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I believe the committee's intent was, as they stated, to ‘codify existing practice’. That means that the compiler generates code for the statement as written (i

by kps 7y ago

I believe the committee's intent was, as they stated, to ‘codify existing practice’. That means that the compiler generates code for the statement as written (in this case, a store into location foo+10) and what happens when it runs is up to the machine and not the compiler's problem. At the time ANSI C was under way, I was working on a commercial C compiler and following developments closely. I don't think anyone anticipated what ‘undefined behavior’ would turn into.

Rusky 7y ago
The problem with that approach is it inhibits a lot of perfectly-sensible optimizations. If you force the compiler to leave it up to the machine, you force it to preserve the same stack layout, the same memory write, and the same execution order relative to everything else. You basically forbid it from working with an execution model at any level higher than "a giant array of bytes," because now you have to preserve the naive behavior of that giant array of bytes. But this is not really useful for correct programs. The committee's intent may have (accidentally, indirectly) been to codify compilers that do very little optimization, but that doesn't mean it was a good idea.