fix loading of CURL and Backtracing library with CMake (#215)

to build on FreeBSD with default compiler (Clang 4.0)

.circleci/config.yml

@@ -49,7 +49,7 @@ references:
         sudo chmod o-w /etc/apt/sources.list.d/clang.list
 
         DEBIAN_FRONTEND=noninteractive sudo apt-get update -qq
-        DEBIAN_FRONTEND=noninteractive sudo apt-get install -y git ccache $APT_COMPILER_PACKAGE cmake make libcurl4-openssl-dev libcrypto++-dev libssl-dev libfuse-dev python
+        DEBIAN_FRONTEND=noninteractive sudo apt-get install -y git ccache $APT_COMPILER_PACKAGE cmake3 make libcurl4-openssl-dev libcrypto++-dev libssl-dev libfuse-dev python
         # Use /dev/urandom when /dev/random is accessed to use less entropy
         sudo cp -a /dev/urandom /dev/random
 

CMakeLists.txt

@@ -1,4 +1,5 @@
-cmake_minimum_required(VERSION 2.8 FATAL_ERROR)
+cmake_minimum_required(VERSION 3.0 FATAL_ERROR)
+cmake_policy(VERSION 2.8)
 
 # note: for clang-tidy, we need cmake 3.6, or (if the return code should be handled correctly, e.g. on CI), we need 3.8.
 

README.md

@@ -24,7 +24,7 @@ Requirements
 ------------
   - Git (for getting the source code)
   - GCC version >= 4.8 or Clang >= 3.7
-  - CMake version >= 2.8
+  - CMake version >= 3.0 
   - libcurl4 (including development headers)
   - Boost libraries version >= 1.56 (including development headers)
     - filesystem

src/cpp-utils/CMakeLists.txt

@@ -50,7 +50,21 @@ set(SOURCES
 
 add_library(${PROJECT_NAME} STATIC ${SOURCES})
 
-target_link_libraries(${PROJECT_NAME} PUBLIC pthread curl)
+find_package(CURL)
+if(NOT ${CURL_FOUND})
+	message(FATAL_ERROR "CURL library not found")                                                 
+endif()
+include_directories(${CURL_INCLUDE_DIRS})
+target_link_libraries(${PROJECT_NAME} PUBLIC ${CURL_LIBRARIES})                                       
+
+find_package(Backtrace)
+if(NOT ${Backtrace_FOUND})
+	message(FATAL_ERROR "Backtrace library not found")                                            
+endif()
+include_directories(${Backtrace_INCLUDE_DIRS})
+target_link_libraries(${PROJECT_NAME} PUBLIC ${Backtrace_LIBRARIES}) 
+
+target_link_libraries(${PROJECT_NAME} PUBLIC pthread)
 
 # TODO From Crypto++ 5.7 on, it should support cmake with find_package() instead of find_library().
 find_library_with_path(CryptoPP cryptopp CRYPTOPP_LIB_PATH)