// RUN: %check_clang_tidy %s performance-move-const-arg %t namespace std { template struct remove_reference; template struct remove_reference { typedef _Tp type; }; template struct remove_reference<_Tp &> { typedef _Tp type; }; template struct remove_reference<_Tp &&> { typedef _Tp type; }; template constexpr typename std::remove_reference<_Tp>::type &&move(_Tp &&__t) { return static_cast::type &&>(__t); } template constexpr _Tp && forward(typename remove_reference<_Tp>::type &__t) noexcept { return static_cast<_Tp &&>(__t); } } // namespace std class A { public: A() {} A(const A &rhs) {} A(A &&rhs) {} }; using AlsoA = A; struct TriviallyCopyable { int i; }; using TrivialAlias = TriviallyCopyable; void f(TriviallyCopyable) {} void g() { TriviallyCopyable obj; f(std::move(obj)); // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: std::move of the variable 'obj' of the trivially-copyable type 'TriviallyCopyable' has no effect; remove std::move() [performance-move-const-arg] // CHECK-FIXES: f(obj); TrivialAlias obj2; f(std::move(obj2)); // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: std::move of the variable 'obj2' of the trivially-copyable type 'TrivialAlias' (aka 'TriviallyCopyable') has no effect; remove std::move() [performance-move-const-arg] // CHECK-FIXES: f(obj2); } int f1() { return std::move(42); // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: std::move of the expression of the trivially-copyable type 'int' has no effect; remove std::move() [performance-move-const-arg] // CHECK-FIXES: return 42; } int f2(int x2) { return std::move(x2); // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: std::move of the variable 'x2' of the trivially-copyable type 'int' // CHECK-FIXES: return x2; } int *f3(int *x3) { return std::move(x3); // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: std::move of the variable 'x3' of the trivially-copyable type 'int *' // CHECK-FIXES: return x3; } A f4(A x4) { return std::move(x4); } AlsoA f4_a(AlsoA x4) { return std::move(x4); } A f5(const A x5) { return std::move(x5); // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: std::move of the const variable 'x5' has no effect; remove std::move() or make the variable non-const [performance-move-const-arg] // CHECK-FIXES: return x5; } AlsoA f5_a(const AlsoA x5) { return std::move(x5); // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: std::move of the const variable 'x5' has no effect; remove std::move() or make the variable non-const [performance-move-const-arg] // CHECK-FIXES: return x5; } template T f6(const T x6) { return std::move(x6); } void f7() { int a = f6(10); } #define M1(x) x void f8() { const A a; M1(A b = std::move(a);) // CHECK-MESSAGES: :[[@LINE-1]]:12: warning: std::move of the const variable 'a' has no effect; remove std::move() or make the variable non-const // CHECK-FIXES: M1(A b = a;) } #define M2(x) std::move(x) int f9() { return M2(1); } template T f10(const int x10) { return std::move(x10); // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: std::move of the const variable 'x10' of the trivially-copyable type 'const int' has no effect; remove std::move() [performance-move-const-arg] // CHECK-FIXES: return x10; } void f11() { f10(1); f10(1); } class NoMoveSemantics { public: NoMoveSemantics(); NoMoveSemantics(const NoMoveSemantics &); NoMoveSemantics &operator=(const NoMoveSemantics &); }; using NoMoveSemanticsAlias = NoMoveSemantics; void callByConstRef(const NoMoveSemantics &); void callByConstRef(int i, const NoMoveSemantics &); void moveToConstReferencePositives() { NoMoveSemantics obj; // Basic case. callByConstRef(std::move(obj)); // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: passing result of std::move() as // CHECK-FIXES: callByConstRef(obj); // Also works for second argument. callByConstRef(1, std::move(obj)); // CHECK-MESSAGES: :[[@LINE-1]]:21: warning: passing result of std::move() as // CHECK-FIXES: callByConstRef(1, obj); // Works if std::move() applied to a temporary. callByConstRef(std::move(NoMoveSemantics())); // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: passing result of std::move() as // CHECK-FIXES: callByConstRef(NoMoveSemantics()); // Works if calling a copy constructor. NoMoveSemantics other(std::move(obj)); // CHECK-MESSAGES: :[[@LINE-1]]:25: warning: passing result of std::move() as // CHECK-FIXES: NoMoveSemantics other(obj); // Works if calling assignment operator. other = std::move(obj); // CHECK-MESSAGES: :[[@LINE-1]]:11: warning: passing result of std::move() as // CHECK-FIXES: other = obj; } void moveToConstReferencePositivesAlias() { NoMoveSemanticsAlias obj; // Basic case. callByConstRef(std::move(obj)); // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: passing result of std::move() as a const reference argument; no move will actually happen [performance-move-const-arg] // CHECK-FIXES: callByConstRef(obj); // Also works for second argument. callByConstRef(1, std::move(obj)); // CHECK-MESSAGES: :[[@LINE-1]]:21: warning: passing result of std::move() as a const reference argument; no move will actually happen [performance-move-const-arg] // CHECK-FIXES: callByConstRef(1, obj); // Works if std::move() applied to a temporary. callByConstRef(std::move(NoMoveSemanticsAlias())); // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: passing result of std::move() as a const reference argument; no move will actually happen [performance-move-const-arg] // CHECK-FIXES: callByConstRef(NoMoveSemanticsAlias()); // Works if calling a copy constructor. NoMoveSemanticsAlias other(std::move(obj)); // CHECK-MESSAGES: :[[@LINE-1]]:30: warning: passing result of std::move() as a const reference argument; no move will actually happen [performance-move-const-arg] // CHECK-FIXES: NoMoveSemanticsAlias other(obj); // Works if calling assignment operator. other = std::move(obj); // CHECK-MESSAGES: :[[@LINE-1]]:11: warning: passing result of std::move() as a const reference argument; no move will actually happen [performance-move-const-arg] // CHECK-FIXES: other = obj; } class MoveSemantics { public: MoveSemantics(); MoveSemantics(MoveSemantics &&); MoveSemantics &operator=(MoveSemantics &&); }; using MoveSemanticsAlias = MoveSemantics; void callByValue(MoveSemantics); void callByRValueRef(MoveSemantics &&); template void templateFunction(T obj) { T other = std::move(obj); } #define M3(T, obj) \ do { \ T other = std::move(obj); \ } while (true) #define CALL(func) (func)() void moveToConstReferenceNegatives() { // No warning when actual move takes place. MoveSemantics move_semantics; callByValue(std::move(move_semantics)); callByRValueRef(std::move(move_semantics)); MoveSemantics other(std::move(move_semantics)); other = std::move(move_semantics); // No warning if std::move() not used. NoMoveSemantics no_move_semantics; callByConstRef(no_move_semantics); // No warning if instantiating a template. templateFunction(no_move_semantics); // No warning inside of macro expansions. M3(NoMoveSemantics, no_move_semantics); // No warning inside of macro expansion, even if the macro expansion is inside // a lambda that is, in turn, an argument to a macro. CALL([no_move_semantics] { M3(NoMoveSemantics, no_move_semantics); }); auto lambda = [] {}; auto lambda2 = std::move(lambda); } void moveToConstReferenceNegativesAlias() { // No warning when actual move takes place. MoveSemanticsAlias move_semantics; callByValue(std::move(move_semantics)); callByRValueRef(std::move(move_semantics)); MoveSemanticsAlias other(std::move(move_semantics)); other = std::move(move_semantics); // No warning if std::move() not used. NoMoveSemanticsAlias no_move_semantics; callByConstRef(no_move_semantics); // No warning if instantiating a template. templateFunction(no_move_semantics); // No warning inside of macro expansions. M3(NoMoveSemanticsAlias, no_move_semantics); // No warning inside of macro expansion, even if the macro expansion is inside // a lambda that is, in turn, an argument to a macro. CALL([no_move_semantics] { M3(NoMoveSemanticsAlias, no_move_semantics); }); auto lambda = [] {}; auto lambda2 = std::move(lambda); } class MoveOnly { public: MoveOnly(const MoveOnly &other) = delete; MoveOnly &operator=(const MoveOnly &other) = delete; MoveOnly(MoveOnly &&other) = default; MoveOnly &operator=(MoveOnly &&other) = default; }; template void Q(T); void moveOnlyNegatives(MoveOnly val) { Q(std::move(val)); } using MoveOnlyAlias = MoveOnly; void fmovable(MoveSemantics); void lambda1() { auto f = [](MoveSemantics m) { fmovable(std::move(m)); }; f(MoveSemantics()); } template struct function {}; template class function { public: function() = default; void operator()(Args... args) const { fmovable(std::forward(args)...); } }; void functionInvocation() { function callback; MoveSemantics m; callback(std::move(m)); } void functionInvocationAlias() { function callback; MoveSemanticsAlias m; callback(std::move(m)); } void lambda2() { function callback; auto f = [callback = std::move(callback)](MoveSemantics m) mutable { // CHECK-MESSAGES: :[[@LINE-1]]:24: warning: std::move of the variable 'callback' of the trivially-copyable type 'function' has no effect; remove std::move() // CHECK-FIXES: auto f = [callback = callback](MoveSemantics m) mutable { callback(std::move(m)); }; f(MoveSemantics()); } void lambda2Alias() { function callback; auto f = [callback = std::move(callback)](MoveSemanticsAlias m) mutable { // CHECK-MESSAGES: :[[@LINE-1]]:24: warning: std::move of the variable 'callback' of the trivially-copyable type 'function' (aka 'function') has no effect; remove std::move() [performance-move-const-arg] // CHECK-FIXES: auto f = [callback = callback](MoveSemanticsAlias m) mutable { callback(std::move(m)); }; f(MoveSemanticsAlias()); } void showInt(int &&v); void showInt(int v1, int &&v2); void showPointer(const char *&&s); void showPointer2(const char *const &&s); void showTriviallyCopyable(TriviallyCopyable &&obj); void showTriviallyCopyablePointer(const TriviallyCopyable *&&obj); void testFunctions() { int a = 10; showInt(std::move(a)); // CHECK-MESSAGES: :[[@LINE-1]]:11: warning: std::move of the variable 'a' of the trivially-copyable type 'int' has no effect [performance-move-const-arg] // CHECK-MESSAGES: :[[@LINE-10]]:20: note: consider changing the 1st parameter of 'showInt' from 'int &&' to 'const int &' showInt(int()); showInt(a, std::move(a)); // CHECK-MESSAGES: :[[@LINE-1]]:14: warning: std::move of the variable 'a' of the trivially-copyable type 'int' has no effect [performance-move-const-arg] // CHECK-MESSAGES: :[[@LINE-13]]:28: note: consider changing the 2nd parameter of 'showInt' from 'int &&' to 'const int &' const char* s = ""; showPointer(std::move(s)); // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: std::move of the variable 's' of the trivially-copyable type 'const char *' has no effect [performance-move-const-arg] // CHECK-MESSAGES: :[[@LINE-16]]:32: note: consider changing the 1st parameter of 'showPointer' from 'const char *&&' to 'const char *' showPointer2(std::move(s)); // CHECK-MESSAGES: :[[@LINE-1]]:16: warning: std::move of the variable 's' of the trivially-copyable type 'const char *' has no effect [performance-move-const-arg] // CHECK-MESSAGES: :[[@LINE-18]]:39: note: consider changing the 1st parameter of 'showPointer2' from 'const char *const &&' to 'const char *const' TriviallyCopyable *obj = new TriviallyCopyable(); showTriviallyCopyable(std::move(*obj)); // CHECK-MESSAGES: :[[@LINE-1]]:25: warning: std::move of the expression of the trivially-copyable type 'TriviallyCopyable' has no effect [performance-move-const-arg] // CHECK-MESSAGES: :[[@LINE-21]]:48: note: consider changing the 1st parameter of 'showTriviallyCopyable' from 'TriviallyCopyable &&' to 'const TriviallyCopyable &' showTriviallyCopyablePointer(std::move(obj)); // CHECK-MESSAGES: :[[@LINE-1]]:32: warning: std::move of the variable 'obj' of the trivially-copyable type 'TriviallyCopyable *' has no effect [performance-move-const-arg] // CHECK-MESSAGES: :[[@LINE-23]]:62: note: consider changing the 1st parameter of 'showTriviallyCopyablePointer' from 'const TriviallyCopyable *&&' to 'const TriviallyCopyable *' TrivialAlias* obj2 = new TrivialAlias(); showTriviallyCopyable(std::move(*obj)); // CHECK-MESSAGES: :[[@LINE-1]]:25: warning: std::move of the expression of the trivially-copyable type 'TriviallyCopyable' has no effect [performance-move-const-arg] // CHECK-MESSAGES: :[[@LINE-28]]:48: note: consider changing the 1st parameter of 'showTriviallyCopyable' from 'TriviallyCopyable &&' to 'const TriviallyCopyable &' showTriviallyCopyablePointer(std::move(obj)); // CHECK-MESSAGES: :[[@LINE-1]]:32: warning: std::move of the variable 'obj' of the trivially-copyable type 'TriviallyCopyable *' has no effect [performance-move-const-arg] // CHECK-MESSAGES: :[[@LINE-30]]:62: note: consider changing the 1st parameter of 'showTriviallyCopyablePointer' from 'const TriviallyCopyable *&&' to 'const TriviallyCopyable *' } template void forwardToShowInt(T && t) { showInt(static_cast(t)); } void testTemplate() { int a = 10; forwardToShowInt(std::move(a)); // CHECK-MESSAGES: :[[@LINE-1]]:20: warning: std::move of the variable 'a' of the trivially-copyable type 'int' has no effect [performance-move-const-arg] } struct Tmp { Tmp(); Tmp(int &&a); Tmp(int v1, int &&a); Tmp(const char *&&s); Tmp(TriviallyCopyable&& obj); Tmp(const TriviallyCopyable *&&obj); void showTmp(TriviallyCopyable&& t); static void showTmpStatic(TriviallyCopyable&& t); }; using TmpAlias = Tmp; void testMethods() { Tmp t; int a = 10; Tmp t1(std::move(a)); // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: std::move of the variable 'a' of the trivially-copyable type 'int' has no effect [performance-move-const-arg] // CHECK-MESSAGES: :[[@LINE-15]]:13: note: consider changing the 1st parameter of 'Tmp' from 'int &&' to 'const int &' Tmp t2(a, std::move(a)); // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: std::move of the variable 'a' of the trivially-copyable type 'int' has no effect [performance-move-const-arg] // CHECK-MESSAGES: :[[@LINE-17]]:21: note: consider changing the 2nd parameter of 'Tmp' from 'int &&' to 'const int &' const char* s = ""; Tmp t3(std::move(s)); // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: std::move of the variable 's' of the trivially-copyable type 'const char *' has no effect [performance-move-const-arg] // CHECK-MESSAGES: :[[@LINE-20]]:21: note: consider changing the 1st parameter of 'Tmp' from 'const char *&&' to 'const char *' TriviallyCopyable *obj = new TriviallyCopyable(); Tmp t4(std::move(*obj)); // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: std::move of the expression of the trivially-copyable type 'TriviallyCopyable' has no effect [performance-move-const-arg] // CHECK-MESSAGES: :[[@LINE-23]]:27: note: consider changing the 1st parameter of 'Tmp' from 'TriviallyCopyable &&' to 'const TriviallyCopyable &' Tmp t5(std::move(obj)); // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: std::move of the variable 'obj' of the trivially-copyable type 'TriviallyCopyable *' has no effect [performance-move-const-arg] // CHECK-MESSAGES: :[[@LINE-25]]:34: note: consider changing the 1st parameter of 'Tmp' from 'const TriviallyCopyable *&&' to 'const TriviallyCopyable *' t.showTmp(std::move(*obj)); // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: std::move of the expression of the trivially-copyable type 'TriviallyCopyable' has no effect [performance-move-const-arg] // CHECK-MESSAGES: :[[@LINE-27]]:36: note: consider changing the 1st parameter of 'showTmp' from 'TriviallyCopyable &&' to 'const TriviallyCopyable &' Tmp::showTmpStatic(std::move(*obj)); // CHECK-MESSAGES: :[[@LINE-1]]:22: warning: std::move of the expression of the trivially-copyable type 'TriviallyCopyable' has no effect [performance-move-const-arg] // CHECK-MESSAGES: :[[@LINE-29]]:49: note: consider changing the 1st parameter of 'showTmpStatic' from 'TriviallyCopyable &&' to 'const TriviallyCopyable &' } void testMethodsAlias() { TmpAlias t; int a = 10; TmpAlias t1(std::move(a)); // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: std::move of the variable 'a' of the trivially-copyable type 'int' has no effect [performance-move-const-arg] // CHECK-MESSAGES: :[[@LINE-43]]:13: note: consider changing the 1st parameter of 'Tmp' from 'int &&' to 'const int &' TmpAlias t2(a, std::move(a)); // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: std::move of the variable 'a' of the trivially-copyable type 'int' has no effect [performance-move-const-arg] // CHECK-MESSAGES: :[[@LINE-45]]:21: note: consider changing the 2nd parameter of 'Tmp' from 'int &&' to 'const int &' const char* s = ""; TmpAlias t3(std::move(s)); // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: std::move of the variable 's' of the trivially-copyable type 'const char *' has no effect [performance-move-const-arg] // CHECK-MESSAGES: :[[@LINE-48]]:21: note: consider changing the 1st parameter of 'Tmp' from 'const char *&&' to 'const char *' TrivialAlias *obj = new TrivialAlias(); TmpAlias t4(std::move(*obj)); // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: std::move of the expression of the trivially-copyable type 'TrivialAlias' (aka 'TriviallyCopyable') has no effect [performance-move-const-arg] // CHECK-MESSAGES: :[[@LINE-51]]:27: note: consider changing the 1st parameter of 'Tmp' from 'TriviallyCopyable &&' to 'const TriviallyCopyable &' TmpAlias t5(std::move(obj)); // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: std::move of the variable 'obj' of the trivially-copyable type 'TrivialAlias *' (aka 'TriviallyCopyable *') has no effect [performance-move-const-arg] // CHECK-MESSAGES: :[[@LINE-53]]:34: note: consider changing the 1st parameter of 'Tmp' from 'const TriviallyCopyable *&&' to 'const TriviallyCopyable *' t.showTmp(std::move(*obj)); // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: std::move of the expression of the trivially-copyable type 'TrivialAlias' (aka 'TriviallyCopyable') has no effect [performance-move-const-arg] // CHECK-MESSAGES: :[[@LINE-55]]:36: note: consider changing the 1st parameter of 'showTmp' from 'TriviallyCopyable &&' to 'const TriviallyCopyable &' TmpAlias::showTmpStatic(std::move(*obj)); // CHECK-MESSAGES: :[[@LINE-1]]:27: warning: std::move of the expression of the trivially-copyable type 'TrivialAlias' (aka 'TriviallyCopyable') has no effect [performance-move-const-arg] // CHECK-MESSAGES: :[[@LINE-57]]:49: note: consider changing the 1st parameter of 'showTmpStatic' from 'TriviallyCopyable &&' to 'const TriviallyCopyable &' } void showA(A &&v) {} void testA() { A a; showA(std::move(a)); } void testAAlias() { AlsoA a; showA(std::move(a)); } void testFuncPointer() { int a = 10; void (*choice)(int, int &&); choice = showInt; choice(std::move(a), std::move(a)); // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: std::move of the variable 'a' of the trivially-copyable type 'int' has no effect; remove std::move() [performance-move-const-arg] // CHECK-FIXES: choice(a, std::move(a)); // CHECK-MESSAGES: :[[@LINE-3]]:24: warning: std::move of the variable 'a' of the trivially-copyable type 'int' has no effect [performance-move-const-arg] } namespace issue_62550 { struct NonMoveConstructable { NonMoveConstructable(); NonMoveConstructable(const NonMoveConstructable&); NonMoveConstructable& operator=(const NonMoveConstructable&); NonMoveConstructable& operator=(NonMoveConstructable&&); }; void testNonMoveConstructible() { NonMoveConstructable t1; NonMoveConstructable t2{std::move(t1)}; // CHECK-MESSAGES: :[[@LINE-1]]:27: warning: passing result of std::move() as a const reference argument; no move will actually happen [performance-move-const-arg] // CHECK-MESSAGES: :[[@LINE-11]]:8: note: 'NonMoveConstructable' is not move constructible } struct NonMoveAssignable { NonMoveAssignable(); NonMoveAssignable(const NonMoveAssignable&); NonMoveAssignable(NonMoveAssignable&&); NonMoveAssignable& operator=(const NonMoveAssignable&); }; void testNonMoveAssignable() { NonMoveAssignable t1; NonMoveAssignable t2; t2 = std::move(t1); // CHECK-MESSAGES: :[[@LINE-1]]:8: warning: passing result of std::move() as a const reference argument; no move will actually happen [performance-move-const-arg] // CHECK-MESSAGES: :[[@LINE-14]]:8: note: 'NonMoveAssignable' is not move assignable } struct NonMoveable { NonMoveable(); NonMoveable(const NonMoveable&); NonMoveable& operator=(const NonMoveable&); }; void testNonMoveable() { NonMoveable t1; NonMoveable t2{std::move(t1)}; // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: passing result of std::move() as a const reference argument; no move will actually happen [performance-move-const-arg] // CHECK-MESSAGES: :[[@LINE-10]]:8: note: 'NonMoveable' is not move assignable/constructible t1 = std::move(t2); // CHECK-MESSAGES: :[[@LINE-1]]:8: warning: passing result of std::move() as a const reference argument; no move will actually happen [performance-move-const-arg] // CHECK-MESSAGES: :[[@LINE-14]]:8: note: 'NonMoveable' is not move assignable/constructible } using AlsoNonMoveable = NonMoveable; void testAlsoNonMoveable() { AlsoNonMoveable t1; AlsoNonMoveable t2{std::move(t1)}; // CHECK-MESSAGES: :[[@LINE-1]]:22: warning: passing result of std::move() as a const reference argument; no move will actually happen [performance-move-const-arg] // CHECK-MESSAGES: :[[@LINE-23]]:8: note: 'NonMoveable' is not move assignable/constructible t1 = std::move(t2); // CHECK-MESSAGES: :[[@LINE-1]]:8: warning: passing result of std::move() as a const reference argument; no move will actually happen [performance-move-const-arg] // CHECK-MESSAGES: :[[@LINE-27]]:8: note: 'NonMoveable' is not move assignable/constructible } } // namespace issue_62550