[scan-build] fix warnings emitted on Clang StaticAnalyzer code base

[apelete]

Summary

This patch fixes a few "Logic error" warnings of the type "Called c++
object pointer is null" reported by Clang Static Analyzer on the
following files:

• lib/StaticAnalyzer/Checkers/NullabilityChecker.cpp,
• lib/StaticAnalyzer/Core/PlistDiagnostics.cpp.

Signed-off-by: Apelete Seketeli <[e-mail]>

[dblaikie]

lib/StaticAnalyzer/Core/PlistDiagnostics.cpp

298

This assertion seems to be equivalent to replacing the prior 'if' with an assertion of the same condition, no? Is that correct? (& if it is, we should just do that)

[apelete]

lib/StaticAnalyzer/Core/PlistDiagnostics.cpp

298

You're right, I overlooked the simplification.
Will fix in next revision.

[apelete]

[scan-build] fix warnings emitted on Clang StaticAnalyzer code base

• lib/StaticAnalyzer/Core/PlistDiagnostics.cpp: factorize assert and check on '!Diags.empty' condition.

[zaks.anna]

lib/StaticAnalyzer/Checkers/NullabilityChecker.cpp

686

This conditional will assert if:

assert(Arg < NumArgs && "Arg access out of range!");

So removing this conditional will assert in the same cases as the assert you are adding.

696

Asserting might not be the right thing to do here.

lib/StaticAnalyzer/Checkers/NullabilityChecker.cpp

void NullabilityChecker::checkPreCall(const CallEvent &Call,
   ProgramStateRef OrigState = State;
 
   unsigned Idx = 0;
   for (const ParmVarDecl *Param : Call.parameters()) {
     if (Param->isParameterPack())
       break;
 
     const Expr *ArgExpr = nullptr;
     if (Idx < Call.getNumArgs())
       ArgExpr = Call.getArgExpr(Idx);
     auto ArgSVal = Call.getArgSVal(Idx++).getAs<DefinedOrUnknownSVal>();
     if (!ArgSVal)
       continue;
 
     if (!Param->getType()->isAnyPointerType() &&
         !Param->getType()->isReferenceType())
       continue;
 
+    assert(ArgExpr && "cannot get the type of a NULL expression");
+
     NullConstraint Nullness = getNullConstraint(*ArgSVal, State);
 
     Nullability RequiredNullability =
         getNullabilityAnnotation(Param->getType());
     Nullability ArgExprTypeLevelNullability =
         getNullabilityAnnotation(ArgExpr->getType());
 
     unsigned ParamIdx = Param->getFunctionScopeIndex() + 1;

lib/StaticAnalyzer/Core/PlistDiagnostics.cpp

void PlistDiagnostics::FlushDiagnosticsImpl(
                                     std::vector<const PathDiagnostic *> &Diags,
                                     FilesMade *filesMade) {
   // Build up a set of FIDs that we use by scanning the locations and
   // ranges of the diagnostics.
   FIDMap FM;
   SmallVector<FileID, 10> Fids;
   const SourceManager* SM = nullptr;
 
-  if (!Diags.empty())
-    SM = &Diags.front()->path.front()->getLocation().getManager();
+  assert(!Diags.empty() && "cannot iterate through empty PathDiagnostic");
 
-
   for (std::vector<const PathDiagnostic*>::iterator DI = Diags.begin(),
        DE = Diags.end(); DI != DE; ++DI) {
 
     const PathDiagnostic *D = *DI;
 
     SmallVector<const PathPieces *, 5> WorkList;
     WorkList.push_back(&D->path);