[clang-tools-extra] [clang-tidy] Add check bugprone-misleading-setter-of-reference (PR #132242)

[Donát Nagy via cfe-commits]

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@@ -0,0 +1,58 @@
+//===--- MisleadingSetterOfReferenceCheck.cpp - clang-tidy-----------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "MisleadingSetterOfReferenceCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::bugprone {
+
+void MisleadingSetterOfReferenceCheck::registerMatchers(MatchFinder *Finder) {
+  auto RefField =
+      fieldDecl(unless(isPublic()),
+                hasType(referenceType(pointee(equalsBoundNode("type")))))
+          .bind("member");
+  auto AssignLHS =
+      memberExpr(hasObjectExpression(cxxThisExpr()), member(RefField));
+  auto DerefOperand = expr(ignoringParenImpCasts(
+      declRefExpr(to(parmVarDecl(equalsBoundNode("parm"))))));
+  auto AssignRHS = expr(ignoringParenImpCasts(
+      unaryOperator(hasOperatorName("*"), hasUnaryOperand(DerefOperand))));
+
+  auto BinaryOpAssign = binaryOperator(hasOperatorName("="), hasLHS(AssignLHS),
+                                       hasRHS(AssignRHS));
+  auto CXXOperatorCallAssign = cxxOperatorCallExpr(
+      hasOverloadedOperatorName("="), hasLHS(AssignLHS), hasRHS(AssignRHS));
+
+  auto SetBody =
+      compoundStmt(statementCountIs(1),
+                   anyOf(has(BinaryOpAssign), has(CXXOperatorCallAssign)));
+  auto BadSetFunction =
+      cxxMethodDecl(parameterCountIs(1), isPublic(),
----------------
NagyDonat wrote:

I think exposing a protected setter method (which has this particular bug) as a public method of a derived class would be very rare, but I'm not opposed to adding `isProtected()` if you think that it would be more elegant.

I can also accept removing visibility constraints on the method -- private setter methods should be vanishingly rare, so excluding them complicates the check with very limited practical benefits.

https://github.com/llvm/llvm-project/pull/132242