When using solidity as a third-party library (include it into our
project using FetchContent), we encountered a strange compilation error.
For some reason, cmake considers the root directory of the project as
the root directory of the dependency (solidity). This is because
solidity is incorrectly using CMAKE_SOURCE_DIR variable, which should be
PROJECT_SOURCE_DIR (The former one refers to the top-level source
directory that contains a CMakeLists.txt, while the latter refers to the
source directory of the most recent project() command)
I've created a repo for demonstration (https://github.com/junaire/test-solidity-fetch-content)
Signed-off-by: Jun Zhang <jun@junz.org>
CMake defaults to C *and* C++ toolchain, in case nothing has been specified.
This means that cmake always checks for both, which is more than needed.
This PR cuts off C toolchain requirement from /CMakeLists.txt and ensures that we
don't pass along any `..._C_...` variables in EthCompilerSettings.cake nor jsoncpp.cmake.
According to cmake documents, we cannot assume CMAKE_INSTALL_LIBDIR is a
relative path. This commit fixes the "no rule to make libjsoncpp.a"
error by passing -DCMAKE_INSTALL_LIBDIR=lib to jsoncpp external project.
When building on Debian/Ubuntu with install prefix /usr (e.g. in PPA builds) the CMAKE_INSTALL_LIBDIR is resolved to lib/x86_64-linux-gnu. For jsoncpp external project this is never the case because the install prefix is not /usr. Remove multiarch part from libdir if there.
This copies jsoncpp.cmake from ethereum/cpp-dependencies repo and adds BUILD_BYPRODUCT information to ExternalProject configuration (required by Ninja).
