[clang] [LifetimeSafety] Implement a basic use-after-free diagnostic (PR #149731)

[Gábor Horváth via cfe-commits]

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@@ -861,26 +911,29 @@ class ExpiredLoansAnalysis
     : public DataflowAnalysis<ExpiredLoansAnalysis, ExpiredLattice,
                               Direction::Forward> {
 
-  LoanSet::Factory &Factory;
+  ExpiredLoanMap::Factory &Factory;
 
 public:
   ExpiredLoansAnalysis(const CFG &C, AnalysisDeclContext &AC, FactManager &F,
                        LifetimeFactory &Factory)
-      : DataflowAnalysis(C, AC, F), Factory(Factory.LoanSetFactory) {}
+      : DataflowAnalysis(C, AC, F), Factory(Factory.ExpiredLoanMapFactory) {}
 
   using Base::transfer;
 
   StringRef getAnalysisName() const { return "ExpiredLoans"; }
 
-  Lattice getInitialState() { return Lattice(Factory.getEmptySet()); }
+  Lattice getInitialState() { return Lattice(Factory.getEmptyMap()); }
 
-  /// Merges two lattices by taking the union of the expired loan sets.
-  Lattice join(Lattice L1, Lattice L2) const {
-    return Lattice(utils::join(L1.Expired, L2.Expired, Factory));
+  /// Merges two lattices by taking the union of the two expired loans.
+  Lattice join(Lattice L1, Lattice L2) {
+    return Lattice(
+        utils::join(L1.Expired, L2.Expired, Factory,
+                    // Take any ExpireFact to join the values.
+                    [](const ExpireFact *F, const ExpireFact *) { return F; }));
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Xazax-hun wrote:

If we pick randomly, could that also influence how soon we reach a fixed point?

https://github.com/llvm/llvm-project/pull/149731