Why does flowing off the end of a non-void function without returning a value not produce a compiler error?

Question

Ever since I realized many years ago, that this doesn\'t produce an error by default (in GCC at least), I\'ve always wondered why?

I understand that you can issue co

Answer 1

It is legal under C/C++ to not return from a function that claims to return something. There are a number of use cases, such as calling exit(-1), or a function that calls it or throws an exception.

The compiler is not going to reject legal C++ even if it leads to UB if you are asking it not to. In particular, you are asking for no warnings to be generated. (Gcc still turns on some by default, but when added those seem to align with new features not new warnings for old features)

Changing the default no-arg gcc to emit some warnings could be a breaking change for existing scripts or make systems. Well designed ones either -Wall and deal with warnings, or toggle individual warnings.

Learning to use a C++ tool chain is a barrier to learning to be a C++ programmer, but C++ tool chains are typically written by and for experts.