Let's way that warnings are very important, they cause noise, so such noise should be deserved for instances that are really common mistakes among the population of programmers that have some clue. There are many errors like the one above that can be made by clueless programmers for which you can't emit a warning at all, like misusing postfixed/prefixed increment operators or alike.
The vast majority of people writing C that I've seen in the past 20 years are occasional C programmers. We write in higher-level languages, and occasionally drop down into C to troubleshoot a library we're using. I haven't been a full-time C programmer since late last century. I see C code these days and think "huh, so that's valid in C now".
I get that you are a full-time C programmer, but unless you're volunteering to take on all my C troubleshooting work, this seems almost punitive. Like building a balcony with no railing, because nobody would just walk off a ledge -- and yet, sadly, professionals still die from falls.
To say that all such people are "clueless", regardless of skill or training or experience, is to fall back on the old test pilot mentality: the good survive, therefore, if you didn't survive, you (retroactively) must not have had The Right Stuff after all.
Joel Spolsky explained the reasoning more eloquently than I could:
"Now, even without going through with this experiment, I can state with some confidence that some of the users will simply fail to complete the task, or will take an extraordinary amount of time doing it. I don’t mean to say that these users are stupid. Quite the contrary, they are probably highly intelligent, or maybe they are accomplished athletes, but vis-à-vis your program, they are just not applying all of their motor skills and brain cells to the usage of your program. You’re only getting about 30% of their attention, so you have to make do with a user who, from inside the computer, does not appear to be playing with a full deck."
I trust myself and the people I work with, but I still wear a hardhat when they're working overhead, and I tie all my tools to my belt when I'm working at height. It's the clueless people who don't learn from the mistakes of the past.
Let me clarify - you're saying that just because we can't catch all programming mistakes means we shouldn't bother catching any, even though this is a pretty solid example of one that would be worthwhile and easy to do?
Nope, I think that to catch trivial errors like that is mostly unhelpful, what bothers me about that is that could emit a warning in perfectly ok code, for instance as a result of a post-processing that maps symbols to literal values. Given that 3^5 will never be the result of some programing genuine mistake, but means not knowing the language, I think it is worse to create issues to people that know what they are doing (emitting a useless warning), than trying to advice people not knowing the basic of the language. Anyway such mistake will be realized very soon by the inexperienced programmer.
