[clang] [analyzer] Variant checker bindings (PR #87886)

[Donát Nagy via cfe-commits]

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@@ -681,6 +681,37 @@ ExprEngine::processRegionChanges(ProgramStateRef state,
                                                          LCtx, Call);
 }
 
+ProgramStateRef
+ExprEngine::handleCastingBeforeEvalCall(ExplodedNode *Pred, const Expr *Ex, 
+                                        SVal ValueToBind, ProgramStateRef State, StmtNodeBuilder* Bldr) const {
+  // TODO construct new Bldr if Bldr is null
+  bool DeleteAfter = false;
+  if (!Bldr) {
+    ExplodedNodeSet dstEvaluated;
+    Bldr = new StmtNodeBuilder(Pred, dstEvaluated, *currBldrCtx);
+    DeleteAfter = true;
+  }
+
+  if (auto *AsImplCast = dyn_cast_or_null<CastExpr>(Ex);
+      AsImplCast && AsImplCast->getSubExpr() && ValueToBind.isUndef()) {
+    const LocationContext *LCtx = Pred->getLocationContext();
+    if (!isa<CallExpr>(AsImplCast->getSubExpr())) {
+      return State;
+    }
+    SVal V = State->getSVal(AsImplCast->getSubExpr(), LCtx);
+    if (V.isUndef()) {
+      return State;
+    }
+    State = State->BindExpr(Ex, LCtx, V);
+    Bldr->generateNode(Ex, Pred, State);
+  }
+
+  if (DeleteAfter) {
+    delete Bldr;
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NagyDonat wrote:

There are _two_ early return branches where this `delete` is not reached. (I know that this is proof-of-concept and will be cleaned up before merging, but still...)

https://github.com/llvm/llvm-project/pull/87886