[PATCH] D100852: [analyzer] Track leaking object through stores

[Valeriy Savchenko via Phabricator via cfe-commits]

vsavchenko added a comment.

In D100852#2704282 <https://reviews.llvm.org/D100852#2704282>, @NoQ wrote:

> I think this is already way better than before. I see that `OSDynamicCast` isn't supported yet and we seem to hit the same wall as D97183 <https://reviews.llvm.org/D97183> because inter-operation between `trackExpressionValue` and the checkers isn't implemented yet.

Let's say that `OSDynamicCast` isn't **fully** supported.  If we have a chain of bindings `var1 -> var2 -> ... -> varN` and `varM -> varM+1` is a dynamic cast assignment, we will create a note that `varM+1` is assigned/initialized here (as you can see in tests), but not further down the chain. `check_dynamic_cast_alias_intermediate` is a good example here.
We still have work to do, but in the most common case where `var1 -> var2` is the whole chain, we work as expected.



================
Comment at: clang/lib/StaticAnalyzer/Checkers/RetainCountChecker/RetainCountDiagnostics.cpp:636
     if (isa<NonParamVarRegion>(R))
-      Result.push_back(R);
+      Result.emplace_back(R, Val);
 
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NoQ wrote:
> Because we already know that `Val.getAsLocSymbol()` is equal to `Sym`, we can be certain that `Val` is either a `&SymRegion{Sym}` (i.e., literally this symbol in its pristine representation) or, in some rare cases, a `LocAsInteger` over that (which is a case i'm not sure we even want to handle). I dunno if we really need to return it here. Maybe it's easier to re-construct it in place as `SValBuilder.makeLoc(Sym)`.
Oh, that was my original solution, but it doesn't work for dynamic casts.
This check compares symbols, but `FindLastStore` compares `SVal`s.  `&Derived{&SymRegion}` is not the same as `&SymRegion` and we fail.
So, instead of hacking on the result from `SValBuilder` trying to make something that will indeed match the last stored value, I save that last stored value here, so we're guaranteed that `FindLastStore` will work as intended.


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Comment at: clang/lib/StaticAnalyzer/Checkers/RetainCountChecker/RetainCountDiagnostics.cpp:978
+
+    if (auto KV = AllVarBindings[0].second.getAs<KnownSVal>())
+      // Because 'AllocBindingToReport' is not the the same as
----------------
NoQ wrote:
> In particular, this check is always true and you can use `castAs`.
Yep, makes sense!


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https://reviews.llvm.org/D100852