[NFC][Clang] Fix static analyzer concern about null value dereference

[tahonermann]

Looks good to me!

[steakhal]

Hmm. I guess the assertion is to silence some tool. And I think actually that function might very well also return null in some cases.
Why do you think it cannot or at least should not return null in your context? I couldn't infer this from the context, neither from the description of this patch.

Without that, I would prefer an if to guard the code, instead of asserting this.

clang/lib/StaticAnalyzer/Checkers/FuchsiaHandleChecker.cpp

657

I think there is a typo in the word statement.

[steakhal]

If getStmtForDiagnostics() in general, never returns null, then shouldn't we mark the API with an appropriate attribute?

[eandrews]

In D157888#4586126, @steakhal wrote:

Hmm. I guess the assertion is to silence some tool. And I think actually that function might very well also return null in some cases.
Why do you think it cannot or at least should not return null in your context? I couldn't infer this from the context, neither from the description of this patch.

Without that, I would prefer an if to guard the code, instead of asserting this.

createBegin() has a call to getValidSourceLocation() which dereferences this Statement. So in this context Statement cannot be null.

If getStmtForDiagnostics() in general, never returns null, then shouldn't we mark the API with an appropriate attribute?

getStmtForDiagnostics() explicitly returns nullptr when none of the cases for ProgramPoint listed in the function are met. So I am not sure if we can just assume this function should never return null.

[eandrews]

clang/lib/StaticAnalyzer/Checkers/FuchsiaHandleChecker.cpp

657

Thanks for the review. I corrected this in the commit.

clang/lib/StaticAnalyzer/Checkers/FuchsiaHandleChecker.cpp

void FuchsiaHandleChecker::reportBug(SymbolRef Sym, ExplodedNode *ErrorNode,
                                      const BugType &Type, StringRef Msg) const {
   if (!ErrorNode)
     return;
 
   std::unique_ptr<PathSensitiveBugReport> R;
   if (Type.isSuppressOnSink()) {
     const ExplodedNode *AcquireNode = getAcquireSite(ErrorNode, Sym, C);
     if (AcquireNode) {
+      const Stmt *S = AcquireNode->getStmtForDiagnostics();
+      assert(S && "Statement cannot be null.");
       PathDiagnosticLocation LocUsedForUniqueing =
           PathDiagnosticLocation::createBegin(
-              AcquireNode->getStmtForDiagnostics(), C.getSourceManager(),
-              AcquireNode->getLocationContext());
+              S, C.getSourceManager(), AcquireNode->getLocationContext());
 
       R = std::make_unique<PathSensitiveBugReport>(
           Type, Msg, ErrorNode, LocUsedForUniqueing,
           AcquireNode->getLocationContext()->getDecl());
     }
   }
   if (!R)
     R = std::make_unique<PathSensitiveBugReport>(Type, Msg, ErrorNode);