[clang-tools-extra] [clang-tidy]Fix PreferMemberInitializer false positive for reassignment (PR #70316)

[Congcong Cai via cfe-commits]

================
@@ -570,3 +570,19 @@ struct PR52818  {
 
     int bar;
 };
+
+struct RefReassignment {
+  RefReassignment(int &i) : m_i{i} {
+    m_i = 1;
+  }
+  int & m_i;
+};
+
+struct ReassignmentAfterUnsafetyAssignment {
+  ReassignmentAfterUnsafetyAssignment() {
+    int a = 10;
+    m_i = a;
+    m_i = 1;
+  }
+  int m_i;
+};
----------------
HerrCai0907 wrote:

positive tests still have some issue. It will report for each assignments. But I don't find a good solution to handle this case. It's already marked in `isSafeAssignment`.
```c++
// TODO: Probably should guard against function calls that could have side
// effects or if they do reference another field that's initialized before this
// field, but is modified before the assignment.
```

https://github.com/llvm/llvm-project/pull/70316