[Bug c++/85091] Compiler generates different code depending on whether -Wnonnull -Woverloaded-virtual given or not

[vz-gcc at zeitlins dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85091

--- Comment #25 from Vadim Zeitlin <vz-gcc at zeitlins dot org> ---
(In reply to Martin Liška from comment #24)
> > Please let me know if I can do anything else.
> 
> Can you please attach full diff?

Sorry, diff between what and what?

> Am I correct that your native compiler is on x86_64?

Yes.

> Please attach output of --verbose.

Here it is:

% g++-7 --verbose -S -std=c++17 -O2 -Wnonnull -Woverloaded-virtual
gcc-7.3-x86_64-linux.cpp -o warn.s
Using built-in specs.
COLLECT_GCC=g++-7
OFFLOAD_TARGET_NAMES=nvptx-none
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Debian 7.3.0-12'
--with-bugurl=file:///usr/share/doc/gcc-7/README.Bugs
--enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++ --prefix=/usr
--with-gcc-major-version-only --program-suffix=-7
--program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu
--enable-libstdcxx-debug --enable-libstdcxx-time=yes
--with-default-libstdcxx-abi=new --enable-gnu-unique-object
--disable-vtable-verify --enable-libmpx --enable-plugin --enable-default-pie
--with-system-zlib --with-target-system-zlib --enable-objc-gc=auto
--enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64
--with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic
--enable-offload-targets=nvptx-none --without-cuda-driver
--enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu
--target=x86_64-linux-gnu
Thread model: posix
gcc version 7.3.0 (Debian 7.3.0-12)
COLLECT_GCC_OPTIONS='-v' '-S' '-std=c++1z' '-O2' '-Wnonnull'
'-Woverloaded-virtual' '-o' 'warn.s' '-shared-libgcc' '-mtune=generic'
'-march=x86-64'
 /usr/lib/gcc/x86_64-linux-gnu/7/cc1plus -quiet -v -imultiarch x86_64-linux-gnu
-D_GNU_SOURCE 14881.cpp -quiet -dumpbase 14881.cpp -mtune=generic -march=x86-64
-auxbase-strip warn.s -O2 -Wnonnull -Woverloaded-virtual -std=c++1z -version -o
warn.s
GNU C++14 (Debian 7.3.0-12) version 7.3.0 (x86_64-linux-gnu)
        compiled by GNU C version 7.3.0, GMP version 6.1.2, MPFR version 4.0.1,
MPC version 1.1.0, isl version isl-0.19-GMP

GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
ignoring duplicate directory "/usr/include/x86_64-linux-gnu/c++/7"
ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu"
ignoring nonexistent directory
"/usr/lib/gcc/x86_64-linux-gnu/7/../../../../x86_64-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/include/c++/7
 /usr/include/x86_64-linux-gnu/c++/7
 /usr/include/c++/7/backward
 /usr/lib/gcc/x86_64-linux-gnu/7/include
 /usr/local/include
 /usr/lib/gcc/x86_64-linux-gnu/7/include-fixed
 /usr/include/x86_64-linux-gnu
 /usr/include
End of search list.
GNU C++14 (Debian 7.3.0-12) version 7.3.0 (x86_64-linux-gnu)
        compiled by GNU C version 7.3.0, GMP version 6.1.2, MPFR version 4.0.1,
MPC version 1.1.0, isl version isl-0.19-GMP

GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 6054b92b0b90c9db1f26de9c9b53361c
COMPILER_PATH=/usr/lib/gcc/x86_64-linux-gnu/7/:/usr/lib/gcc/x86_64-linux-gnu/7/:/usr/lib/gcc/x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/7/:/usr/lib/gcc/x86_64-linux-gnu/
LIBRARY_PATH=/usr/lib/gcc/x86_64-linux-gnu/7/:/usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/7/../../../../lib/:/lib/x86_64-linux-gnu/:/lib/../lib/:/usr/lib/x86_64-linux-gnu/:/usr/lib/../lib/:/usr/lib/gcc/x86_64-linux-gnu/7/../../../:/lib/:/usr/lib/
COLLECT_GCC_OPTIONS='-v' '-S' '-std=c++1z' '-O2' '-Wnonnull'
'-Woverloaded-virtual' '-o' 'warn.s' '-shared-libgcc' '-mtune=generic'
'-march=x86-64'