Fix omp

[Vollstrecker]

Superseedes #34
Fixed and simplified omp detection for homebrewed libopenmp plus testing that stuff.

[smessmer]

Is the plan to just land this or to also land #34 ? The goal of #34 is to add /opt/homebrew/opt to the path, which this PR doesn't seem to be doing. I would be surprised if this PR worked on Apple Silicon Macs. Were you able to test that?

[Vollstrecker]

Should work now also.

[abdes]

This (7fbbe2e) does not work with:

❯ uname -a
Darwin Abdessattars-MacBook-Pro.local 22.1.0 Darwin Kernel Version 22.1.0: Sun Oct  9 20:15:52 PDT 2022; root:xnu-8792.41.9~2/RELEASE_ARM64_T8112 arm64

I installed libomp, and it went under /opt/homebrew/opt.

==> Pouring libomp--15.0.4.arm64_ventura.bottle.tar.gz
==> Caveats
libomp is keg-only, which means it was not symlinked into /opt/homebrew,
because it can override GCC headers and result in broken builds.

For compilers to find libomp you may need to set:
  export LDFLAGS="-L/opt/homebrew/opt/libomp/lib"
  export CPPFLAGS="-I/opt/homebrew/opt/libomp/include"

This is the output of the configure I run:

❯ cmake .. -D CMAKE_BUILD_TYPE=Debug -G Ninja -D CMAKE_MAKE_PROGRAM=ninja -D USE_CCACHE=ON -D CMAKE_VERBOSE_MAKEFILE=ON -D USE_OPENMP=ON
=> Project : cryptopp v8.7.0 (7fbbe2e27b42)
-- Using ccache (/opt/homebrew/bin/ccache) (via wrapper).
-- CPM: adding package Ccache.cmake@1.2.3 (v1.2.3)
-- Using ccache: /opt/homebrew/bin/ccache
-- downloading/updating cryptopp
-- cryptopp directory found, pulling...
From https://github.com/weidai11/cryptopp
 * branch              master     -> FETCH_HEAD
-- Crypto++ auto fetched at: /Users/abdessattar/Projects/cryptopp-cmake/_build/_deps/cryptopp
-- Adding install integration test: int-install-default
-- Adding install integration test: int-install-prefix
=> Module : cryptopp
-- [cryptopp] CMake version 3.25.0
-- [cryptopp] System Darwin
-- [cryptopp] Processor arm64
-- [cryptopp]     CMAKE_OSX_ARCHITECTURES :
-- [cryptopp] CMAKE_HOST_SYSTEM_PROCESSOR : arm64
-- [cryptopp]      CMAKE_SYSTEM_PROCESSOR : arm64
-- [cryptopp] Target architecture detected as: arm64 -> CRYPTOPP_ARMV8
-- Could NOT find OpenMP_C (missing: OpenMP_C_FLAGS OpenMP_C_LIB_NAMES)
-- Could NOT find OpenMP_CXX (missing: OpenMP_CXX_FLAGS OpenMP_CXX_LIB_NAMES)
-- Could NOT find OpenMP (missing: OpenMP_C_FOUND OpenMP_CXX_FOUND)
-- OpenMP: Applying workaround for OSX OpenMP with old cmake that doesn't have FindOpenMP
-- OpenMP: Applying workaround for old CMake that doesn't define FindOpenMP using targets
-- [cryptopp] Generating cmake package config files
-- [cryptopp] Generating pkgconfig files
-- [cryptopp] Platform: ARMv8
-- [cryptopp] Compiler definitions:  CRYPTOPP_DATA_DIR="/Users/abdessattar/Projects/cryptopp-cmake/_build/_deps/cryptopp";CRYPTOPP_ARM_NEON_HEADER=1;CRYPTOPP_ARM_ACLE_HEADER=1;CRYPTOPP_DISABLE_ARM_CRC32=1;CRYPTOPP_DISABLE_ARM_PMULL=1
-- [cryptopp] Compiler options:
-- [cryptopp] Build type: Debug
-- Configuring done
CMake Error: install(EXPORT "cryptopp_Targets" ...) includes target "cryptopp" which requires target "OpenMP_TARGET" that is not in any export set.
-- Generating done
CMake Generate step failed.  Build files cannot be regenerated correctly.

[abdes]

Should work now also.

This (f00503d) works.

Please change the commit messages to meet the expectations of commitlint. Start with 'fix: ', have a short one line message, an empty line, then details of the commit changes. I use this to automatically generate the changelog 😄

Run npx commitlint --from 3d8a0a576bccb718cebd4ed97a09feb520e60641 --to f00503db7a5a3f25f274baf364f82f1896d9577a --verbose
[4](https://github.com/abdes/cryptopp-cmake/actions/runs/3499225665/jobs/5860544849#step:5:5)
⧗   input: Fix: Detection of libomp on Silicon Macs
[5](https://github.com/abdes/cryptopp-cmake/actions/runs/3499225665/jobs/5860544849#step:5:6)
✖   subject must not be sentence-case, start-case, pascal-case, upper-case [subject-case]
[6](https://github.com/abdes/cryptopp-cmake/actions/runs/3499225665/jobs/5860544849#step:5:7)
✖   type must be lower-case [type-case]
[7](https://github.com/abdes/cryptopp-cmake/actions/runs/3499225665/jobs/5860544849#step:5:8)
✖   type must be one of [build, chore, ci, docs, feat, fix, perf, refactor, revert, style, test] [type-enum]
[8](https://github.com/abdes/cryptopp-cmake/actions/runs/3499225665/jobs/5860544849#step:5:9)

[9](https://github.com/abdes/cryptopp-cmake/actions/runs/3499225665/jobs/5860544849#step:5:10)
✖   found 3 problems, 0 warnings
[10](https://github.com/abdes/cryptopp-cmake/actions/runs/3499225665/jobs/5860544849#step:5:11)
ⓘ   Get help: https://github.com/conventional-changelog/commitlint/#what-is-commitlint
[11](https://github.com/abdes/cryptopp-cmake/actions/runs/3499225665/jobs/5860544849#step:5:12)

[12](https://github.com/abdes/cryptopp-cmake/actions/runs/3499225665/jobs/5860544849#step:5:13)
⧗   input: Added openmp homebrew test
[13](https://github.com/abdes/cryptopp-cmake/actions/runs/3499225665/jobs/5860544849#step:5:14)
✖   subject may not be empty [subject-empty]
[14](https://github.com/abdes/cryptopp-cmake/actions/runs/3499225665/jobs/5860544849#step:5:15)
✖   type may not be empty [type-empty]
[15](https://github.com/abdes/cryptopp-cmake/actions/runs/3499225665/jobs/5860544849#step:5:16)

[16](https://github.com/abdes/cryptopp-cmake/actions/runs/3499225665/jobs/5860544849#step:5:17)
✖   found 2 problems, 0 warnings
[17](https://github.com/abdes/cryptopp-cmake/actions/runs/3499225665/jobs/5860544849#step:5:18)
ⓘ   Get help: https://github.com/conventional-changelog/commitlint/#what-is-commitlint
[18](https://github.com/abdes/cryptopp-cmake/actions/runs/3499225665/jobs/5860544849#step:5:19)

[19](https://github.com/abdes/cryptopp-cmake/actions/runs/3499225665/jobs/5860544849#step:5:20)
⧗   input: Fix detection of homebrewed libomp
[20](https://github.com/abdes/cryptopp-cmake/actions/runs/3499225665/jobs/5860544849#step:5:21)
✖   subject may not be empty [subject-empty]
[21](https://github.com/abdes/cryptopp-cmake/actions/runs/3499225665/jobs/5860544849#step:5:22)
✖   type may not be empty [type-empty]
[22](https://github.com/abdes/cryptopp-cmake/actions/runs/3499225665/jobs/5860544849#step:5:23)

[23](https://github.com/abdes/cryptopp-cmake/actions/runs/3499225665/jobs/5860544849#step:5:24)
✖   found 2 problems, 0 warnings
[24](https://github.com/abdes/cryptopp-cmake/actions/runs/3499225665/jobs/5860544849#step:5:25)
ⓘ   Get help: https://github.com/conventional-changelog/commitlint/#what-is-commitlint

[abdes]

@Vollstrecker This is good to go for a squash and merge with a conventional commit compliant message please 😄. I will leave it to you to do the merge... Thanks for your excellent contribution as usual. Thanks @smessmer for your help.

[Vollstrecker]

Done, I guess the description should be ok also, but this check doesn't seem to run on merge.

[abdes]

It's ok.
I recommend you do the simple steps in https://github.com/abdes/cryptopp-cmake/blob/master/CONTRIBUTING.md#conventional-commits to make your life much easier for future contributions. Your commit messages will be locally listed immediately before you push them.