vrnithinkumar added inline comments.
================
Comment at: clang/lib/StaticAnalyzer/Checkers/SmartPtrModeling.cpp:408-412
+ SmallString<128> Msg;
+ llvm::raw_svector_ostream Out(Msg);
+ TagDetails.trackValidExpr(BR);
+ TagDetails.explainSmartPtrAction(Out);
+ return std::string(Out.str());
----------------
NoQ wrote:
> NoQ wrote:
> > vrnithinkumar wrote:
> > > NoQ wrote:
> > > > NoQ wrote:
> > > > > Ok, note that note tags are attached to nodes independently of bug
> > > > > reports; when the report is thrown, only then we know what are the
> > > > > smart pointers that should be explained.
> > > > >
> > > > > So there are two checks that you should do here:
> > > > >
> > > > > 1. Check that the bug report is emitted by your checker (eg., by
> > > > > comparing bug types). If not, don't add notes.
> > > > >
> > > > > 2. Check that the region about which the note speaks is related to
> > > > > your report (i.e., it's not a completely unrelated smart pointer).
> > > > > You can do that by marking the smart pointer as "interesting" (i.e.,
> > > > > `PathSensitiveBugReport::markIntersting()`) when you emit the report,
> > > > > and then in the lambda you check whether the smart pointer is
> > > > > interesting before you emit a note. Additionally, you can carry over
> > > > > interestingness when smart pointers are copied.
> > > > >
> > > > > This is what i was trying to accomplish with this code snippet that i
> > > > > included in the examples in the other comment:
> > > > > ```lang=c++
> > > > > if (&BR.getBugType() != &NullDereferenceBugType ||
> > > > > !R->isInteresting())
> > > > > return "";
> > > > > ```
> > > > (i strongly recommend having test cases for both of these issues)
> > > I was stuck on how to check the 2 cases from `SmartPtrModeling`.
> > >
> > > 1. I was not able to figure out how to access `NullDereferenceBugType`
> > > defined in the `SmartPtrChecker` in `SmartPtrModeling` to check
> > > `&BR.getBugType() != &NullDereferenceBugType`. Since
> > > `NullDereferenceBugType` is part of the `SmartPtrChecker` I could not
> > > access it from `PathSensitiveBugReport`. One way I figured out is to use
> > > `getCheckerName()` on BugType and compare the string. I feel this one as
> > > little hacky.
> > >
> > >
> > > 2. I got stuck on how will we implement the `!R->isInteresting()` in case
> > > of the bug report is added by some other checker on some other region.
> > > For below test case, bug report is added on a raw pointer by
> > > `CallAndMessageChecker` and the `!R->isInteresting()` will not satisfy
> > > and we will not be adding note tags where `unique_ptr` is released. I
> > > tried getting the LHS region for `A *AP = P.release();` assignment
> > > operation and check if the region is interesting but not sure whether its
> > > gonna work for some complex assignment cases.
> > >
> > > ```
> > > void derefOnReleasedNullRawPtr() {
> > > std::unique_ptr<A> P;
> > > A *AP = P.release(); // expected-note {{'AP' initialized to a null
> > > pointer value}}
> > > // expected-note@-1 {{Smart pointer 'P' is released and set to null}}
> > > AP->foo(); // expected-warning {{Called C++ object pointer is null
> > > [core.CallAndMessage]}}
> > > // expected-note@-1{{Called C++ object pointer is null}}
> > > }
> > > ```
> > > Since `NullDereferenceBugType` is part of the `SmartPtrChecker` I could
> > > not access it from `PathSensitiveBugReport`.
> >
> > You shouldn't be accessing it from the bug report, you should be accessing
> > it from the lambda. See the example code snippets in D84600#inline-779418
> >
> > > For below test case, bug report is added on a raw pointer by
> > > `CallAndMessageChecker` and the `!R->isInteresting()` will not satisfy
> > > and we will not be adding note tags where `unique_ptr` is released.
> >
> > That's an interesting question (no pun intended). The way i imagine this
> > working is: the note tag for `.release()` should try to figure out whether
> > the raw pointer is tracked and mark the smart pointer as interesting based
> > on that. If the raw pointer was a symbol that would have been easy (either
> > null dereference checker or `trackExpressionValue()` could mark it as
> > interesting). But for concrete null pointer this won't work.
> >
> > Maybe we should consider introducing interesting expressions. I.e., when
> > `trackExpressionValue()` reaches the call-expression `P.release()`, it has
> > to stop there. But if it also marked the call-expression as interesting,
> > the note tag provided by the checker could read that interestingness
> > information and act upon it by marking the smart pointer region as
> > interesting.
> > That's an interesting question
>
> I'd rather make a separate commit for this endeavor because it sounds pretty
> nasty.
> You shouldn't be accessing it from the bug report, you should be accessing it
> from the lambda. See the example code snippets in D84600#inline-779418
Sorry, I am still confused how will the lambda defined in the
`SmartPtrModeling` can capture the `NullDereferenceBugType` from
`SmartPtrChecker`?
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D84600/new/
https://reviews.llvm.org/D84600
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