Why does linking a free-standing C program with gcc result in an undefined reference to `__gxx_personality_v0`?

When compiling and linking a free-standing C program using gcc, a linker error can occur due to an undefined reference to __gxx_personality_v0. To understand the purpose of this symbol, let's explore its role in the context of the error message you provided.

What is the role of __gxx_personality_v0?

The symbol __gxx_personality_v0 is utilized in the stack unwinding tables, which are visible in the assembly output of stack unwinding. According to the Itanium C ABI, it is referred to as the Personality Routine.

In the absence of exceptions, defining this symbol as a global NULL void pointer will "work" because no exceptions are being thrown. However, attempting to throw an exception will result in unexpected behavior.

Alternative solutions:

• Disable exceptions using -fno-exceptions.
• If RTTI is also not being used, add -fno-rtti.
• For exception-using programs, compile with g instead of gcc, which automatically includes the necessary library (-lstdc ).

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