On Tue, Mar 27, 2018 at 5:12 PM, Vadim Zeitlin <vz-gcc@xxxxxxxxxxxx> wrote: > On Tue, 27 Mar 2018 16:48:39 +0200 Mathieu Malaterre <malat@xxxxxxxxxx> wrote: > > MM> Using a mixed stretch with g++-mingw-w64-i686/sid here is what I see: > > Hi Mathieu and thanks for testing this! > > MM> $ i686-w64-mingw32-g++ -c -std=c++17 -O2 -Wnonnull -Woverloaded-virtual -v 16795.cpp -o warn.o > [...] > > This is indeed exactly the same thing as I see too, including the warning > and everything (see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85091#c3). > > MM> COLLECT_GCC_OPTIONS='-c' '-std=c++1z' '-O2' '-Wnonnull' > MM> '-Woverloaded-virtual' '-v' '-o' 'warn.o' '-shared-libgcc' > MM> '-mtune=generic' '-march=pentiumpro' > MM> /usr/bin/i686-w64-mingw32-as -v -o warn.o /tmp/cc9O6U4l.s > MM> GNU assembler version 2.28 (i686-w64-mingw32) using BFD version (GNU > MM> Binutils) 2.28 > MM> COMPILER_PATH=/usr/lib/gcc/i686-w64-mingw32/7.2-win32/:/usr/lib/gcc/i686-w64-mingw32/7.2-win32/:/usr/lib/gcc/i686-w64-mingw32/:/usr/lib/gcc/i686-w64-mingw32/7.2-win32/:/usr/lib/gcc/i686-w64-mingw32/:/usr/lib/gcc/i686-w64-mingw32/7.2-win32/../../../../i686-w64-mingw32/bin/ > MM> LIBRARY_PATH=/usr/lib/gcc/i686-w64-mingw32/7.2-win32/:/usr/lib/gcc/i686-w64-mingw32/7.2-win32/../../../../i686-w64-mingw32/lib/../lib/:/usr/lib/gcc/i686-w64-mingw32/7.2-win32/../../../../i686-w64-mingw32/lib/ > MM> COLLECT_GCC_OPTIONS='-c' '-std=c++1z' '-O2' '-Wnonnull' > MM> '-Woverloaded-virtual' '-v' '-o' 'warn.o' '-shared-libgcc' > MM> '-mtune=generic' '-march=pentiumpro' > MM> > MM> And then: > MM> > MM> $ objdump -d warn.o | grep -A 2 test_main > MM> 000001a0 <__Z9test_mainiPPc>: > MM> 1a0: 31 c0 xor %eax,%eax > MM> 1a2: c3 ret > > But here it gives: > > % objdump -d warn.o | grep -A 2 test_main > 000001a0 <__Z9test_mainiPPc>: > 1a0: f0 83 05 4c 00 00 00 lock addl $0x1,0x4c > 1a7: 01 > > MM> So I suspect the difference is rather in binutils, mine is still: > MM> > MM> GNU assembler version 2.28 (i686-w64-mingw32) using BFD version (GNU > MM> Binutils) 2.28 > > It's true that I'm using 2.29.1 (from Buster), but I'm not sure if this > can explain the problem because I also see the wrong instruction in the > assembly file (16795.s) if I add -save-temps to the compiler command line. > And binutils doesn't affect this, does it? > > The only other thing that might differ that I can think of seems to be > completely unrelated, but, just in case it still matters: is your system > a normal Linux installation or, like mine, a chroot inside one? Because > I've tested this, from the beginning, in a Buster chroot on a Stretch > system (on 2 different physical machines) and in a Sid chroot on a Jessie > system (on yet another machine). I'm using chroot to isolate the tests, but > could it be that gcc somehow misbehaves inside a chroot? Again, I realize > that there is no good reason whatsoever for this to be the case, but after > seeing so many impossible things already, it wouldn't even seem that > surprising to me. > > For the record, I'm creating my chroots using commands like this: > > # debootstrap --arch amd64 sid /srv/chroot/sid-amd64 http://httpredir.debian.org/debian > # mount -t proc proc /srv/chroot/sid-amd64/proc > # mount -t devpts devpts /src/chroot/sid-amd64/dev/pts > # chroot /srv/chroot/sid-amd64 apt install g++-mingw-w64-i686 > > > I guess I'll need to update one of my real Stretch systems to Buster and > try redoing the test outside of chroot -- unless you're using a chroot as > well and so this is not the source of the problem? Well the issue is totally reproducible here. # i686-w64-mingw32-g++ -c -std=c++17 -O2 -Wnonnull -Woverloaded-virtual -v 16795.cpp -o warn.o Using built-in specs. COLLECT_GCC=i686-w64-mingw32-g++ Target: i686-w64-mingw32 Configured with: ../../src/configure --build=x86_64-linux-gnu --prefix=/usr --includedir='/usr/include' --mandir='/usr/share/man' --infodir='/usr/share/info' --sysconfdir=/etc --localstatedir=/var --disable-silent-rules --libdir='/usr/lib/x86_64-linux-gnu' --libexecdir='/usr/lib/x86_64-linux-gnu' --disable-maintainer-mode --disable-dependency-tracking --prefix=/usr --enable-shared --enable-static --disable-multilib --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --libdir=/usr/lib --enable-libstdcxx-time=yes --with-tune=generic --with-headers=/usr/i686-w64-mingw32/include --enable-version-specific-runtime-libs --enable-fully-dynamic-string --enable-libgomp --enable-languages=c,c++,fortran,objc,obj-c++,ada --enable-lto --with-plugin-ld --enable-threads=win32 --program-suffix=-win32 --program-prefix=i686-w64-mingw32- --target=i686-w64-mingw32 --with-as=/usr/bin/i686-w64-mingw32-as --with-ld=/usr/bin/i686-w64-mingw32-ld --enable-libatomic --enable-libstdcxx-filesystem-ts=yes Thread model: win32 gcc version 7.2-win32 20180123 (GCC) COLLECT_GCC_OPTIONS='-c' '-std=c++1z' '-O2' '-Wnonnull' '-Woverloaded-virtual' '-v' '-o' 'warn.o' '-shared-libgcc' '-mtune=generic' '-march=pentiumpro' /usr/lib/gcc/i686-w64-mingw32/7.2-win32/cc1plus -quiet -v -U_REENTRANT 16795.cpp -quiet -dumpbase 16795.cpp -mtune=generic -march=pentiumpro -auxbase-strip warn.o -O2 -Wnonnull -Woverloaded-virtual -std=c++1z -version -o /tmp/ccPhl5Oq.s GNU C++14 (GCC) version 7.2-win32 20180123 (i686-w64-mingw32) compiled by GNU C version 7.2.0, GMP version 6.1.2, MPFR version 4.0.1-rc1, MPC version 1.1.0, isl version isl-0.18-GMP warning: MPFR header version 4.0.1-rc1 differs from library version 4.0.1. GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072 ignoring nonexistent directory "/usr/lib/gcc/i686-w64-mingw32/7.2-win32/../../../../i686-w64-mingw32/sys-include" #include "..." search starts here: #include <...> search starts here: /usr/lib/gcc/i686-w64-mingw32/7.2-win32/include/c++ /usr/lib/gcc/i686-w64-mingw32/7.2-win32/include/c++/i686-w64-mingw32 /usr/lib/gcc/i686-w64-mingw32/7.2-win32/include/c++/backward /usr/lib/gcc/i686-w64-mingw32/7.2-win32/include /usr/lib/gcc/i686-w64-mingw32/7.2-win32/include-fixed /usr/lib/gcc/i686-w64-mingw32/7.2-win32/../../../../i686-w64-mingw32/include End of search list. GNU C++14 (GCC) version 7.2-win32 20180123 (i686-w64-mingw32) compiled by GNU C version 7.2.0, GMP version 6.1.2, MPFR version 4.0.1-rc1, MPC version 1.1.0, isl version isl-0.18-GMP warning: MPFR header version 4.0.1-rc1 differs from library version 4.0.1. GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072 Compiler executable checksum: 4c0706b346120c11493ae8cc1ecc0022 16795.cpp: In function 'unsigned int _get_output_format()': 16795.cpp:316:25: warning: 'unsigned int _get_output_format()' redeclared without dllimport attribute: previous dllimport ignored [-Wattributes] extern "C" unsigned int _get_output_format(void) {return 1;} ^~~~~~~~~~~~~~~~~~ COLLECT_GCC_OPTIONS='-c' '-std=c++1z' '-O2' '-Wnonnull' '-Woverloaded-virtual' '-v' '-o' 'warn.o' '-shared-libgcc' '-mtune=generic' '-march=pentiumpro' /usr/bin/i686-w64-mingw32-as -v -o warn.o /tmp/ccPhl5Oq.s GNU assembler version 2.29.1 (i686-w64-mingw32) using BFD version (GNU Binutils) 2.29.1 COMPILER_PATH=/usr/lib/gcc/i686-w64-mingw32/7.2-win32/:/usr/lib/gcc/i686-w64-mingw32/7.2-win32/:/usr/lib/gcc/i686-w64-mingw32/:/usr/lib/gcc/i686-w64-mingw32/7.2-win32/:/usr/lib/gcc/i686-w64-mingw32/:/usr/lib/gcc/i686-w64-mingw32/7.2-win32/../../../../i686-w64-mingw32/bin/ LIBRARY_PATH=/usr/lib/gcc/i686-w64-mingw32/7.2-win32/:/usr/lib/gcc/i686-w64-mingw32/7.2-win32/../../../../i686-w64-mingw32/lib/../lib/:/usr/lib/gcc/i686-w64-mingw32/7.2-win32/../../../../i686-w64-mingw32/lib/ COLLECT_GCC_OPTIONS='-c' '-std=c++1z' '-O2' '-Wnonnull' '-Woverloaded-virtual' '-v' '-o' 'warn.o' '-shared-libgcc' '-mtune=generic' '-march=pentiumpro' # i686-w64-mingw32-objdump -d warn.o | grep -A 2 test_main 000001a0 <__Z9test_mainiPPc>: 1a0: f0 83 05 4c 00 00 00 lock addl $0x1,0x4c 1a7: 01
