[PATCH] D99714: [clang][Analyzer] Handle flexible arrays better in ArrayBoundV2 checker.

[Gabor Marton via Phabricator via cfe-commits]

martong added a comment.

In D99714#2663677 <https://reviews.llvm.org/D99714#2663677>, @balazske wrote:

> It works not reliable for all data types. If `char` is used instead of `int` (in the test), the allocated size may be larger than the intended size of the array, probably because memory alignment adjustments. In the following case it is possible to index "past the end" of the array for some first indices (until 12?).
>
>   struct S {
>     int n;
>     char x;
>     char s[];
>   };



> struct S *s = (struct S *)malloc(sizeof(struct S) + 10);
> s.s[12] = 12;
>
>   

Then I suppose we have to consider the alignment info as well. Perhaps you could reuse some parts of the PlacementNewChecker's alignment checking implementation? (see https://github.com/llvm/llvm-project/blob/main/clang/lib/StaticAnalyzer/Checkers/CheckPlacementNew.cpp#L176 ) I'd do that only in second follow-up patch, because that is going to complicate things.


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