[llvm-branch-commits] [clang] [LifetimeSafety] Support container interior paths and invalidations (PR #207523)

[Gábor Horváth via llvm-branch-commits]

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@@ -72,6 +72,18 @@ Loan *LoanManager::getOrCreateExtendedLoan(LoanID BaseLoanID,
   if (It != ExtensionCache.end())
     return It->second;
   const auto *BaseLoan = getLoan(BaseLoanID);
+
+  // Stop appending if Element is already in the path to prevent infinite path
+  // accumulation (divergence) on recursive types or casts.
+  //
+  // This sound over-approximation guarantees termination at the cost of
+  // precision. Conflating infinitely deep paths into a single truncated loan
+  // may cause false positives via spurious invalidations, but never causes
+  // false negatives.
+  for (const PathElement &E : BaseLoan->getAccessPath().getElements())
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Xazax-hun wrote:

Do we want to do this with `PathElement::getInterior()` as well? Imagine a vector of vectors like `std::vector<std::vector<int>> v;` and `v[1][1]`. Could we represent that?

https://github.com/llvm/llvm-project/pull/207523