NoQ added a comment.
This check checks must-properties/all-paths properties. This has to be a data
flow / CFG-based warning. I don't think there's a way around.
================
Comment at: clang/lib/StaticAnalyzer/Checkers/NullPtrInterferenceChecker.cpp:166
+/// child is a sink node.
+static bool unconditionallyLeadsHere(const ExplodedNode *N) {
+ size_t NonSinkNodeCount = llvm::count_if(
----------------
xazax.hun wrote:
> Szelethus wrote:
> > xazax.hun wrote:
> > > xazax.hun wrote:
> > > > Consider the following code snippet:
> > > > ```
> > > > void f(int *p, bool b)
> > > > {
> > > > if (b) {
> > > > *p = 4;
> > > > }
> > > > if (p) {
> > > > ...
> > > > }
> > > > }
> > > > ```
> > > >
> > > > I suspect that we would get a warning for the code above. I think
> > > > warning on the code above might be reasonable (the values of `b` and
> > > > `p` might be correlated but in some cases the analyzer has no way to
> > > > know this, probably some assertions could make the code clearer in that
> > > > case).
> > > >
> > > > My problem is with the wording of the error message.
> > > > The warning `Pointer is unconditionally non-null here` on the null
> > > > check is not true for the code above.
> > > Also, if the check would warn for the code snippet above, the note
> > > "suggest moving the condition here" would also be incorrect.
> > What if we demand that the the `CFGBlock` of the dereference must dominate
> > the `CFGBlock` of the condition point?
> I think it makes sense to warn both when the dereference dominates the null
> check, and when the null check post-dominates the dereference. We just want
> to give different error messages in those cases.
> What if we demand that the the CFGBlock of the dereference must dominate the
> CFGBlock of the condition point?
```lang=c
*p = 4;
if (b) {
p = bar();
}
if (p) {
...
}
```
Repository:
rG LLVM Github Monorepo
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https://reviews.llvm.org/D120992/new/
https://reviews.llvm.org/D120992
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