Just the integer promotion rules are more complex than many languages' entire parser. And undefined behaviour makes the language practically impossible to learn, because there's simply no way to confirm the answer to any question you have about the language (other than "submit a DR and wait a few years for the answer to be published" - even the people who wrote the standard are confidently wrong about what it says, all the time) - you can form a hypothesis about how the language works, write a program to test this hypothesis, observe that the result is what you thought it would be - and you've learnt nothing, because your program was almost certainly undefined behaviour under a strict enough reading of the standard.
I wasn't aware that it is that critical. I have been doing C projects of all sizes and on different platforms and with different toolchains for forty years, including many where the same code runs on different platforms and is built with different toolchains, and I have never come across an undefined behavior for which there was no practical work-around in reasonable time. I have also never seen a language specification that answers all questions, not even Pascal or Ada. I agree that implicit conversions are an unfortunate feature of C, but I think the same about all languages where you can easily assign floating point to integer variables (or vice versa), for example. Cross-toolchain and cross-platform experiments are a constant activity with all the programming languages I use.
> I have never come across an undefined behavior for which there was no practical work-around in reasonable time.
How would you know? You don't generally find out until a newer compiler release breaks your code.
> I have also never seen a language specification that answers all questions, not even Pascal or Ada.
Maybe, but I haven't see "upgrade your compiler, get a new security bug" be defended so aggressively in other languages. Probably more cultural than legalistic - obviously "the implementation is the spec" has its problems, but most languages commit to not breaking behaviour that most code relies on, even if that behaviour isn't actually written in the spec, which means that in practice the language (the social artifact) is possible to learn in a way that C isn't.
> I agree that implicit conversions are an unfortunate feature of C, but I think the same about all languages where you can easily assign floating point to integer variables (or vice versa), for example.
So don't use those languages either then?
> Cross-toolchain and cross-platform experiments are a constant activity with all the programming languages I use.
Sounds pretty unpleasant, I practically never need to do that.
