> There are edge-cases even there. Calling a function generated by a JIT compiler is undefined behaviour, but there's a gentleman's agreement that the compiler won't screw it up for you.
Though you're not writing C/C++ in that case. You're writing "C/C++ for that particular architecture, ABI, OS and compiler".
In general C/C++, if your code is correct every present and future, known and unknown compiler is supposed to generate a correct executable. If they don't, they have a bug. You can pretend to be smarter and go UB, but then the responsibility shifts on you, you have (in principle) to validate each compiler and environment and you can claim no bug on anybody other than you.
Sounds right. If you're doing floating-point work it's not generally a problem to assume that division by zero will result in NaN. Virtually all C and C++ compilers commit to this behaviour in the name of IEEE 754 compliance (even if the IEEE 754 compliance is incomplete).
Though you're not writing C/C++ in that case. You're writing "C/C++ for that particular architecture, ABI, OS and compiler".
In general C/C++, if your code is correct every present and future, known and unknown compiler is supposed to generate a correct executable. If they don't, they have a bug. You can pretend to be smarter and go UB, but then the responsibility shifts on you, you have (in principle) to validate each compiler and environment and you can claim no bug on anybody other than you.