Programs that previously did not require libc++.dll and libunwind.dll began requiring them after llvm-mingw version 18.1.8

[Aniark]

Compiling FFmpeg with an llvm-mingw version greater than 18.1.8 and executing ffmpeg.exe will prompt for two DLLs: libc++.dll and libunwind.dll; version less than or equal to 18.1.8 will not produce this prompt.

CRT type: both MSVCRT and UCRT
Compiled FFmpeg version: git d01608e
Configure parameters:

./configure \
--enable-static --disable-ffplay --disable-ffprobe --disable-doc --disable-debug \
--pkg-config=pkg-config \
--arch=amd64 --target-os=mingw64 \
--prefix=$PWD \
--cross-prefix=x86_64-w64-mingw32-

I know adding the --extra-ldflags=-static parameter resolves the error, but I want to understand why the program, which previously didn't require these DLLs, now needs them.

[mstorsjo]

This is due to a new component in ffmpeg, vsrc_gfxcapture, https://code.ffmpeg.org/FFmpeg/FFmpeg/commit/36e374efb05a2ad81369980de98a0d78381ec81f, which is implemented in C++. If you have an older toolchain, it probably lacks the necessary headers for building this, so you don't end up with the C++ dependency, but if you have a new new enough toolchain, this is enabled by default.