[clang] [LifetimeSafety] Implement multi-level origins (PR #168344)

[Gábor Horváth via cfe-commits]

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@@ -210,11 +317,24 @@ void FactsGenerator::VisitInitListExpr(const InitListExpr *ILE) {
 
 void FactsGenerator::VisitMaterializeTemporaryExpr(
     const MaterializeTemporaryExpr *MTE) {
-  if (!hasOrigin(MTE))
+  OriginTree *MTETree = getTree(*MTE);
+  OriginTree *SubExprTree = getTree(*MTE->getSubExpr());
+  if (!MTETree)
     return;
-  // A temporary object's origin is the same as the origin of the
-  // expression that initializes it.
-  killAndFlowOrigin(*MTE, *MTE->getSubExpr());
+  if (MTE->isGLValue()) {
+    assert(!SubExprTree ||
+           MTETree->getDepth() == SubExprTree->getDepth() + 1 && "todo doc.");
+    // Issue a loan to the MTE.
+    // const Loan *L = createLoan(FactMgr, MTE);
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Xazax-hun wrote:

Nit: commented out code. 

https://github.com/llvm/llvm-project/pull/168344