[clang-tools-extra] [NFC][clang-tidy]refactor isAssignmentToMemberOf in PreferMemberInitializerCheck (PR #71006)

[Piotr Zegar via cfe-commits]

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@@ -216,11 +216,12 @@ void PreferMemberInitializerCheck::check(
         return;
     }
 
-    const FieldDecl *Field = nullptr;
-    const Expr *InitValue = nullptr;
-    std::tie(Field, InitValue) = isAssignmentToMemberOf(Class, S, Ctor);
-    if (!Field)
+    std::optional<std::pair<const FieldDecl *, const Expr *>>
+        AssignmentToMember = isAssignmentToMemberOf(Class, S, Ctor);
+    if (!AssignmentToMember)
       continue;
+    const FieldDecl *Field = AssignmentToMember.value().first;
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PiotrZSL wrote:

you can use `->` operator here... No ned for value().

https://github.com/llvm/llvm-project/pull/71006