Still trying to make it work… but now I get a build error …
[ 15%] Building C object src/CMakeFiles/lib_darktable.dir/common/collection.c.obj
In file included from C:/msys64/home/Philippe/dt-org/src/common/collection.c:20:
C:/msys64/home/Philippe/dt-org/src/common/collection.c: In function 'dt_collection_shift_image_positions':
C:/msys64/home/Philippe/dt-org/src/common/collection.c:1392:84: error: left shift count >= width of type [-Werror=shift-count-overflow]
DT_DEBUG_SQLITE3_BIND_INT64(stmt, 3, (image_position & 0xFFFFFFFF00000000) + (1l << 32));
^~
C:/msys64/home/Philippe/dt-org/src/common/debug.h:65:97: note: in definition of macro '__DT_DEBUG_ASSERT__'
_Pragma("GCC diagnostic push") _Pragma("GCC diagnostic ignored \"-Wshadow\"") const int x = xin; \
^~~
C:/msys64/home/Philippe/dt-org/src/common/collection.c:1392:3: note: in expansion of macro 'DT_DEBUG_SQLITE3_BIND_INT64'
DT_DEBUG_SQLITE3_BIND_INT64(stmt, 3, (image_position & 0xFFFFFFFF00000000) + (1l << 32));
^~~~~~~~~~~~~~~~~~~~~~~~~~~
cc1.exe: all warnings being treated as errors
make[2]: *** [src/CMakeFiles/lib_darktable.dir/build.make:168: src/CMakeFiles/lib_darktable.dir/common/collection.c.obj] Error 1
make[1]: *** [CMakeFiles/Makefile2:1439: src/CMakeFiles/lib_darktable.dir/all] Error 2
make: *** [Makefile:152: all] Error 2
EDIT
- back to commit 0588beb880363f9e0092010ee4f5416217d8f8ef (15th september) this error goes out.
- Using

(from https://sourceforge.net/projects/msys2/files/REPOS/MINGW/x86_64/) instead of the file coming with MSY2 seems to solve the dt crash above.
EDIT2