deps: Move and fix jsoncpp.cmake from deps submodule

This copies jsoncpp.cmake from ethereum/cpp-dependencies repo and adds BUILD_BYPRODUCT information to ExternalProject configuration (required by Ninja).

CMakeLists.txt

@@ -15,7 +15,7 @@ option(SOLC_LINK_STATIC "Link solc executable statically on supported platforms"
 
 # Let's find our dependencies
 include(EthDependencies)
-include(deps/jsoncpp.cmake)
+include(jsoncpp)
 
 find_package(Threads)
 

cmake/jsoncpp.cmake

@@ -0,0 +1,50 @@
+include(ExternalProject)
+
+if (${CMAKE_SYSTEM_NAME} STREQUAL "Emscripten")
+    set(JSONCPP_CMAKE_COMMAND emcmake cmake)
+else()
+    set(JSONCPP_CMAKE_COMMAND ${CMAKE_COMMAND})
+endif()
+
+# Disable implicit fallthrough warning in jsoncpp for gcc >= 7 until the upstream handles it properly
+if (("${CMAKE_CXX_COMPILER_ID}" MATCHES "GNU") AND CMAKE_CXX_COMPILER_VERSION VERSION_GREATER 7.0)
+    set(JSONCCP_EXTRA_FLAGS -Wno-implicit-fallthrough)
+else()
+    set(JSONCCP_EXTRA_FLAGS "")
+endif()
+
+set(prefix "${CMAKE_BINARY_DIR}/deps")
+set(JSONCPP_LIBRARY "${prefix}/lib/${CMAKE_STATIC_LIBRARY_PREFIX}jsoncpp${CMAKE_STATIC_LIBRARY_SUFFIX}")
+set(JSONCPP_INCLUDE_DIR "${prefix}/include")
+
+set(byproducts "")
+if(CMAKE_VERSION VERSION_GREATER 3.1)
+    set(byproducts BUILD_BYPRODUCTS "${JSONCPP_LIBRARY}")
+endif()
+
+ExternalProject_Add(jsoncpp-project
+    PREFIX "${prefix}"
+    DOWNLOAD_NAME jsoncpp-1.7.7.tar.gz
+    URL https://github.com/open-source-parsers/jsoncpp/archive/1.7.7.tar.gz
+    URL_HASH SHA256=087640ebcf7fbcfe8e2717a0b9528fff89c52fcf69fa2a18cc2b538008098f97
+    CMAKE_COMMAND ${JSONCPP_CMAKE_COMMAND}
+    CMAKE_ARGS -DCMAKE_INSTALL_PREFIX=<INSTALL_DIR>
+               -DCMAKE_C_COMPILER=${CMAKE_C_COMPILER}
+               -DCMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER}
+               # Build static lib but suitable to be included in a shared lib.
+               -DCMAKE_POSITION_INDEPENDENT_CODE=${BUILD_SHARED_LIBS}
+               -DJSONCPP_WITH_TESTS=OFF
+               -DJSONCPP_WITH_PKGCONFIG_SUPPORT=OFF
+               -DCMAKE_CXX_FLAGS=${JSONCCP_EXTRA_FLAGS}
+    # Overwrite build and install commands to force Release build on MSVC.
+    BUILD_COMMAND cmake --build <BINARY_DIR> --config Release
+    INSTALL_COMMAND cmake --build <BINARY_DIR> --config Release --target install
+    ${byproducts}
+)
+
+# Create jsoncpp imported library
+add_library(jsoncpp STATIC IMPORTED)
+file(MAKE_DIRECTORY ${JSONCPP_INCLUDE_DIR})  # Must exist.
+set_property(TARGET jsoncpp PROPERTY IMPORTED_LOCATION ${JSONCPP_LIBRARY})
+set_property(TARGET jsoncpp PROPERTY INTERFACE_INCLUDE_DIRECTORIES ${JSONCPP_INCLUDE_DIR})
+add_dependencies(jsoncpp jsoncpp-project)