GoKawiilThis is my personal blog. The views expressed on these pages are mine alone and not those of my employer. This is not AI. All hallucinations are my own human ones.
If he had been a programmer, Cardinal Richelieu would have said “Give me six lines written by the hand of the most expert C programmer in the world, and I will find enough in them to trigger undefined behavior”.
Nobody can write correct C, or C++. And I say that as someone who’s written C and C++ on an almost daily basis for about 30 years. I listen to C++ podcasts. I watch C++ conference talks. I enjoy reading and writing C++.
C++ has served us well, but it’s 2026, and the environment of 1985 (C++) or 1972 (C) is not the environment of today.
I’m definitely not the first to say this. I remember reading a post by someone prominent about a decade ago saying that a good case can be made that use of C++ is a SOX violation. And while I was not onboard with the rest of their rant (nor their confusion about “its” vs “it’s”), I never disagreed about that point.
With time I found it to be more and more true. WAY more things are undefined behavior (UB) than you’d expect.
Everyone knows that double-free, use after free, accessing outside the bounds of an object (e.g. array), and accessing uninitialized memory is UB. After all, C/C++ is not a memory safe language. And yet we as an industry seem to be unable to stop making even those mistakes over and over.
But there’s more. More subtle. More illogical.
It’s not about optimizations
Some people seem to think that as long as they don’t compile with optimizations turned on, undefined behavior can’t hurt them. They believe that the compiler is somehow being deliberately hostile, going “AHA! UB! I can do whatever I want here!”, and without optimizations turned on it won’t.
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