C compiler in C++ project - do I need to specify it?

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In my C++ project I've observed that when I remove C compiler from toolchain executables then the project won't compile, saying: "another_precompiled - Debug": The compiler's setup is invalid so Code::Blocks cannot find/run the compiler. Probably the toolchain path within the compiler options is not setup correctly?! Skipping...
Why do I have to specify C compiler for C++ project?
Thanks