Fix OpenMP for osx

README.md

@@ -35,6 +35,7 @@ Requirements
   - SSL development libraries (including development headers, e.g. libssl-dev)
   - libFUSE version >= 2.8.6 (including development headers), on Mac OS X instead install osxfuse from https://osxfuse.github.io/
   - Python >= 2.7
+  - OpenMP
 
 You can use the following commands to install these requirements
 
@@ -45,7 +46,7 @@ You can use the following commands to install these requirements
         sudo dnf install git gcc-c++ cmake make libcurl-devel boost-devel boost-static openssl-devel fuse-devel python
 
         # Macintosh
-        brew install cmake boost openssl
+        brew install cmake boost openssl libomp
 
 Build & Install
 ---------------

vendor/cryptopp/CMakeLists.txt

@@ -5,6 +5,13 @@ add_library(cryptopp dummy.cpp)
 target_include_directories(cryptopp SYSTEM INTERFACE ${CMAKE_CURRENT_SOURCE_DIR})
 
 if(NOT DISABLE_OPENMP)
+    if(APPLE AND (CMAKE_CXX_COMPILER_ID STREQUAL "AppleClang" OR CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
+            AND CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL "7.0"
+            AND ßCMAKE_VERSION VERSION_LESS "3.8.0")
+        # Workaround because older cmake on apple doesn't support FindOpenMP
+        set(CMAKE_CXX_FLAGS ${CMAKE_CXX_FLAGS} "-Xclang -fopenmp")
+        target_link_libraries(cryptopp PRIVATE -lomp)
+    else()
         find_package(OpenMP)
         if(OPENMP_FOUND)
             set(CMAKE_CXX_FLAGS ${CMAKE_CXX_FLAGS} ${OpenMP_CXX_FLAGS})
@@ -12,6 +19,7 @@ if(NOT DISABLE_OPENMP)
         else(OPENMP_FOUND)
             message(FATAL_ERROR "Did not find OpenMP. Build with -DDISABLE_OPENMP=ON if you want to allow this and are willing to take the performance hit.")
         endif(OPENMP_FOUND)
+    endif()
 endif(NOT DISABLE_OPENMP)