[clang] [alpha.webkit.RetainPtrCtorAdoptChecker] Don't treat assignment to an +1 out argument as a leak (PR #161633)

[Balázs Benics via cfe-commits]

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@@ -355,14 +355,30 @@ class RetainPtrCtorAdoptChecker
   void visitBinaryOperator(const BinaryOperator *BO) const {
     if (!BO->isAssignmentOp())
       return;
-    if (!isa<ObjCIvarRefExpr>(BO->getLHS()))
-      return;
+    auto *LHS = BO->getLHS();
     auto *RHS = BO->getRHS()->IgnoreParenCasts();
-    const Expr *Inner = nullptr;
-    if (isAllocInit(RHS, &Inner)) {
-      CreateOrCopyFnCall.insert(RHS);
-      if (Inner)
-        CreateOrCopyFnCall.insert(Inner);
+    if (isa<ObjCIvarRefExpr>(LHS)) {
+      const Expr *Inner = nullptr;
+      if (isAllocInit(RHS, &Inner)) {
+        CreateOrCopyFnCall.insert(RHS);
+        if (Inner)
+          CreateOrCopyFnCall.insert(Inner);
+      }
+      return;
+    } else if (auto *UO = dyn_cast<UnaryOperator>(LHS)) {
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steakhal wrote:

In LLVM I think we try to obey the rule of no [else-after-return](https://clang.llvm.org/extra/clang-tidy/checks/readability/else-after-return.html) rule.
Honouring the rule usually means that we can reduce indentation of the guarded block by one level.

https://github.com/llvm/llvm-project/pull/161633