All the weird stuff I have read about C or C++ doing over the years could be summed up with “Well… don’t do that.”

Like almost without fail. I can’t even think of how you’d end up in a scenario like this because a compiler would complain before letting you use an undefined implicit declaration.

"because the problematic behavior was removed from the standard over 27 years ago, we'll never have closure on what the intended interpretation is."

Obsolete standard turns out to be insufficiently strict, news at 11.

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That's a nice bit of understated 90s design right there