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

[Yuan Suo via cfe-commits]

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@@ -471,13 +474,47 @@ class LifetimeSafetySemaHelperImpl : public LifetimeSafetySemaHelper {
   }
 
   std::string getDiagSubjectDescription(const Expr *E) {
+    E = E->IgnoreImpCasts();
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suoyuan666 wrote:

The main purpose here is to filter out `ImplicitCastExpr`, as the Origin is often bound to it. I believe `IgnoreImpCasts()` should be sufficient.

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