The first method uses the set function: set(CMAKE_ARGS '$. We found two ways to add a new argument pair to the CMAKE_ARGS of the external project. Next, the new library target is linked to the executable target using targetlinklibraries(). From which, the arguments in the form -Dname:type=value are passed to the CMake command line and cannot be changed by the user. To make use of the new library we will add an addsubdirectory() call in the top-level CMakeLists.txt file so that the library will get built. Recently, we wanted to pass a new cached value to an external project in CMake via the CMAKE_ARGS variable.ĬMAKE_ARGS holds various types of arguments. Both methods are supported by vcpkg.20 November 2017 in Programming tagged cmake / CMAKE_ARGS / ExternalProject_Add / list / set by Tux

Or you can just include their toolchain file at the bottom of yours. Regarding the use vcpkg and wanting to use your own toolchain file, vcpkg provides the VCPKG_CHAINLOAD_TOOLCHAIN_FILE variable for that. The CMAKEPREFIXPATH environment variable may be set to a list of directories specifying installation prefixes to be searched by the findpackage(), findprogram(), findlibrary(), findfile(), and findpath() commands. I think the project can and should set it, but that can be done in a way that the user can still override it if they need to build everything with a higher language standard. This is a CMake Environment Variable.Its initial value is taken from the calling process environment. I understand the arguments for and against. Personally, I see that as something the project should set, but some people hold strong views that it should be under the user’s control. The CMAKE_STANDARD flag is more contentious. For those things, use either the directory or target property manipulation commands like add_compile_options(), add_link_options(), target_compile_options() or target_link_options().

Consider very carefully if this is really what you want to do before you commit to this approach.Īvoid setting CMAKE_FLAGS, CMAKE_FLAGS_, CMAKE_LINKER_FLAGS or CMAKE_LINKER_FLAGS_ variables in the project. The list subcommands APPEND, INSERT, FILTER, PREPEND, POPBACK, POPFRONT, REMOVEAT, REMOVEITEM, REMOVEDUPLICATES, REVERSE and SORT may create new. It gets much worse if you start mixing in generator expressions, etc. A couple variations: Instead, you can just conditionally append the OpenMP::OpenMPCXX target: targetlinklibraries(myapp PRIVATE OpenMP::OpenMPCXX) as consecutive calls to targetlinklibraries for the same target will append items in the order called. It’s also quite fragile, because you’re assuming contents of those directory properties. That’s the tradeoff to using this approach. or link error (added source file not compiled). This assumes you want to remove those options for all targets in that CMakeLists.txt file’s directory scope. source files without editing the CMakeLists.txt file directly. By default GLOBRECURSE omits directories from result list.

) copies the elements specified with the list of indexes to the variable. list of source files from your source tree.

This would protect from accidental collision with names in outer scope. BTW, it is better to initialize list-variables using set(). Also, you can delimit A-related variables ('foo') from other ones ('bar'). The following cmakeminimumrequired(VERSION 2. As required by CMake, the items are separated by semicolons.

If you’ve set a common set of options at the top level, you could search for those specific options in the COMPILE_OPTIONS directory property in a particular target’s CMakeLists.txt and remove them from that property. The following modes are available: list(LENGTH ) counts the elements in the variable and stores the result in the variable. Your pseudo code with METALIST variable becomes worked after simple replacement metalist with list command. I would like to loop over list of items, given in a string.

That said, there may be scenarios where that is justified (and I have had to do this before myself).

If you need to leave out some of those options for a specific target, then that suggests those flags shouldn’t have been applied project-wide to begin with. If the project needs to add flags project-wide, it can use add_compile_options() from the top level CMakeLists.txt instead. Returns true if other is equal to this list otherwise returns false. See the syntax, options and examples of list (APPEND, INSERT, FILTER, PREPEND, etc.) subcommands. Leave variables like those for the user to manipulate. Learn how to use the list command to operate on lists of strings in CMake. Due either the compiler or the app supplied CMakeLists.txt C++11 support isnt detected by cmake even though it is supported and the application requires it. Don’t modify CMAKE_CXX_FLAGS in your project. I am wondering if it is possible to append to inferred variables when calling cmake.

Cmake list append