[clang] [Clang] eliminate shadowing warnings for parameters using deducing this (PR #114813)

[Oleksandr T. via cfe-commits]

================
@@ -8236,11 +8236,14 @@ void Sema::CheckShadow(NamedDecl *D, NamedDecl *ShadowedDecl,
   DeclContext *NewDC = D->getDeclContext();
 
   if (FieldDecl *FD = dyn_cast<FieldDecl>(ShadowedDecl)) {
-    // Fields are not shadowed by variables in C++ static methods.
-    if (CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(NewDC))
+    if (CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(NewDC)) {
+      // Fields are not shadowed by variables in C++ static methods.
       if (MD->isStatic())
         return;
 
+      if (!MD->getParent()->isLambda() && MD->isExplicitObjectMemberFunction())
+        return;
----------------
a-tarasyuk wrote:

@Sirraide Thanks for the feedback. I've added an additional test. 

> Maybe this also warrants a comment, because at first it wasn’t immediately obvious to me why we’d want to ignore lambda call operators here.

Thanks for bringing that to my attention. In such cases

```cpp
struct C {
  int b = 5;
  int foo() {
    return [a = b]() {
      return [=, b = a]() {
        return b;
      }();
    }();
  }
};
```

depending exclusively on `isExplicitObjectMemberFunction` isn’t safe, as it could lead to assertion failures during type resolution

https://github.com/llvm/llvm-project/blob/1a590870b6b3452934ecc245e01957fdab48909c/clang/lib/AST/Decl.cpp#L3699-L3702

There’s an option to restrict the null type or to validate the parent scope. I've been trying to find a suitable utility to do this, but I haven’t had any luck. If there’s one available, I’d appreciate it if you could point me to it. thanks










https://github.com/llvm/llvm-project/pull/114813