Cmake on Cygwin: CMake Error: Could not find CMAKE_ROOT

I installed Cmake 3.28.3 using Cygwin installer.

However, cmake produces CMake Error: Could not find CMAKE_ROOT !!!:

$ /bin/cmake --version
CMake Error: Could not find CMAKE_ROOT !!!
CMake has most likely not been installed correctly.
Modules directory not found in
/share/cmake-3.28.3
cmake version 3.28.3

CMake suite maintained and supported by Kitware (kitware.com/cmake).

I installed Cmake 3.25.3 using Cygwin installer.

However, cmake produces CMake Error: Could not find CMAKE_ROOT !!!:

$ /bin/cmake --version
CMake Error: Could not find CMAKE_ROOT !!!
CMake has most likely not been installed correctly.
Modules directory not found in
/share/cmake-3.25.3
cmake version 3.25.3

CMake suite maintained and supported by Kitware (kitware.com/cmake).

System information:

$ uname -a
CYGWIN_NT-10.0-19045 xxx 3.5.3-1.x86_64 2024-04-03 17:25 UTC x86_64 Cygwin

I've already tried to relaunch Cygwin and to reboot the OS. No effect.

Any ideas why this happen and how to fix?

Solution

Your Workaround is the wrong one.

$ /bin/cmake
CMake Error: Could not find CMAKE_ROOT !!!
CMake has most likely not been installed correctly.
....

instead

$ /usr/bin/cmake
Usage

  cmake [options] <path-to-source>
  cmake [options] <path-to-existing-build>
  cmake [options] -S <path-to-source> -B <path-to-build>
  ...

This is is due to the historical peculiarity that on Cygwin /bin and /usr/bin are the same directory

$ mount
D:/cygwin64/bin on /usr/bin type ntfs (binary,auto)
D:/cygwin64/lib on /usr/lib type ntfs (binary,auto)
...

But the package was built as almost all package with /usr/bin in mind and all relative directories start for that one

$ cygcheck -l cmake | grep bin
/usr/bin/ccmake.exe
/usr/bin/cmake.exe
/usr/bin/cpack.exe
/usr/bin/ctest.exe
...

GCC compiler has the same settings.
This is the reason why the PATH should contain only /usr/bin and NOT /bin. See /etc/profile for standard setting.