The dependency versions are not explicitly specified in my installation script 

"pacman -S --needed --noconfirm git zip base-devel mingw-w64-x86_64-autotools mingw-w64-x86_64-toolchain mingw-w64-x86_64-xpm-nox mingw-w64-x86_64-libtiff mingw-w64-x86_64-giflib mingw-w64-x86_64-libpng mingw-w64-x86_64-libjpeg-turbo mingw-w64-x86_64-librsvg mingw-w64-x86_64-libwebp mingw-w64-x86_64-lcms2 mingw-w64-x86_64-gnutls mingw-w64-x86_64-jansson mingw-w64-x86_64-libgccjit mingw-w64-x86_64-libxml2 mingw-w64-x86_64-gnutls mingw-w64-x86_64-zlib mingw-w64-x86_64-harfbuzz mingw-w64-x86_64-tree-sitter mingw-w64-x86_64-sqlite3"


There is a update of the package to gcc 13.2.0 that may be related: https://github.com/msys2/MINGW-packages/commits/master/mingw-w64-gcc

On Mon, Sep 4, 2023, 5:29 AM Eli Zaretskii <eliz@gnu.org> wrote:
> From: voi dfoo <void.foo@gmail.com>
> Date: Sun, 3 Sep 2023 22:06:41 -0700
>
> Occasionally I use appveyor/GitHub Actions to build Emacs for Windows
> using MSYS environment. At some point the build started to fail when
> making .elc files.
>
> I suspect that newer version of dependencies (libgccjit?) caused the
> crash because a previous passing commit now also failed.
>
> I don't have a local environment to investigate further. I don't know
> whether the following information is actionable but here they are

Did you per chance upgrade GCC and/or libgccjit and/or Binutils
between the last successful build and the first failed one?