i686 libstdc++-6.dll built after latest mingw crt/winpthreads/etc update breaks things

[jeremyd2019]

After installing a freshly built gcc, things are silently failing. cmake was the first thing I saw, but then when I tried to find out what was happening I saw gdb was also silently failing.
the most likely thing that changed between when it worked and now would be the mingw crt/etc packages were updated

dependency walker is showing libstdc++ has undefined imports __emutls_v._ZSt11_once_call and __emutls_v.Zst15_once_callable. Those symbols are present in the existing/working libstdc++-6.dll.

libstdc++-6.dll from CI rebuild of gcc has the issue. Local build of gcc after downgrading mingw packages(pacman -U /var/cache/pacman/pkg/mingw-w64-i686-*-8.0.0.5*) ongoing, but there is already a stage3 libstdc++-6.dll, which defines those symbols.

[jeremyd2019]

Exact packages downgraded:

/var/cache/pacman/pkg/mingw-w64-i686-crt-git-8.0.0.5966.f5da805f-1-any.pkg.tar.zst
/var/cache/pacman/pkg/mingw-w64-i686-headers-git-8.0.0.5966.f5da805f-1-any.pkg.tar.zst
/var/cache/pacman/pkg/mingw-w64-i686-libmangle-git-8.0.0.5573.a4de8df4-1-any.pkg.tar.xz
/var/cache/pacman/pkg/mingw-w64-i686-libwinpthread-git-8.0.0.5906.c9a21571-1-any.pkg.tar.zst
/var/cache/pacman/pkg/mingw-w64-i686-tools-git-8.0.0.5903.3310d459-1-any.pkg.tar.zst
/var/cache/pacman/pkg/mingw-w64-i686-winpthreads-git-8.0.0.5906.c9a21571-1-any.pkg.tar.zst
/var/cache/pacman/pkg/mingw-w64-i686-winstorecompat-git-8.0.0.5903.3310d459-1-any.pkg.tar.zst

[mati865]

You'd have to inspect build logs but my guess is the linking order is not correct for new build of winpthreads.
After #6955 it gained dependencies on some of mingw-w64 libraries: rust-lang/rust#77208

It should be trivial to confirm it by using ntldd on broken libstdc++-6.dll, if it doesn't print libwinpthread-1.dll then libstdc++ was built without threading support.

[jeremyd2019]

$ ntldd libstdc++-6.dll
        libgcc_s_dw2-1.dll (0x00160000)
        KERNEL32.dll => C:\WINDOWS\SYSTEM32\KERNEL32.dll (0x00ea0000)
        msvcrt.dll => C:\WINDOWS\SYSTEM32\msvcrt.dll (0x00ea0000)
        libwinpthread-1.dll => D:\msys32\mingw32\bin\libwinpthread-1.dll (0x00180000)

[Biswa96]

D:\msys32?

[jeremyd2019]

D:\msys32?

my tablet - stuck with 32-bit windows. I'd fire up a 64-bit VM if necessary, but for this quick check the tablet was fine

I did the build on github though - the logs and artifacts should be available https://github.com/jeremyd2019/MINGW-packages/actions/runs/274408323

[jeremyd2019]

$ nm /mingw32/bin/libstdc++-6.dll | grep -E 'thread|tls' | cut -d' ' -f 3 > old
$ nm libstdc++-6.dll | grep -E 'thread|tls' | cut -d' ' -f 3 > new
$ diff old new
2d1
< __imp____emutls_get_address

[jeremyd2019]

I just came across #6539 (comment). I guess I've got to try the build again locally with newer mingw packages (probably winpthread) and look for a config.log.

[mati865]

@jeremyd2019 it's not going to help. Winpthreads package in the repo already contains that fix.

@lhmouse any idea why that fix does not work after applying #6955 (it adds CPPFLAGS="-D__USE_MINGW_ANSI_STDIO=1" among the other changes).

[jeremyd2019]

I'm not saying that change is going to fix it. I'm saying I want to do another build to confirm exactly why the TLS test fails, if it is the same undefined symbol or some new one

[jeremyd2019]

Same symbol:

configure:28821: /home/adminuser/MINGW-packages/mingw-w64-gcc/src/build-i686-w64-mingw32/./gcc/xgcc -B/home/adminuser/MINGW-packages/mingw-w64-gcc/src/build-i686-w64-mingw32/./gcc/ -L/mingw32/i686-w64-mingw32/lib -L/mingw32/lib -isystem /mingw32/i686-w64-mingw32/include -isystem /mingw32/include -B/mingw32/i686-w64-mingw32/bin/ -B/mingw32/i686-w64-mingw32/lib/ -isystem /mingw32/i686-w64-mingw32/include -isystem /mingw32/i686-w64-mingw32/sys-include   -fno-checking -o conftest.exe -g -march=i686 -mtune=generic -O2 -pipe  -static -pipe -Wl,--dynamicbase,--nxcompat,--no-seh -Wl,--large-address-aware conftest.c  >&5
C:\msys64\mingw32\i686-w64-mingw32\bin\ld.exe: C:/msys64/mingw32/i686-w64-mingw32/lib\libmingwex.a(lib32_libmingwex_a-mingw_pformat.o): in function `_pformat_int':
C:/_/M/mingw-w64-crt-git/src/mingw-w64/mingw-w64-crt/stdio/mingw_pformat.c:797: undefined reference to `__umoddi3'
collect2.exe: error: ld returned 1 exit status
configure:28821: $? = 1

[lhmouse]

@mati865 winpthreads should be built with -D__USE_MINGW_ANSI_STDIO=0 (zero instead of one). Please try reverting the commit in #6953 and rebuilding.

[jeremyd2019]

Or maybe just filter the -D__USE_MINGW_ANSI_STDIO=1 out of the CPPFLAGS in that PKGBUILD so it continues to get the benefit of the LDFLAGS