> On the one hand it looks like relying on behaviour that is correct now but may not be so in the future.

> Use a decent IDE that looks out for it if you need reminding about this class of bug.

And when your next environment/plugin/employer's setup changes or doesn't offer this warning? Or the day that getting your critical system back up ASAP leaves you no choice but to SSH in from your phone and edit your source in Nano?

Learning and practicing defensive programming as a professional programmer is like defensive driving for a taxi driver, or survival skills for a long-distance hiker. It's a part of what someone who considers themselves a serious professional should maintain.

Relying on a 'decent IDE' to manage your code quality for you is an excellent way to blunt your skills. I'm not saying we should all throw IDEs away or turn off their warnings, but to rely on them is an awful substitute for maintaining good practice. Granted, crossing every t and dotting every i is much, much harder in C than most other languages, but every compiler warning you have to hunt down and fix is another little slice of your day shaved off and gone.