No need for a FindHWY.cmake

[malaterre]

HWY is build by cmake there should not be a need to write a FindHWY.cmake which are needed only for other build tools (non-cmake type).

[jan-wassenberg]

Can you expand on how FindHWY would be used by non-CMake build tools?

My understanding is that FindHWY would still be useful for CMake builds that wish to use a prebuilt/system Highway for whatever reason. @kfjahnke any thoughts?

[malaterre]

cmake is able to generate those *Config.cmake files that are needed by cmake users. find_package is able to search for HWYConfig.cmake when installed in the correct location.

[jan-wassenberg]

hm, FindHWY also invokes find_package. It's not clear to me that find_package by itself is sufficient, other projects have actually found it useful to add their own FindHWY. It seems to me they wouldn't do that if plain CMake were sufficient?

[malaterre]

It is equivalent...except that generating a HWYConfig.cmake is integrated in cmake directly, no need to manually tweak the FindHWY.cmake anymore (since derived info). Typical steps:

% cat CMakeLists.txt
project(p)
find_package(HWY REQUIRED)

Trigger:

CMake Error at CMakeLists.txt:2 (find_package):
  By not providing "FindHWY.cmake" in CMAKE_MODULE_PATH this project has
  asked CMake to find a package configuration file provided by "HWY", but
  CMake did not find one.

  Could not find a package configuration file provided by "HWY" with any of
  the following names:

    HWYConfig.cmake
    hwy-config.cmake

  Add the installation prefix of "HWY" to CMAKE_PREFIX_PATH or set "HWY_DIR"
  to a directory containing one of the above files.  If "HWY" provides a
  separate development package or SDK, be sure it has been installed.

Since current hwy Debian package does not provide neither FindHWY.cmake nor HWYConfig.cmake...

[malaterre]

For reference:

• https://cmake.org/cmake/help/latest/module/CMakePackageConfigHelpers.html

Not tested but writing HWYConfig.cmake is just a matter of a single cmake line:

write_basic_package_version_file(${CMAKE_CURRENT_BINARY_DIR}/HWYConfigVersion.cmake COMPATIBILITY SameMajorVersion)

[malaterre]

hm, FindHWY also invokes find_package. It's not clear to me that find_package by itself is sufficient, other projects have actually found it useful to add their own FindHWY. It seems to me they wouldn't do that if plain CMake were sufficient?

chicken and egg situation...until hwy install a HWYConfig.cmake the cmake-outside world needs to retrieve info through a findhwy.cmake (just as any non-cmake based build tool).

[malaterre]

Not tested but writing HWYConfig.cmake is just a matter of a single cmake line:

Nevermind this was a bit more work than just a single line.

[kfjahnke]

Hi!
I'd like to refer you to my last post to #1084
The issue was closed, but I thought my answer would still be seen. I enclosed a patch against your CMakeLists.txt which should make the find file unnecessary.

[jan-wassenberg]

@malaterre I think I understand the chicken and egg situation. Thanks for explaining and sending the pull request!

@kfjahnke oops, I had indeed missed your post, sorry about that!
Looks like your patch also does something very similar to the pull request here. Let's go with that :)