![]() ![]() Both files are supported in Visual Studio 2019 version 16.10 or later. CMakeUserPresets.json is for developers to save their own local builds. Use these files to drive CMake in Visual Studio and Visual Studio Code, in a continuous integration (CI) pipeline, and from the command line.ĬMakePresets.json is for saving project-wide builds. Pro Tip: If anything has gone wrong in your CMakeLists.txt, try looking in the cache! It's just a text file, but can be crazy helpful to figure out what's going on.CMake supports two files that allow users to specify common configure, build, and test options and share them with others: CMakePresets.json and CMakeUserPresets.json. It's been my experience that the above doesn't work as expected, because the add_library call doesn't seem to see the modification of the CXX flags. In particular, it appears that targets will always use target-affecting variables from the contained directory scope, not function scopes. It appears that not all scopes are created equal. There's a couple other random notes related to scoping I'd like to share. Mostly though, on the subject, I'll defer to the documentation! They're typed, as they interact with CMake's configuration GUI system), as well they tend to override normal variables (which makes a bit of sense). There's a little bit different about cache variables. They get written to a special file called CMakeCache.txt. Cache VariablesĬache variables are special ones that persist across runs of CMake. but not the current scope! So if you're going to want to read FOO back again, and see the updated value, you'll want to write to FOO without PARENT_SCOPE as well. Given that a scope has a reference to the scope it was copied from, it maybe isn't surprising that there's a way in CMake to affect the parent scope: set(FOO PARENT_SCOPE) The trick is realizing that the scope copying limits the impact of the changes you make to these variables Parent Scope If you don't realize, as i didn't, that scopes are copied-by-value, you may freak out at contaminating the build flags of other parts of a project. i.e despite the existence of target_compile_options, if you need to add compiler options only to a C++ compile, you'll still have to use CMAKE_CXX_FLAGS. A surprising amount of CMake configuration is still done only through what seem to be 'global' variables - despite the existence of more modern forms. This actually can be put to use to simplify your CMakeLists.txt. This means add_subdirectory and function inherit the scope from the point where they're called, but modification will not be reflected in the parent scope. Here's the trick to understanding scopes in CMake: Unlike other languages, where name lookup would walk up the tree of scopes, each new scope is a copy by value of the parent scope at that point.
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