Mystery error message : "expected identifier or ("

Screenshot attached.
After the #include statement but before the declaration of main I have red underwave indicating an error .
The popup explaining the error is included in the screenshot. It says "identifier expected or (" .
I don't understand the error, which may be my own lack of c understanding or not.
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Hello!
Do you still experience the problem after configuring CMakeLists.txt properly and reloading the project?