Yes, it's a simple language. That's why there are no safe guards around INT_MAX + 1, or variants of that.

You can add two numbers. If the operands are signed you just need to check the operands before the addition to make sure you won't cause an overflow.

Which of course cannot be done portably except by drastic restrictions like "never add a number greater than MAXINT / 2 and never multiply a number greater than sqrt(MAXINT)".

Soon™ we will have ckd_add etc. in the standard for this sort of thing, after several decades finally exposing functionality that any non-exotic CPU provides.

Except RISC-V, because RISC-V. Or, I expect, because they must have gathered statistics from a big chunk of real-world (mostly C and -compatible) code and got a bit fat nothing for the usage of the overflow flag—not because it's useless but precisely because you couldn't get at it from (compiler-independent) C.

Overflow isn't the only flag RISC-V doesn't have.

If floating point extensions aren't present, there aren't even flags.

Since we're talking about implementing a compiler that merely uses C/++ as a convenient intermediate representation, it doesn't matter much.