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C++: Improve comment based on PR feedback.

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Mathias Vorreiter Pedersen
2024-04-10 14:55:29 +01:00
parent a7c98e3d94
commit 1ae22d0781
1 changed files with 12 additions and 8 deletions
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20
cpp/ql/lib/semmle/code/cpp/models/implementations/Iterator.qll
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@@ -141,10 +141,12 @@ private class IteratorCrementNonMemberOperatorModel extends IteratorCrementNonMe
}
override predicate hasSpecificWriteSideEffect(ParameterIndex i, boolean buffer, boolean mustWrite) {
// `buffer` must be `true` or `mustWrite` must be `false` to ensure that
// the IR alias analysis doesn't think that `it++` doesn't completely override
// the value of the iterator. Ideally, the IR alias analysis shouldn't deal with
// iterators, but this is necessary for taintflow to get any results in our iterator tests.
// We have two choices here: either `buffer` must be `true` or `mustWrite`
// must be `false` to ensure that the IR alias analysis doesn't think that
// `it++` completely override the value of the iterator.
// We choose `mustWrite` must be `false`. In that case, the value of
// `buffer` isn't super important (it just decides which kind of read side
// effect will be emitted).
i = 0 and buffer = false and mustWrite = false
}
@@ -193,10 +195,12 @@ private class IteratorCrementMemberOperatorModel extends IteratorCrementMemberOp
}
override predicate hasSpecificWriteSideEffect(ParameterIndex i, boolean buffer, boolean mustWrite) {
// `buffer` must be `true` or `mustWrite` must be `false` to ensure that
// the IR alias analysis doesn't think that `it++` doesn't completely override
// the value of the iterator. Ideally, the IR alias analysis shouldn't deal with
// iterators, but this is necessary for taintflow to get any results in our iterator tests.
// We have two choices here: either `buffer` must be `true` or `mustWrite`
// must be `false` to ensure that the IR alias analysis doesn't think that
// `it++` completely override the value of the iterator.
// We choose `mustWrite` must be `false`. In that case, the value of
// `buffer` isn't super important (it just decides which kind of read side
// effect will be emitted).
i = -1 and buffer = false and mustWrite = false
}