llvm-project

1b1ed4f2 - [LifetimeSafety] Overhaul CFG and analysis to also work with trivially destructed temporary objects (#177985)

[LifetimeSafety] Overhaul CFG and analysis to also work with trivially destructed temporary objects (#177985) Change summary: Modification to CFG: 1. Added `CFGFullExprCleanup` which has a pointer to `BumpVector<const MaterializeTemporaryExpr *>` to track all MTE that **might** (in the sense that we take union on branches) be spawned by an `ExprWithCleanups` 2. Modified logic in `CFGBuilder` to appropriately insert this marker. It inserts the marker primarily via `CFGBuilder::VisitExprWithCleanups`, and also `CFGBuilder::addInitializer` and `CFGBuilder::VisitDeclSubExpr` as these bypass visiting the `ExprWithCleanups`. The bump vector is allocated appropriately using the bump allocator of the CFG to respect its lifetime rules. 3. Visiting to track the temporaries is done in `CFGBuilder::VisitForTemporaries`. Behaviour is modulated via the `BuildOpts` so as to enable tracking only when necessary. The encountered non-lifetime extended MTE are stored in a small vector member of `TempDtorContext`. Modification to analysis: 1. Logic to issue the loans remains mostly the same, with the caveat that we now **always** issue a loan to any MTE that expires at the end of full expression. 2. Introduced `handleFullExprCleanup` to replace `handleTemporaryDtor`. It loops through all active loans, expiring them if the path matches an MTE in the `CFGFullExprCleanup` node's `ExpiringMTEs`. Fixes: #175893 #178159