paths.cmake

Jancy build system uses paths.cmake file as the main reference when it needs to find a certain tool or library. When a path is not specified, a fallback attempt to find it using find_package will be made.

This allows for out-of-the-box default build and at the same time provides a fine-grained control over locations of dependencies. Here in Tibbo, we have multiple versions of tools and libraries installed on the single build machine and at the same time, we are always in full control over which tool or library is going to be used when building a particular project.

paths.cmake files are cascading. It means, you can place one anywhere above the current directory and it will be found and used. From there you can chain-include the next paths.cmake and so on. This way you can specify some default locations for all your projects but still be able to override the paths for sub-projects.

Being machine-specific paths.cmake files are added to .gitignore and are never tracked in Git. Therefore, you need to write paths.cmake file as the very first step of the configuration process. So, what should be inside?

To answer this question, you need to check dependencies.cmake file. Inside this file, a variable called AXL_PATH_LIST contains all the paths that will be used during the build:

LUA_INC_DIR         # path to Lua C include directory
LUA_LIB_DIR         # path to Lua library directory
LUA_LIB_NAME        # name of Lua library (lua/lua51/lua52/lua53)
LLVM_INC_DIR        # path to LLVM include directory (list is OK)
LLVM_LIB_DIR        # path to LLVM library directory
LLVM_CMAKE_DIR      # path to LLVM CMake module directory
PCAP_INC_DIR        # (optional) path to Pcap include directory
PCAP_LIB_DIR        # (optional) path to Pcap library directory
LIBSSH2_INC_DIR     # (optional) path to LibSSH2 include directory
LIBSSH2_LIB_DIR     # (optional) path to LibSSH2 library directory
OPENSSL_INC_DIR     # (optional) path to OpenSSL include directory
OPENSSL_LIB_DIR     # (optional) path to OpenSSL library directory
QT_CMAKE_DIR        # (optional) path to QT CMake module directory
QT_DLL_DIR          # (optional) path to QT dynamic library directory (Windows only)
RAGEL_EXE           # path to Ragel executable
7Z_EXE              # path to 7-Zip executable
DOXYGEN_EXE         # (optional) path to Doxygen executable
DOXYREST_CMAKE_DIR  # (optional) path to Doxyrest CMake module directory
SPHINX_BUILD_EXE    # (optional) path to Sphinx compiler executable sphinx-build
PDFLATEX_EXE        # (optional) path to Latex-to-PDF compiler

Some dependencies may be auto-detected – on Unix systems installed libraries and tools will likely be found automatically. On Windows Jancy build system will automatically find tool executables if they are added to PATH (via where command).

But even when auto-detection works out-of-the-box, you can always use paths.cmake to fine-tune the location of a specific tool/library. I personally prefer to always specify all the paths explicitly.

You do need to specify LLVM paths (unless you build and install LLVM 3.4.2 and not the newer versions available in repositories).

On Windows, you will also need to specify paths to the required libraries – they are unlikely to be found automatically.

Sample paths.cmake on Linux:

set(LLVM_VERSION 3.4.2)

set(LLVM_INC_DIR  /home/vladimir/Develop/llvm/llvm-${LLVM_VERSION}/include)

if("${TARGET_CPU}" STREQUAL "amd64")
        set(LLVM_CMAKE_DIR  /home/vladimir/Develop/llvm/llvm-${LLVM_VERSION}/build/make-amd64/${CONFIGURATION}/share/llvm/cmake)
        set(LLVM_INC_DIR    ${LLVM_INC_DIR} /home/vladimir/Develop/llvm/llvm-${LLVM_VERSION}/build/make-amd64/${CONFIGURATION}/include)
        set(LLVM_LIB_DIR    /home/vladimir/Develop/llvm/llvm-${LLVM_VERSION}/build/make-amd64/${CONFIGURATION}/lib)
else()
        set(LLVM_CMAKE_DIR  /home/vladimir/Develop/llvm/llvm-${LLVM_VERSION}/build/make-x86/${CONFIGURATION}/share/llvm/cmake)
        set(LLVM_INC_DIR    ${LLVM_INC_DIR} /home/vladimir/Develop/llvm/llvm-${LLVM_VERSION}/build/make-x86/${CONFIGURATION}/include)
        set(LLVM_LIB_DIR    /home/vladimir/Develop/llvm/llvm-${LLVM_VERSION}/build/make-x86/${CONFIGURATION}/lib)
endif()

Sample paths.cmake on Windows:

set(LUA_VERSION   5.2.1)
set(LUA_LIB_NAME  lua52)
set(LLVM_VERSION  3.4.2)
set(RAGEL_VERSION 6.7)

set(7Z_EXE       "c:/Program Files/7-Zip/7z.exe")
set(PERL_EXE     c:/Develop/ActivePerl/bin/perl.exe)
set(RAGEL_EXE    c:/Develop/ragel/ragel-${RAGEL_VERSION}/ragel.exe)
set(LUA_INC_DIR  c:/Develop/lua/lua-${LUA_VERSION}/include)
set(LLVM_INC_DIR c:/Develop/llvm/llvm-${LLVM_VERSION}/include)

if("${TARGET_CPU}" STREQUAL "amd64")
        set(LUA_LIB_DIR    c:/Develop/lua/lua-${LUA_VERSION}/lib/amd64/${CONFIGURATION})
        set(LLVM_INC_DIR   ${LLVM_INC_DIR} c:/Develop/llvm/llvm-${LLVM_VERSION}/build/msvc10-amd64/include)
        set(LLVM_LIB_DIR   c:/Develop/llvm/llvm-${LLVM_VERSION}/build/msvc10-amd64/lib/${CONFIGURATION})
        set(LLVM_CMAKE_DIR c:/Develop/llvm/llvm-${LLVM_VERSION}/build/msvc10-amd64/share/llvm/cmake)
else()
        set(LUA_LIB_DIR    c:/Develop/lua/lua-${LUA_VERSION}/lib/x86/${CONFIGURATION})
        set(LLVM_INC_DIR   ${LLVM_INC_DIR} c:/Develop/llvm/llvm-${LLVM_VERSION}/build/msvc10/include)
        set(LLVM_LIB_DIR   c:/Develop/llvm/llvm-${LLVM_VERSION}/build/msvc10/lib/${CONFIGURATION})
        set(LLVM_CMAKE_DIR c:/Develop/llvm/llvm-${LLVM_VERSION}/build/msvc10/share/llvm/cmake)
endif()