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Comment by e3b0c | Hacker News Reader

I don't think bounds checking can be done at compile-time, especially in C/C++.

Not in the general case.

    char x[4];
    printf("%c", x[4]);

That's pretty easy to detect.

here you're talking about compile time bound check _elimination_, i.e. statically determine when you can remove a runtime bound check which would have been added by the compiler. I think e3b0c was talking about completely static bound checks.

No.

We can look at the example given above and clearly know/prove that the access is out of bounds. ie: a C compiler could emit a diagnostic (or decide it's undefined behavior and treat it as unreachable).

There aren't any bounds checks above to eliminate.

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