@berak Could you please check build process in MinGW environment?

sure, will do.

what i tried:

git checkout master
git pull upstream master  (calib3d changes and such)
git checkout -b 20_12_07 (new branch to test)
git pull https://github.com/alalek/opencv core_update_allocator_stats_type   (since it isn't merged yet)

delete build/CmakeCache.txt (since i had OPENCV_ENABLE_ALLOCATOR_STATS=OFF  there) (needs to delete more ?)
check core/CmakeLists.txt (yes i have the changes from this pr)
run cmake-gui (basically change *nothing*)
  * found "Consider adding OPENCV_ALLOCATOR_STATS_COUNTER_TYPE=int/int64_t according to your build configuration" in the log  (but it's quite hidden in all the "small print" ;(
  * OPENCV_ENABLE_ALLOCATOR_STATS is still ON
  * OPENCV_ALLOCATOR_STATS_COUNTER_TYPE is not set to anything

mingw32-make -j3 install

and WIN, it built the core module allright ! (without settin a type manually even)

but, in retrospect, this all looks a bit messy to me.

if OPENCV_ALLOCATOR_STATS_COUNTER_TYPE is the final (??) variable evaluated from cmake, do we really need OPENCV_ENABLE_ALLOCATOR_STATS or OPENCV_DISABLE_ALLOCATOR_STATS even ?

maybe it could be as simple as: "if there's no type set, don't use the stats"

@berak Thank you!

Initially OPENCV_ALLOCATOR_STATS_COUNTER_TYPE value is defined in C++ code.
Unfortunately it is not enough (macro become over-complicated and extra libraries for linker may be required), so detection is moved to CMake. CMake variable just helps to configure this externally (or force own value).

👍