[clang] [analyzer] Trust base to derived casts for dynamic types (PR #69057)

[Gábor Horváth via cfe-commits]

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@@ -392,19 +393,26 @@ void DynamicTypePropagation::checkPostCall(const CallEvent &Call,
   }
 }
 
-/// TODO: Handle explicit casts.
-///       Handle C++ casts.
-///
-/// Precondition: the cast is between ObjCObjectPointers.
 ExplodedNode *DynamicTypePropagation::dynamicTypePropagationOnCasts(
     const CastExpr *CE, ProgramStateRef &State, CheckerContext &C) const {
   // We only track type info for regions.
   const MemRegion *ToR = C.getSVal(CE).getAsRegion();
   if (!ToR)
     return C.getPredecessor();
 
-  if (isa<ExplicitCastExpr>(CE))
+  if (CE->getCastKind() == CK_BaseToDerived) {
+    bool CastSucceeds = true;
+    QualType FromTy = CE->getSubExpr()->getType();
+    QualType ToTy = CE->getType();
+    ToR = ToR->StripCasts(/*StripBaseAndDerivedCasts=*/true);
+    State = setDynamicTypeAndCastInfo(State, ToR, FromTy, ToTy, CastSucceeds);
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Xazax-hun wrote:

The value `true` could be inlined with a comment. 

https://github.com/llvm/llvm-project/pull/69057