173 lines · cpp
1// RUN: %clang_analyze_cc1 -analyzer-checker=core,alpha.core\2// RUN: -analyzer-checker=debug.ExprInspection\3// RUN: -Wno-dangling -Wno-c++1z-extensions\4// RUN: -verify=expected,cpp14\5// RUN: -x c++ -std=c++14 %s6// RUN: %clang_analyze_cc1 -analyzer-checker=core,alpha.core\7// RUN: -analyzer-checker=debug.ExprInspection\8// RUN: -analyzer-config elide-constructors=false\9// RUN: -Wno-dangling -Wno-c++1z-extensions\10// RUN: -verify=expected,cpp14\11// RUN: -x c++ -std=c++14 %s12// RUN: %clang_analyze_cc1 -analyzer-checker=core,alpha.core\13// RUN: -analyzer-checker=debug.ExprInspection\14// RUN: -Wno-dangling -verify=expected,cpp17\15// RUN: -x c++ -std=c++17 %s16 17template<typename T>18void clang_analyzer_dump(T&&) {}19 20template<typename T>21T create() { return T{}; }22 23template<typename T>24T const& select(bool cond, T const& t, T const& u) { return cond ? t : u; }25 26struct Composite {27 int x;28 int y;29};30 31struct Derived : Composite {32 int z;33};34 35template<typename T>36struct Array {37 T array[20];38 39 T&& front() && { return static_cast<T&&>(array[0]); }40};41 42void whole_object() {43 int const& i = 10; // extends `int`44 clang_analyzer_dump(i); // expected-warning-re {{&lifetime_extended_object{int, i, S{{[0-9]+}}} }}45 Composite&& c = Composite{}; // extends `Composite`46 clang_analyzer_dump(c); // expected-warning-re {{&lifetime_extended_object{Composite, c, S{{[0-9]+}}} }}47 auto&& a = Array<int>{}; // extends `Array<int>`48 clang_analyzer_dump(a); // expected-warning-re {{&lifetime_extended_object{Array<int>, a, S{{[0-9]+}}} }}49 Composite&& d = Derived{}; // extends `Derived`50 clang_analyzer_dump(d); // expected-warning-re {{&Base{lifetime_extended_object{Derived, d, S{{[0-9]+}}},Composite} }}51}52 53void member_access() {54 int&& x = Composite{}.x; // extends `Composite`55 clang_analyzer_dump(x); // expected-warning-re {{&lifetime_extended_object{Composite, x, S{{[0-9]+}}}.x }}56 int&& y = create<Composite>().y; // extends `Composite`57 clang_analyzer_dump(y); // expected-warning-re {{&lifetime_extended_object{struct Composite, y, S{{[0-9]+}}}.y }}58 int&& d = Array<int>{}.front(); // dangles `Array<int>`59 clang_analyzer_dump(d); // expected-warning-re {{&Element{temp_object{Array<int>, S{{[0-9]+}}}.array,0 S64b,int} }}60}61 62void array_subscript() {63 int&& i = Array<int>{}.array[0]; // extends `Array<int>`64 clang_analyzer_dump(i); // expected-warning-re {{&Element{lifetime_extended_object{Array<int>, i, S{{[0-9]+}}}.array,0 S64b,int} }}65 auto&& c = Array<Composite>{}.array[0]; // extends `Array<int>`66 clang_analyzer_dump(c); // expected-warning-re {{&Element{lifetime_extended_object{Array<Composite>, c, S{{[0-9]+}}}.array,0 S64b,struct Composite} }}67 auto&& x = Array<Composite>{}.array[0].x; // extends `Array<Composite>`68 clang_analyzer_dump(x); // expected-warning-re {{&Element{lifetime_extended_object{Array<Composite>, x, S{{[0-9]+}}}.array,0 S64b,struct Composite}.x }}69}70 71void ternary(bool cond) {72 Composite cc;73 // Value category mismatch of the operands (lvalue and xvalue), ternary produces prvalue74 auto&& ternaryProducesPRvalue = cond ? Composite{}.x : cc.x; // extends prvalue of 'int', `Composite` in true branch is destroyed75 clang_analyzer_dump(ternaryProducesPRvalue); // expected-warning-re {{&lifetime_extended_object{int, ternaryProducesPRvalue, S{{[0-9]+}}} }}76 77 // Value category agrees (xvalues), lifetime extension is triggered78 auto&& branchesExtended = cond ? Composite{}.x : static_cast<Composite&&>(cc).x; // extends `Composite` in true branch79 clang_analyzer_dump(branchesExtended);80 // expected-warning-re@-1 {{&lifetime_extended_object{Composite, branchesExtended, S{{[0-9]+}}}.x }}81 // expected-warning@-2 {{&cc.x }}82 83 // Object of different types in branches are lifetime extended84 auto&& extendingDifferentTypes = cond ? Composite{}.x : Array<int>{}.array[0]; // extends `Composite` or `Array<int>`85 clang_analyzer_dump(extendingDifferentTypes);86 // expected-warning-re@-1 {{&lifetime_extended_object{Composite, extendingDifferentTypes, S{{[0-9]+}}}.x }}87 // expected-warning-re@-2 {{&Element{lifetime_extended_object{Array<int>, extendingDifferentTypes, S{{[0-9]+}}}.array,0 S64b,int} }}88 89 Composite const& variableAndExtended = cond ? static_cast<Composite&&>(cc) : Array<Composite>{}.array[0]; // extends `Array<Composite>` in false branch90 clang_analyzer_dump(variableAndExtended);91 // expected-warning@-1 {{&cc }}92 // expected-warning-re@-2 {{&Element{lifetime_extended_object{Array<Composite>, variableAndExtended, S{{[0-9]+}}}.array,0 S64b,struct Composite} }}93 94 int const& extendAndDangling = cond ? Array<int>{}.array[0] : Array<int>{}.front(); // extends `Array<int>` only in true branch, false branch dangles95 clang_analyzer_dump(extendAndDangling);96 // expected-warning-re@-1 {{&Element{lifetime_extended_object{Array<int>, extendAndDangling, S{{[0-9]+}}}.array,0 S64b,int} }}97 // expected-warning-re@-2 {{&Element{temp_object{Array<int>, S{{[0-9]+}}}.array,0 S64b,int} }}98}99 100struct RefAggregate {101 int const& rx;102 Composite&& ry = Composite{};103};104 105void aggregateWithReferences() {106 RefAggregate multipleExtensions = {10, Composite{}}; // extends `int` and `Composite`107 clang_analyzer_dump(multipleExtensions.rx); // expected-warning-re {{&lifetime_extended_object{int, multipleExtensions, S{{[0-9]+}}} }}108 clang_analyzer_dump(multipleExtensions.ry); // expected-warning-re {{&lifetime_extended_object{Composite, multipleExtensions, S{{[0-9]+}}} }}109 110 RefAggregate danglingAndExtended{Array<int>{}.front(), Composite{}}; // extends only `Composite`, `Array<int>` dangles111 clang_analyzer_dump(danglingAndExtended.rx); // expected-warning-re {{&Element{temp_object{Array<int>, S{{[0-9]+}}}.array,0 S64b,int} }}112 clang_analyzer_dump(danglingAndExtended.ry); // expected-warning-re {{&lifetime_extended_object{Composite, danglingAndExtended, S{{[0-9]+}}} }}113 114 int i = 10;115 RefAggregate varAndExtended{i, Composite{}}; // extends `Composite`116 clang_analyzer_dump(varAndExtended.rx); // expected-warning {{&i }}117 clang_analyzer_dump(varAndExtended.ry); // expected-warning-re {{&lifetime_extended_object{Composite, varAndExtended, S{{[0-9]+}}} }}118 119 auto const& viaReference = RefAggregate{10, Composite{}}; // extends `int`, `Composite`, and `RefAggregate`120 clang_analyzer_dump(viaReference); // expected-warning-re {{&lifetime_extended_object{RefAggregate, viaReference, S{{[0-9]+}}} }}121 clang_analyzer_dump(viaReference.rx); // expected-warning-re {{&lifetime_extended_object{int, viaReference, S{{[0-9]+}}} }}122 clang_analyzer_dump(viaReference.ry); // expected-warning-re {{&lifetime_extended_object{Composite, viaReference, S{{[0-9]+}}} }}123 124 // FIXME: clang currently support extending lifetime of object bound to reference members of aggregates,125 // that are created from default member initializer. But CFG and ExprEngine need to be updated to address this change.126 // The following expect warning: {{&lifetime_extended_object{Composite, defaultInitExtended, S{{[0-9]+}}} }}127 RefAggregate defaultInitExtended{i};128 clang_analyzer_dump(defaultInitExtended.ry); // expected-warning {{Unknown }}129}130 131void lambda() {132 auto const& lambdaRef = [capture = create<Composite>()] {};133 clang_analyzer_dump(lambdaRef); // expected-warning-re {{lifetime_extended_object{class (lambda at {{[^)]+}}), lambdaRef, S{{[0-9]+}}} }}134 135 // The capture [&refCapture = create<Composite const>()] { ... } per [expr.prim.lambda.capture] p6 equivalent to:136 // auto& refCapture = create<Composite const>(); // Well-formed, deduces auto = Composite const, and performs lifetime extension137 // [&refCapture] { ... }138 // Where 'refCapture' has the same lifetime as the lambda itself.139 // However, compilers differ: Clang lifetime-extends from C++17, GCC rejects the code, and MSVC dangles140 // See also CWG2737 (https://cplusplus.github.io/CWG/issues/2737.html)141 auto const refExtendingCapture = [&refCapture = create<Composite const>()] {142 clang_analyzer_dump(refCapture);143 // cpp14-warning-re@-1 {{&temp_object{const struct Composite, S{{[0-9]+}}} }}144 // cpp17-warning-re@-2 {{&lifetime_extended_object{const struct Composite, refExtendingCapture, S{{[0-9]+}}} }}145 };146 refExtendingCapture();147}148 149void viaStructuredBinding() {150 auto&& [x, y] = Composite{}; // extends `Composite` and binds it to unnamed decomposed object151 clang_analyzer_dump(x); // expected-warning-re {{&lifetime_extended_object{Composite, D{{[0-9]+}}, S{{[0-9]+}}}.x }}152 clang_analyzer_dump(y); // expected-warning-re {{&lifetime_extended_object{Composite, D{{[0-9]+}}, S{{[0-9]+}}}.y }}153 154 auto&& [rx, ry] = RefAggregate{10, Composite{}}; // extends `int`, `Composite`, and `RefAggregate`, and binds them to unnamed decomposed object155 clang_analyzer_dump(rx); // expected-warning-re {{&lifetime_extended_object{int, D{{[0-9]+}}, S{{[0-9]+}}} }}156 clang_analyzer_dump(ry); // expected-warning-re {{&lifetime_extended_object{Composite, D{{[0-9]+}}, S{{[0-9]+}}} }}157}158 159void propagation(bool cond) {160 int const& le = Composite{}.x;161 // May return lifetime-extended region or dangling temporary162 auto&& oneDangling = select(cond, le, 10); // does not extend lifetime of arguments163 clang_analyzer_dump(oneDangling);164 // expected-warning-re@-1 {{&lifetime_extended_object{Composite, le, S{{[0-9]+}}}.x }}165 // expected-warning-re@-2 {{&temp_object{int, S{{[0-9]+}}} }}166 167 // Always dangles168 auto&& bothDangling = select(cond, 10, 20); // does not extend lifetime of arguments169 clang_analyzer_dump(bothDangling);170 // expected-warning-re@-1 {{&temp_object{int, S{{[0-9]+}}} }}171 // expected-warning-re@-2 {{&temp_object{int, S{{[0-9]+}}} }}172}173