Linking VapourSynth suddenly fails in MSYS2/MinGW64/GCC 14.2

[LigH]

Summary of the bug:

Compiling ffmpeg including VapourSynth, specifically linking the "alternative vapoursynth demuxer", worked last week, fails now.
​M-AB-S issue 2766
​logs.zip collected by M-AB-S

How to reproduce:

CPPFLAGS: 
CFLAGS: -D_FORTIFY_SOURCE=2 -fstack-protector-strong -mtune=generic -O2 -pipe -D__USE_MINGW_ANSI_STDIO=1 -mthreads
CXXFLAGS: -D_FORTIFY_SOURCE=2 -fstack-protector-strong -mtune=generic -O2 -pipe -D__USE_MINGW_ANSI_STDIO=1
LDFLAGS: -D_FORTIFY_SOURCE=2 -fstack-protector-strong -mtune=generic -O2 -pipe -D__USE_MINGW_ANSI_STDIO=1 -static-libgcc -static-libstdc++
make -j4 

{...}
LD	ffmpeg_g.exe
LD	ffplay_g.exe
LD	ffprobe_g.exe
G:/MABS/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: libavformat/libavformat.a(vapoursynth_alt.o):vapoursynth_al:(.text.unlikely+0x2f): undefined reference to `__imp_vsscript_freeScript'
G:/MABS/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: libavformat/libavformat.a(vapoursynth_alt.o):vapoursynth_al:(.text.unlikely+0x35): undefined reference to `__imp_vsscript_finalize'
G:/MABS/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: libavformat/libavformat.a(vapoursynth_alt.o):vapoursynth_al:(.text.unlikely+0x56): undefined reference to `__imp_vsscript_init'
G:/MABS/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: libavformat/libavformat.a(vapoursynth_alt.o):vapoursynth_al:(.text.unlikely+0x7e): undefined reference to `__imp_vsscript_getApiVersion'
G:/MABS/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: libavformat/libavformat.a(vapoursynth_alt.o):vapoursynth_al:(.text.unlikely+0xb4): undefined reference to `__imp_vsscript_getVSApi2'
G:/MABS/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: libavformat/libavformat.a(vapoursynth_alt.o):vapoursynth_al:(.text.unlikely+0xf1): undefined reference to `__imp_vsscript_evaluateFile'
G:/MABS/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: libavformat/libavformat.a(vapoursynth_alt.o):vapoursynth_al:(.text.unlikely+0x121): undefined reference to `__imp_vsscript_getOutput'
G:/MABS/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: libavformat/libavformat.a(vapoursynth_alt.o):vapoursynth_al:(.text.unlikely+0x2f): undefined reference to `__imp_vsscript_freeScript'
G:/MABS/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: libavformat/libavformat.a(vapoursynth_alt.o):vapoursynth_al:(.text.unlikely+0x552): undefined reference to `__imp_vsscript_freeScript'
G:/MABS/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: libavformat/libavformat.a(vapoursynth_alt.o):vapoursynth_al:(.text.unlikely+0x35): undefined reference to `__imp_vsscript_finalize'
G:/MABS/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: libavformat/libavformat.a(vapoursynth_alt.o):vapoursynth_al:(.text.unlikely+0x55f): undefined reference to `__imp_vsscript_finalize'
G:/MABS/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: libavformat/libavformat.a(vapoursynth_alt.o):vapoursynth_al:(.text.unlikely+0x56): undefined reference to `__imp_vsscript_init'
G:/MABS/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: libavformat/libavformat.a(vapoursynth_alt.o):vapoursynth_al:(.text.unlikely+0x7e): undefined reference to `__imp_vsscript_getApiVersion'
G:/MABS/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: libavformat/libavformat.a(vapoursynth_alt.o):vapoursynth_al:(.text.unlikely+0xb4): undefined reference to `__imp_vsscript_getVSApi2'
G:/MABS/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: libavformat/libavformat.a(vapoursynth_alt.o):vapoursynth_al:(.text.unlikely+0xf1): undefined reference to `__imp_vsscript_evaluateFile'
G:/MABS/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: libavformat/libavformat.a(vapoursynth_alt.o):vapoursynth_al:(.text.unlikely+0x121): undefined reference to `__imp_vsscript_getOutput'
G:/MABS/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: libavformat/libavformat.a(vapoursynth_alt.o):vapoursynth_al:(.text.unlikely+0x552): undefined reference to `__imp_vsscript_freeScript'
G:/MABS/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: libavformat/libavformat.a(vapoursynth_alt.o):vapoursynth_al:(.text.unlikely+0x55f): undefined reference to `__imp_vsscript_finalize'
G:/MABS/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: libavformat/libavformat.a(vapoursynth_alt.o):vapoursynth_al:(.text.unlikely+0x2f): undefined reference to `__imp_vsscript_freeScript'
G:/MABS/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: libavformat/libavformat.a(vapoursynth_alt.o):vapoursynth_al:(.text.unlikely+0x35): undefined reference to `__imp_vsscript_finalize'
G:/MABS/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: libavformat/libavformat.a(vapoursynth_alt.o):vapoursynth_al:(.text.unlikely+0x56): undefined reference to `__imp_vsscript_init'
G:/MABS/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: libavformat/libavformat.a(vapoursynth_alt.o):vapoursynth_al:(.text.unlikely+0x7e): undefined reference to `__imp_vsscript_getApiVersion'
G:/MABS/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: libavformat/libavformat.a(vapoursynth_alt.o):vapoursynth_al:(.text.unlikely+0xb4): undefined reference to `__imp_vsscript_getVSApi2'
G:/MABS/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: libavformat/libavformat.a(vapoursynth_alt.o):vapoursynth_al:(.text.unlikely+0xf1): undefined reference to `__imp_vsscript_evaluateFile'
G:/MABS/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: libavformat/libavformat.a(vapoursynth_alt.o):vapoursynth_al:(.text.unlikely+0x121): undefined reference to `__imp_vsscript_getOutput'
G:/MABS/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: libavformat/libavformat.a(vapoursynth_alt.o):vapoursynth_al:(.text.unlikely+0x552): undefined reference to `__imp_vsscript_freeScript'
G:/MABS/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: libavformat/libavformat.a(vapoursynth_alt.o):vapoursynth_al:(.text.unlikely+0x55f): undefined reference to `__imp_vsscript_finalize'
collect2.exe: error: ld returned 1 exit status
collect2.exe: error: ld returned 1 exit status
make: *** [/build/ffmpeg-git/Makefile:141: ffprobe_g.exe] Error 1
make: *** Waiting for unfinished jobs....
make: *** [/build/ffmpeg-git/Makefile:141: ffplay_g.exe] Error 1
collect2.exe: error: ld returned 1 exit status
make: *** [/build/ffmpeg-git/Makefile:141: ffmpeg_g.exe] Error 1
LD	ffmpeg_g.exe
G:/MABS/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: libavformat/libavformat.a(vapoursynth_alt.o):vapoursynth_al:(.text.unlikely+0x2f): undefined reference to `__imp_vsscript_freeScript'
G:/MABS/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: libavformat/libavformat.a(vapoursynth_alt.o):vapoursynth_al:(.text.unlikely+0x35): undefined reference to `__imp_vsscript_finalize'
G:/MABS/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: libavformat/libavformat.a(vapoursynth_alt.o):vapoursynth_al:(.text.unlikely+0x56): undefined reference to `__imp_vsscript_init'
G:/MABS/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: libavformat/libavformat.a(vapoursynth_alt.o):vapoursynth_al:(.text.unlikely+0x7e): undefined reference to `__imp_vsscript_getApiVersion'
G:/MABS/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: libavformat/libavformat.a(vapoursynth_alt.o):vapoursynth_al:(.text.unlikely+0xb4): undefined reference to `__imp_vsscript_getVSApi2'
G:/MABS/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: libavformat/libavformat.a(vapoursynth_alt.o):vapoursynth_al:(.text.unlikely+0xf1): undefined reference to `__imp_vsscript_evaluateFile'
G:/MABS/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: libavformat/libavformat.a(vapoursynth_alt.o):vapoursynth_al:(.text.unlikely+0x121): undefined reference to `__imp_vsscript_getOutput'
G:/MABS/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: libavformat/libavformat.a(vapoursynth_alt.o):vapoursynth_al:(.text.unlikely+0x552): undefined reference to `__imp_vsscript_freeScript'
G:/MABS/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/14.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: libavformat/libavformat.a(vapoursynth_alt.o):vapoursynth_al:(.text.unlikely+0x55f): undefined reference to `__imp_vsscript_finalize'
collect2.exe: error: ld returned 1 exit status
make: *** [/build/ffmpeg-git/Makefile:141: ffmpeg_g.exe] Error 1

[mkver]

This involves a custom demuxer and is therefore not our bug.