[clang-tools-extra] [clang-tidy] Fix false positives with deducing this in `readability-convert-member-functions-to-static` check (PR #141391)

[Baranov Victor via cfe-commits]

================
@@ -62,6 +62,16 @@ AST_MATCHER(CXXMethodDecl, usesThis) {
       return false; // Stop traversal.
     }
 
+    bool VisitDeclRefExpr(const DeclRefExpr *E) {
+      if (const auto *PVD = dyn_cast_if_present<ParmVarDecl>(E->getDecl());
+          PVD && PVD->isExplicitObjectParameter()) {
+        Used = true;
+        return false; // Stop traversal.
+      }
+
+      return true;
+    }
----------------
vbvictor wrote:

I think we should not introduce a new method in `RecursiveASTVisitor`.
As for now, you would traverse every `DeclRefExpr` in function body trying to `dyn_cast` which is not efficient.
Instead, We should only check for `this` in methods parameters, so you can write 
```cpp
Finder->addMatcher(
      cxxMethodDecl(
          isDefinition(), isUserProvided(),
          unless(anyOf(
              hasAnyParameter(isExplicitObjectParameter())    
```

https://github.com/llvm/llvm-project/pull/141391