-redhat-linux
Configured with: ../configure --enable-bootstrap
--enable-languages=c,c++,objc,obj-c++,fortran,ada,go,lto --prefix=/usr
--mandir=/usr/share/man --infodir=/usr/share/info
--with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-shared
--enable-threads=posix --enable-checking=release --enable-multilib
--with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions
--enable-gnu-unique-object --enable-linker-build-id
--with-linker-hash-style=gnu --enable-plugin --enable-initfini-array
--disable-libgcj --with-isl --enable-libmpx
--enable-gnu-indirect-function --with-tune=generic --with-arch_32=i686
--build=x86_64-redhat-linux
Thread model: posix
gcc version 6.0.0 20160406 (Red Hat 6.0.0-0.20) (GCC)

I collected my findings so far into the attachment.

Thanks for reading!

-- 
                Knowledge is Power -- Power Corrupts
                        Study Hard -- Be Evil

Attachment: gcc-bug
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