[PATCH] D120992: [analyzer] ReverseNull: New checker to warn for pointer value conditions, if the pointer value is unconditionally non-null

[Kristóf Umann via Phabricator via cfe-commits]

Szelethus added inline comments.


================
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:
> 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?


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  https://reviews.llvm.org/D120992/new/

https://reviews.llvm.org/D120992