CMake v3.24 added a new feature for verifying that headers are self-contained, meaning they don’t rely on some other header having been included first. It builds on the file sets feature added in CMake v3.23. The new CMAKE_VERIFY_INTERFACE_HEADER_SETS variable can be set to true to enable the creation of targets that carry out these checks for appropriately defined file sets. It is intended to be a developer control, not something the project sets. For projects already using file sets to install their headers, it should be a very simple step for developers to enable these checks.