[clang] [LifetimeSafety] Suggest lifetime annotations (PR #169767)

[Kashika Akhouri via cfe-commits]

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@@ -31,7 +31,7 @@ inline llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, LoanID ID) {
 struct AccessPath {
   const clang::ValueDecl *D;
 
-  AccessPath(const clang::ValueDecl *D) : D(D) {}
+  AccessPath(const clang::ValueDecl *D = nullptr) : D(D) {}
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kashika0112 wrote:

I have added a bool flag in Loan struct called `IsPlaceholderLoan` and we are not creating ExpireFacts for the loan if it is a placeholder loan in `handleLifetimeEnds`. The generated Facts look like this:

```
Function: foo
  Block B2:
    Issue (0 (Path: a) (Placeholder loan), ToOrigin: 0 (Decl: a))
  End of Block
  Block B1:
    Use (0 (Decl: a), Read)
    OriginFlow (Dest: 1 (Expr: ImplicitCastExpr), Src: 0 (Decl: a))
    OriginFlow (Dest: 2 (Expr: CXXConstructExpr), Src: 1 (Expr: ImplicitCastExpr))
    OriginEscapes (2 (Expr: CXXConstructExpr))
  End of Block
  Block B0:
  End of Block
  ```

https://github.com/llvm/llvm-project/pull/169767