[clang] [LifetimeSafety] Prevent false-negative lifetimebound verification when origin escapes in an unrelated manner (PR #200786)

[Gábor Horváth via cfe-commits]

================
@@ -148,9 +148,10 @@ class LifetimeChecker {
       // field!
     };
     auto CheckImplicitThis = [&](const CXXMethodDecl *MD) {
-      if (implicitObjectParamIsLifetimeBound(MD))
-        VerifiedLiftimeboundEscapes.insert(MD);
-      else if (auto *ReturnEsc = dyn_cast<ReturnEscapeFact>(OEF))
+      if (implicitObjectParamIsLifetimeBound(MD)) {
+        if (isa<ReturnEscapeFact>(OEF))
+          VerifiedLiftimeboundEscapes.insert(MD);
+      } else if (auto *ReturnEsc = dyn_cast<ReturnEscapeFact>(OEF))
         AnnotationWarningsMap.try_emplace(MD, ReturnEsc->getReturnExpr());
----------------
Xazax-hun wrote:

I think it might be possible to simplify this a bit. 

```suggestion
      if (auto *ReturnEsc = dyn_cast<ReturnEscapeFact>(OEF)) {
        if (implicitObjectParamIsLifetimeBound(MD))
          VerifiedLiftimeboundEscapes.insert(MD);
        else
          AnnotationWarningsMap.try_emplace(MD, ReturnEsc->getReturnExpr());
      } 
```

https://github.com/llvm/llvm-project/pull/200786