[llvm-branch-commits] [clang] [LifetimeSafety] Associate origins to all l-valued expressions (PR #156896)

[Utkarsh Saxena via llvm-branch-commits]

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@@ -438,12 +452,31 @@ class FactGenerator : public ConstStmtVisitor<FactGenerator> {
   void VisitDeclStmt(const DeclStmt *DS) {
     for (const Decl *D : DS->decls())
       if (const auto *VD = dyn_cast<VarDecl>(D))
-        if (hasOrigin(VD->getType()))
+        if (hasOrigin(VD))
           if (const Expr *InitExpr = VD->getInit())
             addAssignOriginFact(*VD, *InitExpr);
   }
 
-  void VisitDeclRefExpr(const DeclRefExpr *DRE) { handleUse(DRE); }
+  void VisitDeclRefExpr(const DeclRefExpr *DRE) {
+    handleUse(DRE);
+    // For non-pointer/non-view types, a reference to the variable's storage
+    // is a borrow. We create a loan for it.
+    // For pointer/view types, we stick to the existing model for now and do
+    // not create an extra origin for the l-value expression itself.
+
+    // FIXME: A loan to `DeclRefExpr` for a pointer or view type can be
----------------
usx95 wrote:

I agree. An LValueToRValue would be responsible for propagating the correct (inner) origin when we have multiple origins for l-valued pointer-type expressions.

>  // FIXME: A loan to `DeclRefExpr` for a pointer or view type can be ambiguous 

Avoided mentioning the ambiguity here. Changed to 
```
TODO: A single origin for a `DeclRefExpr` for a pointer or view type 
is not sufficient to model the different levels of indirection.
```


https://github.com/llvm/llvm-project/pull/156896