Tweak null dereference diagnostics to give clearer diagnostics when
a null dereference results from a field access.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@99236 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Checker/DereferenceChecker.cpp b/lib/Checker/DereferenceChecker.cpp
index 0cbc408..dfd3b61 100644
--- a/lib/Checker/DereferenceChecker.cpp
+++ b/lib/Checker/DereferenceChecker.cpp
@@ -29,9 +29,9 @@
DereferenceChecker() : BT_null(0), BT_undef(0) {}
static void *getTag() { static int tag = 0; return &tag; }
void VisitLocation(CheckerContext &C, const Stmt *S, SVal location);
-
+
std::pair<ExplodedNode * const*, ExplodedNode * const*>
- getImplicitNodes() const {
+ getImplicitNodes() const {
return std::make_pair(ImplicitNullDerefNodes.data(),
ImplicitNullDerefNodes.data() +
ImplicitNullDerefNodes.size());
@@ -59,7 +59,7 @@
if (ExplodedNode *N = C.GenerateSink()) {
if (!BT_undef)
BT_undef = new BuiltinBug("Dereference of undefined pointer value");
-
+
EnhancedBugReport *report =
new EnhancedBugReport(*BT_undef, BT_undef->getDescription(), N);
report->addVisitorCreator(bugreporter::registerTrackNullOrUndefValue,
@@ -68,31 +68,32 @@
}
return;
}
-
+
DefinedOrUnknownSVal location = cast<DefinedOrUnknownSVal>(l);
-
- // Check for null dereferences.
+
+ // Check for null dereferences.
if (!isa<Loc>(location))
return;
-
+
const GRState *state = C.getState();
const GRState *notNullState, *nullState;
llvm::tie(notNullState, nullState) = state->Assume(location);
-
+
// The explicit NULL case.
if (nullState) {
- if (!notNullState) {
+ if (!notNullState) {
// Generate an error node.
ExplodedNode *N = C.GenerateSink(nullState);
if (!N)
return;
-
+
// We know that 'location' cannot be non-null. This is what
- // we call an "explicit" null dereference.
+ // we call an "explicit" null dereference.
if (!BT_null)
BT_null = new BuiltinBug("Dereference of null pointer");
-
+
llvm::SmallString<100> buf;
+ llvm::SmallVector<SourceRange, 2> Ranges;
switch (S->getStmtClass()) {
case Stmt::UnaryOperatorClass: {
@@ -101,10 +102,26 @@
if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(SU)) {
if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) {
llvm::raw_svector_ostream os(buf);
- os << "Dereference of null pointer loaded from variable '"
- << VD->getName() << '\'';
+ os << "Dereference of null pointer (loaded from variable '"
+ << VD->getName() << "')";
+ Ranges.push_back(DR->getSourceRange());
}
}
+ break;
+ }
+ case Stmt::MemberExprClass: {
+ const MemberExpr *M = cast<MemberExpr>(S);
+ if (M->isArrow())
+ if (DeclRefExpr *DR =
+ dyn_cast<DeclRefExpr>(M->getBase()->IgnoreParenCasts())) {
+ if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) {
+ llvm::raw_svector_ostream os(buf);
+ os << "Field access results in a dereference of a null pointer "
+ "(loaded from variable '" << VD->getName() << "')";
+ Ranges.push_back(M->getBase()->getSourceRange());
+ }
+ }
+ break;
}
default:
break;
@@ -117,19 +134,23 @@
report->addVisitorCreator(bugreporter::registerTrackNullOrUndefValue,
bugreporter::GetDerefExpr(N));
-
+
+ for (llvm::SmallVectorImpl<SourceRange>::iterator
+ I = Ranges.begin(), E = Ranges.end(); I!=E; ++I)
+ report->addRange(*I);
+
C.EmitReport(report);
return;
}
else {
// Otherwise, we have the case where the location could either be
// null or not-null. Record the error node as an "implicit" null
- // dereference.
+ // dereference.
if (ExplodedNode *N = C.GenerateSink(nullState))
ImplicitNullDerefNodes.push_back(N);
}
}
-
+
// From this point forward, we know that the location is not null.
C.addTransition(notNullState);
}