Undefined Reference to Virtual Table for "BarelySocket"

Encountering the "undefined reference to vtable" error in Qt indicates a missing implementation or declaration for a virtual method in class "BarelySocket." However, the provided code claims to have no virtual methods.

Cause and Resolution:

The error message suggests that a virtual method is being called without a corresponding definition in the class. However, according to the given header file, there are no virtual methods declared.

It's crucial to note that any time the Q_OBJECT macro is used, it's necessary to re-run qmake (Qt's build system) to generate the necessary metadata for the class. This step ensures that the virtual table is correctly defined.

Solution:

Re-running qmake using the following command within the Qt Creator IDE or command prompt should resolve the issue:

qmake

After running qmake, the project should be re-built to incorporate the updated metadata. Once the qmake and build processes are complete, the linker should correctly identify the virtual table and the error message should disappear.

Remember, it's essential to re-run qmake whenever new Q_OBJECT macros are added or removed from classes to avoid any future virtual table-related errors.