[clang-tidy] Add check bugprone-misleading-setter-of-reference

clang-tools-extra/clang-tidy/bugprone/BugproneTidyModule.cpp

@@ -41,6 +41,7 @@
 #include "LambdaFunctionNameCheck.h"
 #include "MacroParenthesesCheck.h"
 #include "MacroRepeatedSideEffectsCheck.h"
+#include "MisleadingSetterOfReferenceCheck.h"
 #include "MisplacedOperatorInStrlenInAllocCheck.h"
 #include "MisplacedPointerArithmeticInAllocCheck.h"
 #include "MisplacedWideningCastCheck.h"
@@ -170,6 +171,8 @@ class BugproneModule : public ClangTidyModule {
         "bugprone-macro-parentheses");
     CheckFactories.registerCheck<MacroRepeatedSideEffectsCheck>(
         "bugprone-macro-repeated-side-effects");
+    CheckFactories.registerCheck<MisleadingSetterOfReferenceCheck>(
+        "bugprone-misleading-setter-of-reference");
     CheckFactories.registerCheck<MisplacedOperatorInStrlenInAllocCheck>(
         "bugprone-misplaced-operator-in-strlen-in-alloc");
     CheckFactories.registerCheck<MisplacedPointerArithmeticInAllocCheck>(

clang-tools-extra/clang-tidy/bugprone/CMakeLists.txt

@@ -42,6 +42,7 @@ add_clang_library(clangTidyBugproneModule STATIC
   LambdaFunctionNameCheck.cpp
   MacroParenthesesCheck.cpp
   MacroRepeatedSideEffectsCheck.cpp
+  MisleadingSetterOfReferenceCheck.cpp
   MisplacedOperatorInStrlenInAllocCheck.cpp
   MisplacedPointerArithmeticInAllocCheck.cpp
   MisplacedWideningCastCheck.cpp

clang-tools-extra/clang-tidy/bugprone/MisleadingSetterOfReferenceCheck.cpp

@@ -0,0 +1,61 @@
+//===--- 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(hasType(hasCanonicalType(referenceType(
+                                pointee(equalsBoundNode("type"))))))
+                      .bind("member");
+  auto AssignLHS = memberExpr(
+      hasObjectExpression(ignoringParenCasts(cxxThisExpr())), member(RefField));
+  auto DerefOperand = expr(ignoringParenCasts(
+      declRefExpr(to(parmVarDecl(equalsBoundNode("parm"))))));
+  auto AssignRHS = expr(ignoringParenCasts(
+      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(),
+          hasParameter(
+              0,
+              parmVarDecl(hasType(hasCanonicalType(pointerType(pointee(qualType(
+                              hasCanonicalType(qualType().bind("type"))))))))
+                  .bind("parm")),
+          hasBody(SetBody))
+          .bind("bad-set-function");
+  Finder->addMatcher(BadSetFunction, this);
+}
+
+void MisleadingSetterOfReferenceCheck::check(
+    const MatchFinder::MatchResult &Result) {
+  const auto *Found = Result.Nodes.getNodeAs<CXXMethodDecl>("bad-set-function");
+  const auto *Member = Result.Nodes.getNodeAs<FieldDecl>("member");
+
+  diag(Found->getBeginLoc(),
+       "function '%0' can be mistakenly used in order to change the "
+       "reference '%1' instead of the value of it; consider not using a "
+       "pointer as argument")
+      << Found->getName() << Member->getName();
+}
+
+} // namespace clang::tidy::bugprone

clang-tools-extra/clang-tidy/bugprone/MisleadingSetterOfReferenceCheck.h

@@ -0,0 +1,37 @@
+//===--- MisleadingSetterOfReferenceCheck.h - clang-tidy---------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_BUGPRONE_MISLEADINGSETTEROFREFERENCECHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_BUGPRONE_MISLEADINGSETTEROFREFERENCECHECK_H
+
+#include "../ClangTidyCheck.h"
+
+namespace clang::tidy::bugprone {
+
+/// Emits a warning when a setter-like function that has a pointer parameter
+/// is used to set value of a field with reference type.
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/bugprone/throw-keyword-missing.html
+class MisleadingSetterOfReferenceCheck : public ClangTidyCheck {
+public:
+  MisleadingSetterOfReferenceCheck(StringRef Name, ClangTidyContext *Context)
+      : ClangTidyCheck(Name, Context) {}
+  bool isLanguageVersionSupported(const LangOptions &LangOpts) const override {
+    return LangOpts.CPlusPlus;
+  }
+  void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+  void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+  std::optional<TraversalKind> getCheckTraversalKind() const override {
+    return TK_IgnoreUnlessSpelledInSource;
+  }
+};
+
+} // namespace clang::tidy::bugprone
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_BUGPRONE_MISLEADINGSETTEROFREFERENCECHECK_H

clang-tools-extra/docs/clang-tidy/checks/bugprone/misleading-setter-of-reference.rst

@@ -0,0 +1,47 @@
+.. title:: clang-tidy - bugprone-misleading-setter-of-reference
+
+bugprone-misleading-setter-of-reference
+=======================================
+
+Finds setter-like member functions that take a pointer parameter and set a
+(non-const) reference member of the same class with the pointed value.
+
+The checker detects public member functions that have a single parameter (which
+is a pointer) and contain a single (maybe overloaded) assignment operator call.
+The assignment should set a member variable with the dereference of the
+parameter pointer. The member variable can have any visibility.
+
+The fact that a setter function takes a pointer might cause the belief that an
+internal reference (if it would be a pointer) is changed instead of the
+pointed-to (or referenced) value.
+
+Example:
+
+.. code-block:: c++
+
+  class MyClass {
+    int &InternalRef;  // non-const reference member
+  public:
+    MyClass(int &Value) : InternalRef(Value) {}
+
+    // Warning: This setter could lead to unintended behaviour.
+    void setRef(int *Value) {
+      InternalRef = *Value;  // This assigns to the referenced value, not changing what ref_ references.
+    }
+  };
+
+  int main() {
+    int Value1 = 42;
+    int Value2 = 100;
+    MyClass X(Value1);
+
+    // This might look like it changes what InternalRef references to,
+    // but it actually modifies Value1 to be 100.
+    X.setRef(&Value2);
+  }
+
+Possible fixes:
+  - Change the parameter type of the "set" function to non-pointer or const reference
+    type.
+  - Change the type of the member variable to a pointer and in the "set"
+    function assign a value to the pointer (without dereference).

clang-tools-extra/test/clang-tidy/checkers/bugprone/misleading-setter-of-reference.cpp

@@ -0,0 +1,117 @@
+// RUN: %check_clang_tidy %s bugprone-misleading-setter-of-reference %t
+
+struct X {
+  X &operator=(const X &) { return *this; }
+private:
+  int &Mem;
+  friend class Test1;
+};
+
+class Test1 {
+  X &MemX;
+  int &MemI;
+protected:
+  long &MemL;
+public:
+  long &MemLPub;
+
+  Test1(X &MemX, int &MemI, long &MemL) : MemX(MemX), MemI(MemI), MemL(MemL), MemLPub(MemL) {}
+  void setI(int *NewValue) {
+    // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: function 'setI' can be mistakenly used in order to change the reference 'MemI' instead of the value of it
+    MemI = *NewValue;
+  }
+  void setL(long *NewValue) {
+    // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: function 'setL' can be mistakenly used in order to change the reference 'MemL' instead of the value of it
+    MemL = *NewValue;
+  }
+  void setX(X *NewValue) {
+    // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: function 'setX' can be mistakenly used in order to change the reference 'MemX' instead of the value of it
+    MemX = *NewValue;
+  }
+  void set1(int *NewValue) {
+    MemX.Mem = *NewValue;
+  }
+  void set2(int *NewValue) {
+    MemL = static_cast<long>(*NewValue);
+  }
+  void set3(int *NewValue) {
+    MemI = *NewValue;
+    MemL = static_cast<long>(*NewValue);
+  }
+  void set4(long *NewValue, int) {
+    MemL = *NewValue;
+  }
+  void setLPub(long *NewValue) {
+    // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: function 'setLPub' can be mistakenly used in order to change the reference 'MemLPub' instead of the value of it
+    MemLPub = *NewValue;
+  }
+
+protected:
+  void set5(long *NewValue) {
+    MemL = *NewValue;
+  }
+};
+
+class Base {
+protected:
+  int &MemI;
+};
+
+class Derived : public Base {
+public:
+  void setI(int *NewValue) {
+    // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: function 'setI' can be mistakenly used in order to change the reference 'MemI' instead of the value of it
+    MemI = *NewValue;
+  }
+};
+
+using UIntRef = unsigned int &;
+using UIntPtr = unsigned int *;
+using UInt = unsigned int;
+
+class AliasTest {
+  UIntRef Value1;
+  UInt &Value2;
+  unsigned int &Value3;
+public:
+  void setValue1(UIntPtr NewValue) {
+    // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: function 'setValue1' can be mistakenly used in order to change the reference 'Value1' instead of the value of it
+    Value1 = *NewValue;
+  }
+  void setValue2(unsigned int *NewValue) {
+    // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: function 'setValue2' can be mistakenly used in order to change the reference 'Value2' instead of the value of it
+    Value2 = *NewValue;
+  }
+  void setValue3(UInt *NewValue) {
+    // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: function 'setValue3' can be mistakenly used in order to change the reference 'Value3' instead of the value of it
+    Value3 = *NewValue;
+  }
+};
+
+template <typename T>
+class TemplateTest {
+  T &Mem;
+public:
+  TemplateTest(T &V) : Mem{V} {}
+  void setValue(T *NewValue) {
+    // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: function 'setValue' can be mistakenly used in order to change the reference 'Mem' instead of the value of it
+    Mem = *NewValue;
+  }
+};
+
+char CharValue;
+TemplateTest<char> TTChar{CharValue};
+
+template <typename T>
+class AddMember {
+protected:
+  T &Value;
+};
+
+class TemplateBaseTest : public AddMember<int> {
+public:
+  void setValue(int *NewValue) {
+    // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: function 'setValue' can be mistakenly used in order to change the reference 'Value' instead of the value of it
+    Value = *NewValue;
+  }
+};