[clang] [StaticAnalyzer] Fix state update in VisitObjCForCollectionStmt (PR #124477)

[Donát Nagy via cfe-commits]

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@@ -124,24 +124,26 @@ void ExprEngine::VisitObjCForCollectionStmt(const ObjCForCollectionStmt *S,
 
   bool isContainerNull = state->isNull(collectionV).isConstrainedTrue();
 
-  ExplodedNodeSet dstLocation;
-  evalLocation(dstLocation, S, elem, Pred, state, elementV, false);
+  ExplodedNodeSet NewPreds; // evalLocation may alter `Pred`
+  evalLocation(NewPreds, S, elem, Pred, state, elementV, false);
 
-  ExplodedNodeSet Tmp;
-  StmtNodeBuilder Bldr(Pred, Tmp, *currBldrCtx);
+  for (ExplodedNode *Pred : NewPreds) {
+    ExplodedNodeSet PredSingleton{Pred}, Tmp;
+    StmtNodeBuilder Bldr(Pred, Tmp, *currBldrCtx);
 
-  if (!isContainerNull)
-    populateObjCForDestinationSet(dstLocation, svalBuilder, S, elem, elementV,
-                                  SymMgr, currBldrCtx, Bldr,
-                                  /*hasElements=*/true);
+    if (!isContainerNull)
+      populateObjCForDestinationSet(PredSingleton, svalBuilder, S, elem,
+                                    elementV, SymMgr, currBldrCtx, Bldr,
+                                    /*hasElements=*/true);
 
-  populateObjCForDestinationSet(dstLocation, svalBuilder, S, elem, elementV,
-                                SymMgr, currBldrCtx, Bldr,
-                                /*hasElements=*/false);
+    populateObjCForDestinationSet(PredSingleton, svalBuilder, S, elem, elementV,
+                                  SymMgr, currBldrCtx, Bldr,
+                                  /*hasElements=*/false);
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NagyDonat wrote:

> Can we do this in a separate NFC PR?

Of course, that's completely fine. Thanks in advance for implementing it! 

https://github.com/llvm/llvm-project/pull/124477