This error typically arises during the configuration stage of a CMake project. It indicates that the build system cannot deduce the programming language used for linking the final executable or library. This often happens when source files are present, but CMake cannot associate them with a specific language compiler due to missing or incorrect language specifications within the `CMakeLists.txt` file. For instance, a project containing C++ source files might encounter this issue if the `project()` command does not specify C++ as a language, or if source files are added without using commands like `add_executable()` or `add_library()` which implicitly set the language based on file extensions.
Correct language determination is crucial for proper project compilation and linking. Without it, the build system cannot invoke the correct compiler or linker, leading to build failures. Accurately identifying the linker language allows CMake to set appropriate compiler flags, link libraries, and generate platform-specific build instructions. This ensures consistent and predictable build behavior across different systems and environments. Resolving this issue early in the project lifecycle prevents more complex problems down the line.
