Windows: tell cmake it's not crosscompiling in MSYS2

[iDunk5400]

This fixes a cmake error in MSYS2 introduced by #4294

[moneromooo-monero]

While I know sfa about cmake/windows, this seems unconditional. Will this actually break cross compiling ?

[iDunk5400]

That's why I used the CMAKE_HOST_WIN32 check, so if host is not Windows it should still work.

[moneromooo-monero]

OK, but that doesn't mean the host is different from the target, does it ?

[iDunk5400]

How would you interpret this ?

CMake Warning at translations/CMakeLists.txt:35 (message):
  CrossCompiling


CMake Error at translations/CMakeLists.txt:37 (INCLUDE):
  INCLUDE could not find load file:

    C:/msys64/home/idunk/monero/build/release/translations/ImportExecutables.cmake

That's without the patch.

https://cmake.org/cmake/help/v3.0/variable/CMAKE_CROSSCOMPILING.html

[moneromooo-monero]

I interpret this as "I'm going to cross compile". My point, however, is that I read the change as "if the host is win32, assume we're not cross compiling", without checking the target, which seems wrong unless there's a subtlety I'm missing.

[iDunk5400]

Those cmake toolchain files are only used in release-static-win32 and release-static-win64 targets. Maybe I'm missing something ?

EDIT: And their debug equivalents.

[moneromooo-monero]

Ah, that does explain then, the target is already fixed :)

Thanks

[iDunk5400]

Hmm, another way of fixing this would be to remove this line. Then CMAKE_SYSTEM and CMAKE_HOST_SYSTEM would match, and CMAKE_CROSSCOMPILING would not be set.

Relevant cmake vars with L29:

-- CMAKE_HOST_SYSTEM=Windows-10.0.17134
-- CMAKE_HOST_SYSTEM_NAME=Windows
-- CMAKE_HOST_SYSTEM_PROCESSOR=AMD64
-- CMAKE_HOST_SYSTEM_VERSION=10.0.17134

-- CMAKE_SYSTEM=Windows
-- CMAKE_SYSTEM_NAME=Windows
-- CMAKE_SYSTEM_PROCESSOR=
-- CMAKE_SYSTEM_VERSION=
-- CMAKE_CROSSCOMPILING=TRUE

Relevant cmake vars without L29:

-- CMAKE_HOST_SYSTEM=Windows-10.0.17134
-- CMAKE_HOST_SYSTEM_NAME=Windows
-- CMAKE_HOST_SYSTEM_PROCESSOR=AMD64
-- CMAKE_HOST_SYSTEM_VERSION=10.0.17134

-- CMAKE_SYSTEM=Windows-10.0.17134
-- CMAKE_SYSTEM_NAME=Windows
-- CMAKE_SYSTEM_PROCESSOR=AMD64
-- CMAKE_SYSTEM_VERSION=10.0.17134
-- CMAKE_CROSSCOMPILING=FALSE

[MoroccanMalinois]

grep -R CMAKE_CROSSCOMPILING Source in cmake source code shows that it's only used to automatically skip execution of binaries, with this exception, in a function named "SetPermissions" :

#ifdef WIN32
  if (Makefile->IsOn("CMAKE_CROSSCOMPILING")) {
    // Store the mode in an NTFS alternate stream.
    std::string mode_t_adt_filename =
      std::string(toFile) + ":cmake_mode_t";

    // Writing to an NTFS alternate stream changes the modification
    // time, so we need to save and restore its original value.
    [...]

I understood it as a way to preserve file permissions when they will be moved to windows, but this could be completely wrong!

So, imho, CMAKE_SYSTEM_NAME Windows should only be set when using mingw on linux, target that doesn't exists in current Makefile (wondering if it just needs a different MSYS2_FOLDER ...)

tl;dr i vote for @iDunk5400 second solution

[iDunk5400]

I agree that not setting CMAKE_SYSTEM_NAME would be the right solution. Closing this in favor of #4342.