[PATCH] D101041: [analyzer] Find better description for tracked symbolic values

[Valeriy Savchenko via Phabricator via cfe-commits]

vsavchenko added inline comments.


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Comment at: clang/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp:1532
+      // Telling the user that the value of 'a' is assigned to 'c', while
+      // correct, can be confusing.
+      StoreManager::FindUniqueBinding FB(V.getAsLocSymbol());
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martong wrote:
> vsavchenko wrote:
> > martong wrote:
> > > So here, we have two or three bindings attached to `c`? `foo(b)` and `a` (and `b` as well) ?
> > > What is the guarantee that `FindUniqueBinding` will return with the correct one `foo(b)`? Seems like we iterate through an ImmutableMap (AVL tree) with `MemRegion*` keys. And the order of the iteration depends on pointer values. What I want to express, is that I don't see how do we find the correct binding, seems like we just find one, which might be the one we look for if we are lucky.
> > > 
> > > Perhaps we could have a lit test for this example?
> > Good idea, I should a test for that!
> > `FindUniqueBinding` does not only have a region, it also carries a flag checking if there are more than one binding.  `operator bool` then checks for both, thus guaranteeing that we won't choose random binding out of more than 1 - we won't choose at all.
> Yeah, I missed that about `FindUniqueBinding`. 
> 
> It's just side questions then: Could we handle multiple bindings by finding the 'last' binding and tracking that back?
> And in this example, what are the bindings for `c`?
Can you please elaborate on what you mean by 'last', like 'last used'?
As for `c`, you can see above that I'm looking for a node where 'c' is not bound to that value.  So, we start with the node where 'a', 'b', and 'c' all bound to symbolic value... let's say 'x'. I go up the graph to the point where 'c' is not bound to 'x' and there I look for unique binding for 'x'.  In that example, we won't find it because it has two: 'a' and 'b'.


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https://reviews.llvm.org/D101041