[clang] [LifetimeSafety] Introduce buildOriginFlowChain for use-after-scope (PR #199345)

[Utkarsh Saxena via cfe-commits]

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@@ -70,6 +80,19 @@ class LifetimeSafetySemaHelperImpl : public LifetimeSafetySemaHelper {
       S.Diag(MovedExpr->getExprLoc(), diag::note_lifetime_safety_moved_here)
           << MovedExpr->getSourceRange();
     S.Diag(FreeLoc, diag::note_lifetime_safety_destroyed_here);
+
+    StringRef IssueStr;
+    for (const Expr *CurrExpr : reverse(OriginExprChain)) {
+      if (IssueStr.empty()) {
+        IssueStr = formatExpr(CurrExpr);
+        continue;
+      }
+
+      S.Diag(CurrExpr->getBeginLoc(),
+             diag::note_lifetime_safety_note_alias_chain)
+          << CurrExpr->getSourceRange() << formatExpr(CurrExpr) << IssueStr;
+    }
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usx95 wrote:

Let's do this in a separate method.

`void reportAliasingChain(llvm::ArrayRef<const Expr *> OriginExprChain);`


https://github.com/llvm/llvm-project/pull/199345