JonasToth updated this revision to Diff 153282.
JonasToth added a comment.
- Merge branch 'master' into check_const
Repository:
rCTE Clang Tools Extra
https://reviews.llvm.org/D45444
Files:
clang-tidy/cppcoreguidelines/CMakeLists.txt
clang-tidy/cppcoreguidelines/ConstCheck.cpp
clang-tidy/cppcoreguidelines/ConstCheck.h
clang-tidy/cppcoreguidelines/CppCoreGuidelinesTidyModule.cpp
docs/ReleaseNotes.rst
docs/clang-tidy/checks/cppcoreguidelines-const.rst
docs/clang-tidy/checks/list.rst
test/clang-tidy/cppcoreguidelines-const-pointers-as-values.cpp
test/clang-tidy/cppcoreguidelines-const-values.cpp
Index: test/clang-tidy/cppcoreguidelines-const-values.cpp
===================================================================
--- /dev/null
+++ test/clang-tidy/cppcoreguidelines-const-values.cpp
@@ -0,0 +1,557 @@
+// RUN: %check_clang_tidy %s cppcoreguidelines-const %t
+
+// ------- Provide test samples for primitive builtins ---------
+// - every 'p_*' variable is a 'potential_const_*' variable
+// - every 'np_*' variable is a 'non_potential_const_*' variable
+
+bool global;
+char np_global = 0; // globals can't be known to be const
+
+namespace foo {
+int scoped;
+float np_scoped = 1; // namespace variables are like globals
+} // namespace foo
+
+void some_function(double, wchar_t);
+
+void some_function(double np_arg0, wchar_t np_arg1) {
+ int p_local0 = 2;
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local0' of type 'int' can be declared const
+
+ int np_local0;
+ const int np_local1 = 42;
+
+ unsigned int np_local2 = 3;
+ np_local2 <<= 4;
+
+ int np_local3 = 4;
+ ++np_local3;
+ int np_local4 = 4;
+ np_local4++;
+
+ int np_local5 = 4;
+ --np_local5;
+ int np_local6 = 4;
+ np_local6--;
+}
+
+void nested_scopes() {
+ int p_local0 = 2;
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local0' of type 'int' can be declared const
+ int np_local0 = 42;
+
+ {
+ int p_local1 = 42;
+ // CHECK-MESSAGES: [[@LINE-1]]:5: warning: variable 'p_local1' of type 'int' can be declared const
+ np_local0 *= 2;
+ }
+}
+
+void some_lambda_environment_capture_all_by_reference(double np_arg0) {
+ int np_local0 = 0;
+ int p_local0 = 1;
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local0' of type 'int' can be declared const
+
+ int np_local2;
+ const int np_local3 = 2;
+
+ // Capturing all variables by reference prohibits making them const.
+ [&]() { ++np_local0; };
+
+ int p_local1 = 0;
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local1' of type 'int' can be declared const
+}
+
+void some_lambda_environment_capture_all_by_value(double np_arg0) {
+ int np_local0 = 0;
+ int p_local0 = 1;
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local0' of type 'int' can be declared const
+
+ int np_local1;
+ const int np_local2 = 2;
+
+ // Capturing by value has no influence on them.
+ [=]() { (void)p_local0; };
+
+ np_local0 += 10;
+}
+
+void function_inout_pointer(int *inout);
+void function_in_pointer(const int *in);
+
+void some_pointer_taking(int *out) {
+ int np_local0 = 42;
+ const int *const p0_np_local0 = &np_local0;
+ int *const p1_np_local0 = &np_local0;
+
+ int np_local1 = 42;
+ const int *const p0_np_local1 = &np_local1;
+ int *const p1_np_local1 = &np_local1;
+ *p1_np_local0 = 43;
+
+ int np_local2 = 42;
+ function_inout_pointer(&np_local2);
+
+ // Prevents const.
+ int np_local3 = 42;
+ out = &np_local3; // This returns and invalid address, its just about the AST
+
+ int p_local1 = 42;
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local1' of type 'int' can be declared const
+ const int *const p0_p_local1 = &p_local1;
+
+ int p_local2 = 42;
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local2' of type 'int' can be declared const
+ function_in_pointer(&p_local2);
+}
+
+void function_inout_ref(int &inout);
+void function_in_ref(const int &in);
+
+void some_reference_taking() {
+ int np_local0 = 42;
+ const int &r0_np_local0 = np_local0;
+ int &r1_np_local0 = np_local0;
+ r1_np_local0 = 43;
+ const int &r2_np_local0 = r1_np_local0;
+
+ int np_local1 = 42;
+ function_inout_ref(np_local1);
+
+ int p_local0 = 42;
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local0' of type 'int' can be declared const
+ const int &r0_p_local0 = p_local0;
+
+ int p_local1 = 42;
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local1' of type 'int' can be declared const
+ function_in_ref(p_local1);
+}
+
+double *non_const_pointer_return() {
+ double p_local0 = 0.0;
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local0' of type 'double' can be declared const
+ double np_local0 = 24.4;
+
+ return &np_local0;
+}
+
+const double *const_pointer_return() {
+ double p_local0 = 0.0;
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local0' of type 'double' can be declared const
+ double p_local1 = 24.4;
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local1' of type 'double' can be declared const
+ return &p_local1;
+}
+
+double &non_const_ref_return() {
+ double p_local0 = 0.0;
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local0' of type 'double' can be declared const
+ double np_local0 = 42.42;
+ return np_local0;
+}
+
+const double &const_ref_return() {
+ double p_local0 = 0.0;
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local0' of type 'double' can be declared const
+ double p_local1 = 24.4;
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local1' of type 'double' can be declared const
+ return p_local1;
+}
+
+double *&return_non_const_pointer_ref() {
+ double *np_local0 = nullptr;
+ return np_local0;
+}
+
+void overloaded_arguments(const int &in);
+void overloaded_arguments(int &inout);
+void overloaded_arguments(const int *in);
+void overloaded_arguments(int *inout);
+
+void function_calling() {
+ int np_local0 = 42;
+ overloaded_arguments(np_local0);
+
+ const int np_local1 = 42;
+ overloaded_arguments(np_local1);
+
+ int np_local2 = 42;
+ overloaded_arguments(&np_local2);
+
+ const int np_local3 = 42;
+ overloaded_arguments(&np_local3);
+}
+
+template <typename T>
+void define_locals(T np_arg0, T &np_arg1, int np_arg2) {
+ T np_local0 = 0;
+ np_local0 += np_arg0 * np_arg1;
+
+ T np_local1 = 42;
+ np_local0 += np_local1;
+
+ // Used as argument to an overloaded function with const and non-const.
+ T np_local2 = 42;
+ overloaded_arguments(np_local2);
+
+ int np_local4 = 42;
+ // non-template values are ok still.
+ int p_local0 = 42;
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local0' of type 'int' can be declared const
+ np_local4 += p_local0;
+}
+
+void template_instantiation() {
+ const int np_local0 = 42;
+ int np_local1 = 42;
+
+ define_locals(np_local0, np_local1, np_local0);
+ define_locals(np_local1, np_local1, np_local1);
+}
+
+struct ConstNonConstClass {
+ ConstNonConstClass();
+ ConstNonConstClass(double &np_local0);
+ double nonConstMethod() {}
+ double constMethod() const {}
+ double modifyingMethod(double &np_arg0) const;
+
+ double NonConstMember;
+ const double ConstMember;
+
+ double &NonConstMemberRef;
+ const double &ConstMemberRef;
+
+ double *NonConstMemberPtr;
+ const double *ConstMemberPtr;
+};
+
+void direct_class_access() {
+ ConstNonConstClass np_local0;
+
+ np_local0.constMethod();
+ np_local0.nonConstMethod();
+
+ ConstNonConstClass p_local0;
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local0' of type 'ConstNonConstClass' can be declared const
+ p_local0.constMethod();
+
+ ConstNonConstClass p_local1;
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local1' of type 'ConstNonConstClass' can be declared const
+ double np_local1;
+ p_local1.modifyingMethod(np_local1);
+
+ double np_local2;
+ ConstNonConstClass p_local2(np_local2);
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local2' of type 'ConstNonConstClass' can be declared const
+
+ ConstNonConstClass np_local3;
+ np_local3.NonConstMember = 42.;
+
+ ConstNonConstClass np_local4;
+ np_local4.NonConstMemberRef = 42.;
+
+ ConstNonConstClass p_local3;
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local3' of type 'ConstNonConstClass' can be declared const
+ const double val0 = p_local3.NonConstMember;
+ const double val1 = p_local3.NonConstMemberRef;
+ const double val2 = *p_local3.NonConstMemberPtr;
+
+ ConstNonConstClass p_local4;
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local4' of type 'ConstNonConstClass' can be declared const
+ *np_local4.NonConstMemberPtr = 42.;
+}
+
+void class_access_array() {
+ ConstNonConstClass np_local0[2];
+ np_local0[0].constMethod();
+ np_local0[1].constMethod();
+ np_local0[1].nonConstMethod();
+
+ ConstNonConstClass p_local0[2];
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local0' of type 'ConstNonConstClass [2]' can be declared const
+ p_local0[0].constMethod();
+ np_local0[1].constMethod();
+}
+
+struct OperatorsAsConstAsPossible {
+ OperatorsAsConstAsPossible &operator+=(const OperatorsAsConstAsPossible &rhs);
+ OperatorsAsConstAsPossible operator+(const OperatorsAsConstAsPossible &rhs) const;
+};
+
+struct NonConstOperators {
+};
+NonConstOperators operator+(NonConstOperators &lhs, NonConstOperators &rhs);
+NonConstOperators operator-(NonConstOperators lhs, NonConstOperators rhs);
+
+void internal_operator_calls() {
+ OperatorsAsConstAsPossible np_local0;
+ OperatorsAsConstAsPossible np_local1;
+ OperatorsAsConstAsPossible p_local0;
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local0' of type 'OperatorsAsConstAsPossible' can be declared const
+ OperatorsAsConstAsPossible p_local1;
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local1' of type 'OperatorsAsConstAsPossible' can be declared const
+
+ np_local0 += p_local0;
+ np_local1 = p_local0 + p_local1;
+
+ NonConstOperators np_local2;
+ NonConstOperators np_local3;
+ NonConstOperators np_local4;
+
+ np_local2 = np_local3 + np_local4;
+
+ NonConstOperators p_local2;
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local2' of type 'NonConstOperators' can be declared const
+ NonConstOperators p_local3 = p_local2 - p_local2;
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local3' of type 'NonConstOperators' can be declared const
+}
+
+struct MyVector {
+ double *begin();
+ const double *begin() const;
+
+ double *end();
+ const double *end() const;
+
+ double &operator[](int index);
+ double operator[](int index) const;
+
+ double values[100];
+};
+
+void vector_usage() {
+ double np_local0[10];
+ np_local0[5] = 42.;
+
+ MyVector np_local1;
+ np_local1[5] = 42.;
+
+ double p_local0[10] = {0., 1., 2., 3., 4., 5., 6., 7., 8., 9.};
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local0' of type 'double [10]' can be declared const
+ double p_local1 = p_local0[5];
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local1' of type 'double' can be declared const
+
+ // The following subscript calls suprisingly choose the non-const operator
+ // version.
+ MyVector np_local2;
+ double p_local2 = np_local2[42];
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local2' of type 'double' can be declared const
+
+ MyVector np_local3;
+ const double np_local4 = np_local3[42];
+
+ // This subscript results in const overloaded operator.
+ const MyVector np_local5{};
+ double p_local3 = np_local5[42];
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local3' of type 'double' can be declared const
+}
+
+void const_handle(const double &np_local0);
+void const_handle(const double *np_local0);
+
+void non_const_handle(double &np_local0);
+void non_const_handle(double *np_local0);
+
+void handle_from_array() {
+ // Non-const handle from non-const array forbids declaring the array as const
+ double np_local0[10] = {0., 1., 2., 3., 4., 5., 6., 7., 8., 9.};
+ double *p_local0 = &np_local0[1]; // Could be `double *const`, but warning deactivated by default
+
+ double np_local1[10] = {0., 1., 2., 3., 4., 5., 6., 7., 8., 9.};
+ double &non_const_ref = np_local1[1];
+ non_const_ref = 42.;
+
+ double np_local2[10] = {0., 1., 2., 3., 4., 5., 6., 7., 8., 9.};
+ double *np_local3;
+ np_local3 = &np_local2[5];
+
+ double np_local4[10] = {0., 1., 2., 3., 4., 5., 6., 7., 8., 9.};
+ non_const_handle(np_local4[2]);
+ double np_local5[10] = {0., 1., 2., 3., 4., 5., 6., 7., 8., 9.};
+ non_const_handle(&np_local5[2]);
+
+ // Constant handles are ok
+ double p_local1[10] = {0., 1., 2., 3., 4., 5., 6., 7., 8., 9.};
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local1' of type 'double [10]' can be declared const
+ const double *p_local2 = &p_local1[2]; // Could be `const double *const`, but warning deactivated by default
+
+ double p_local3[10] = {0., 1., 2., 3., 4., 5., 6., 7., 8., 9.};
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local3' of type 'double [10]' can be declared const
+ const double &const_ref = p_local3[2];
+
+ double p_local4[10] = {0., 1., 2., 3., 4., 5., 6., 7., 8., 9.};
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local4' of type 'double [10]' can be declared const
+ const double *const_ptr;
+ const_ptr = &p_local4[2];
+
+ double p_local5[10] = {0., 1., 2., 3., 4., 5., 6., 7., 8., 9.};
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local5' of type 'double [10]' can be declared const
+ const_handle(p_local5[2]);
+ double p_local6[10] = {0., 1., 2., 3., 4., 5., 6., 7., 8., 9.};
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local6' of type 'double [10]' can be declared const
+ const_handle(&p_local6[2]);
+}
+
+void range_for() {
+ int np_local0[2] = {1, 2};
+ for (int &non_const_ref : np_local0) {
+ non_const_ref = 42;
+ }
+
+ int np_local1[2] = {1, 2};
+ for (auto &non_const_ref : np_local1) {
+ non_const_ref = 43;
+ }
+
+ int np_local2[2] = {1, 2};
+ for (auto &&non_const_ref : np_local2) {
+ non_const_ref = 44;
+ }
+
+ // FIXME the warning message is suboptimal. It could be defined as
+ // `int *const np_local3[2]` because the pointers are not reseated.
+ // But this is not easily deducable from the warning.
+ int *np_local3[2] = {&np_local0[0], &np_local0[1]};
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'np_local3' of type 'int *[2]' can be declared const
+ for (int *non_const_ptr : np_local3) {
+ *non_const_ptr = 45;
+ }
+
+ // FIXME same as above, but silenced
+ int *const np_local4[2] = {&np_local0[0], &np_local0[1]};
+ for (auto *non_const_ptr : np_local4) {
+ *non_const_ptr = 46;
+ }
+
+ int p_local0[2] = {1, 2};
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local0' of type 'int [2]' can be declared const
+ for (int value : p_local0) {
+ // CHECK-MESSAGES: [[@LINE-1]]:8: warning: variable 'value' of type 'int' can be declared const
+ }
+
+ int p_local1[2] = {1, 2};
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local1' of type 'int [2]' can be declared const
+ for (const int &const_ref : p_local1) {
+ }
+
+ int *p_local2[2] = {&np_local0[0], &np_local0[1]};
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local2' of type 'int *[2]' can be declared const
+ for (const int *con_ptr : p_local2) {
+ }
+
+ int *p_local3[2] = {nullptr, nullptr};
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local3' of type 'int *[2]' can be declared const
+ for (const auto *con_ptr : p_local3) {
+ }
+}
+
+inline void *operator new(decltype(sizeof(void *)), void *p) { return p; }
+
+struct Value {
+};
+void placement_new() {
+ Value Mem;
+ Value *V = new (&Mem) Value;
+}
+
+struct ModifyingConversion {
+ operator int() { return 15; }
+};
+struct NonModifyingConversion {
+ operator int() const { return 15; }
+};
+void conversion_operators() {
+ ModifyingConversion np_local0;
+ NonModifyingConversion p_local0;
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local0' of type 'NonModifyingConversion' can be declared const
+
+ int np_local1 = np_local0;
+ np_local1 = p_local0;
+}
+
+void casts() {
+ decltype(sizeof(void *)) p_local0 = 42;
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local0' of type 'decltype(sizeof(void *))' (aka 'unsigned long') can be declared const
+ auto np_local0 = reinterpret_cast<void *>(p_local0);
+ np_local0 = nullptr;
+
+ int p_local1 = 43;
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local1' of type 'int' can be declared const
+ short p_local2 = static_cast<short>(p_local1);
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local2' of type 'short' can be declared const
+
+ int np_local1 = p_local2;
+ int &np_local2 = static_cast<int &>(np_local1);
+ np_local2 = 5;
+}
+
+void ternary_operator() {
+ int np_local0 = 1, np_local1 = 2;
+ int &np_local2 = true ? np_local0 : np_local1;
+ np_local2 = 2;
+
+ int p_local0 = 3, np_local3 = 5;
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local0' of type 'int' can be declared const
+ const int &np_local4 = true ? p_local0 : ++np_local3;
+
+ int np_local5[3] = {1, 2, 3};
+ int &np_local6 = np_local5[1] < np_local5[2] ? np_local5[0] : np_local5[2];
+ np_local6 = 42;
+
+ int np_local7[3] = {1, 2, 3};
+ int *np_local8 = np_local7[1] < np_local7[2] ? &np_local7[0] : &np_local7[2];
+ *np_local8 = 42;
+}
+
+// taken from http://www.cplusplus.com/reference/type_traits/integral_constant/
+template <typename T, T v>
+struct integral_constant {
+ static constexpr T value = v;
+ using value_type = T;
+ using type = integral_constant<T, v>;
+ constexpr operator T() { return v; }
+};
+
+template <typename T>
+struct is_integral : integral_constant<bool, false> {};
+template <>
+struct is_integral<int> : integral_constant<bool, true> {};
+
+template <typename T>
+struct not_integral : integral_constant<bool, false> {};
+template <>
+struct not_integral<double> : integral_constant<bool, true> {};
+
+// taken from http://www.cplusplus.com/reference/type_traits/enable_if/
+template <bool Cond, typename T = void>
+struct enable_if {};
+
+template <typename T>
+struct enable_if<true, T> { using type = T; };
+
+template <typename T>
+struct TMPClass {
+ T alwaysConst() const { return T{}; }
+
+ template <typename T2 = T, typename = typename enable_if<is_integral<T2>::value>::type>
+ T sometimesConst() const { return T{}; }
+
+ template <typename T2 = T, typename = typename enable_if<not_integral<T2>::value>::type>
+ T sometimesConst() { return T{}; }
+};
+
+void meta_type() {
+ TMPClass<int> p_local0;
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local0' of type 'TMPClass<int>' can be declared const
+ p_local0.alwaysConst();
+ p_local0.sometimesConst();
+
+ TMPClass<double> p_local1;
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local1' of type 'TMPClass<double>' can be declared const
+ p_local1.alwaysConst();
+
+ TMPClass<double> np_local0;
+ np_local0.alwaysConst();
+ np_local0.sometimesConst();
+}
Index: test/clang-tidy/cppcoreguidelines-const-pointers-as-values.cpp
===================================================================
--- /dev/null
+++ test/clang-tidy/cppcoreguidelines-const-pointers-as-values.cpp
@@ -0,0 +1,11 @@
+// RUN: %check_clang_tidy %s cppcoreguidelines-const %t \
+// RUN: -config='{CheckOptions: \
+// RUN: [{key: "cppcoreguidelines-const.AnalyzeValues", value: 1},\
+// RUN: {key: "cppcoreguidelines-const.WarnPointersAsValues", value: 1}]}' \
+// RUN: --
+
+void potential_const_pointer() {
+ double np_local0[10] = {0., 1., 2., 3., 4., 5., 6., 7., 8., 9.};
+ double *p_local0 = &np_local0[1];
+ // CHECK-MESSAGES: [[@LINE-1]]:3: warning: variable 'p_local0' of type 'double *' can be declared const
+}
Index: docs/clang-tidy/checks/list.rst
===================================================================
--- docs/clang-tidy/checks/list.rst
+++ docs/clang-tidy/checks/list.rst
@@ -77,6 +77,7 @@
cert-oop11-cpp (redirects to performance-move-constructor-init) <cert-oop11-cpp>
cppcoreguidelines-avoid-goto
cppcoreguidelines-c-copy-assignment-signature (redirects to misc-unconventional-assign-operator) <cppcoreguidelines-c-copy-assignment-signature>
+ cppcoreguidelines-const
cppcoreguidelines-interfaces-global-init
cppcoreguidelines-narrowing-conversions
cppcoreguidelines-no-malloc
Index: docs/clang-tidy/checks/cppcoreguidelines-const.rst
===================================================================
--- /dev/null
+++ docs/clang-tidy/checks/cppcoreguidelines-const.rst
@@ -0,0 +1,68 @@
+.. title:: clang-tidy - cppcoreguidelines-const
+
+cppcoreguidelines-const
+=======================
+
+This check implements detection of local variables that could be declared as
+``const``, but are not. Declaring variables as ``const`` is required by many
+coding guidelines for example
+`CppCoreGuidelines ES.25 <https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#es25-declare-an-object-const-or-constexpr-unless-you-want-to-modify-its-value-later-on>`_
+and `High Integrity C++ 7.1.2 <http://www.codingstandard.com/rule/7-1-2-use-const-whenever-possible/>`_.
+
+Please note that this analysis is type based only. Variables that are not modified
+but non-const handles might escape out of the scope are not diagnosed as potential
+``const``.
+
+.. code-block:: c++
+
+ // Declare a variable, which is not ``const`` ...
+ int i = 42;
+ // but use it as read-only. This means that `i` can be declared ``const``.
+ int result = i * i;
+
+The check analyzes values, pointers and references (if configured that way).
+For better understanding some code samples:
+
+.. code-block:: c++
+
+ // Normal values like built-ins or objects.
+ int potential_const_int = 42;
+ int copy_of_value = potential_const_int;
+
+ MyClass could_be_const;
+ could_be_const.const_qualified_method();
+
+ // References can be declared const as well.
+ int &reference_value = potential_const_int;
+ int another_copy = reference_value;
+
+ // Similar behaviour for pointers.
+ int *pointer_variable = &potential_const_int;
+ int last_copy = *pointer_variable;
+
+
+Options
+-------
+
+.. option:: AnalyzeValues (default = 1)
+
+ Enable or disable the analysis of ordinary value variables, like ``int i = 42;``
+
+.. option:: AnalyzeReferences (default = 1)
+
+ Enable or disable the analysis of reference variables, like ``int &ref = i;``
+
+.. option:: WarnPointersAsValues (default = 0)
+
+ This option enables the suggestion for ``const`` of the pointer itself.
+ Pointer values have two possibilities to be ``const``, the pointer itself
+ and the value pointing to.
+
+ .. code-block:: c++
+
+ const int value = 42;
+ const int * const pointer_variable = &value;
+
+ // The following operations are forbidden for `pointer_variable`.
+ // *pointer_variable = 44;
+ // pointer_variable = nullptr;
Index: docs/ReleaseNotes.rst
===================================================================
--- docs/ReleaseNotes.rst
+++ docs/ReleaseNotes.rst
@@ -102,6 +102,11 @@
with looping constructs. Every backward jump is rejected. Forward jumps are
only allowed in nested loops.
+- New :doc:`cppcoreguidelines-const
+ <clang-tidy/checks/cppcoreguidelines-const>` check
+
+ Suggest adding ``const`` to unmodified local variables.
+
- New :doc:`cppcoreguidelines-narrowing-conversions
<clang-tidy/checks/cppcoreguidelines-narrowing-conversions>` check
Index: clang-tidy/cppcoreguidelines/CppCoreGuidelinesTidyModule.cpp
===================================================================
--- clang-tidy/cppcoreguidelines/CppCoreGuidelinesTidyModule.cpp
+++ clang-tidy/cppcoreguidelines/CppCoreGuidelinesTidyModule.cpp
@@ -12,6 +12,7 @@
#include "../ClangTidyModuleRegistry.h"
#include "../misc/UnconventionalAssignOperatorCheck.h"
#include "AvoidGotoCheck.h"
+#include "ConstCheck.h"
#include "InterfacesGlobalInitCheck.h"
#include "NarrowingConversionsCheck.h"
#include "NoMallocCheck.h"
@@ -39,6 +40,8 @@
void addCheckFactories(ClangTidyCheckFactories &CheckFactories) override {
CheckFactories.registerCheck<AvoidGotoCheck>(
"cppcoreguidelines-avoid-goto");
+ CheckFactories.registerCheck<ConstCheck>(
+ "cppcoreguidelines-const");
CheckFactories.registerCheck<InterfacesGlobalInitCheck>(
"cppcoreguidelines-interfaces-global-init");
CheckFactories.registerCheck<NarrowingConversionsCheck>(
Index: clang-tidy/cppcoreguidelines/ConstCheck.h
===================================================================
--- /dev/null
+++ clang-tidy/cppcoreguidelines/ConstCheck.h
@@ -0,0 +1,57 @@
+//===--- ConstCheck.h - clang-tidy-------------------------------*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_CPPCOREGUIDELINES_CONSTCHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_CPPCOREGUIDELINES_CONSTCHECK_H
+
+#include "../ClangTidy.h"
+#include "../utils/ExprMutationAnalyzer.h"
+
+namespace clang {
+namespace tidy {
+
+namespace utils {
+class ExprMutationAnalyzer;
+}
+
+namespace cppcoreguidelines {
+
+/// This check warns for every variable, that could be declared as const, but
+/// isn't.
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/cppcoreguidelines-const.html
+class ConstCheck : public ClangTidyCheck {
+public:
+ ConstCheck(StringRef Name, ClangTidyContext *Context)
+ : ClangTidyCheck(Name, Context),
+ AnalyzeValues(Options.get("AnalyzeValues", 1)),
+ AnalyzeReferences(Options.get("AnalyzeReferences", 1)),
+ WarnPointersAsValues(Options.get("WarnPointersAsValues", 0)) {}
+
+ void storeOptions(ClangTidyOptions::OptionMap &Opts) override;
+ void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+ void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+
+private:
+ void registerScope(const CompoundStmt *Scope, ASTContext *Context);
+
+ using MutationAnalyzer = std::unique_ptr<utils::ExprMutationAnalyzer>;
+ llvm::DenseMap<const CompoundStmt *, MutationAnalyzer> ScopesCache;
+
+ const bool AnalyzeValues;
+ const bool AnalyzeReferences;
+ const bool WarnPointersAsValues;
+};
+
+} // namespace cppcoreguidelines
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_CPPCOREGUIDELINES_CONSTCHECK_H
Index: clang-tidy/cppcoreguidelines/ConstCheck.cpp
===================================================================
--- /dev/null
+++ clang-tidy/cppcoreguidelines/ConstCheck.cpp
@@ -0,0 +1,207 @@
+//===--- ConstCheck.cpp - clang-tidy---------------------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "ConstCheck.h"
+// #include "../utils/ASTUtils.h"
+// #include "../utils/DeclRefExprUtils.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+#include <iostream>
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+namespace cppcoreguidelines {
+
+/*
+ * NOTE: This massive comment will be removed before committing. It serves as
+ * notebook on what to keep an eye on for now.
+ *
+ * General Thoughts
+ * ================
+ *
+ * For now: Only local variables are considered. Globals/namespace variables,
+ * paramters and class members are not analyzed.
+ * Parameters have a check already: readability-non-const-parameter
+ *
+ *
+ * Handle = either a pointer or reference
+ * Value = everything else (Type variable_name;)
+ *
+ * Value Semantic
+ * ==============
+ * - it is neither global nor namespace level + CHECK
+ * - it never gets assigned to after initialization + CHECK
+ * -> every uninitialized variable can not be const + CHECK
+ * - no non-const handle is created with it + CHECK
+ * - no non-const pointer from it + CHECK
+ * - no non-const pointer argument + CHECK
+ * - no non-const reference from it + CHECK
+ * - no non-const reference argument + CHECK
+ * - no non-const capture by reference in a lambda + CHECK
+ * - it is not returned as non-const handle from a function + CHECK
+ * - it address is not assigned to an out pointer parameter + CHECK
+ *
+ * primitive Builtins
+ * ----------------
+ * - it is not modified with an operator (++i,i++,--i,i--) + CHECK
+ * - it is not modified with an operator-assignment + CHECK
+ *
+ * objects
+ * -------
+ * - there is no non-const access to a member
+ * - there is no call to a non-const method + CHECK
+ * - there is no call to an non-const overloaded operator + CHECK
+ * - there is no non-const iterator created from this type + CHECK
+ * (std::begin and friends)
+ *
+ * arrays
+ * ------
+ * - there is no non-const operator[] access + CHECK
+ * - there is no non-const handle creation of one of the elements + CHECK
+ * - there is no non-const iterator created from this type + CHECK
+ * (std::begin and friends)
+ *
+ * templated variables
+ * -------------------
+ * - one can not reason about templated variables, because every sensible
+ * operation is overloadable and different instantiations will result
+ * in types with different const-properties.
+ * - Example: operator+(T& lhs, T& rhs) -> modification might occur for this
+ * type
+ * -> this fordbids `val = val1 + val2` val1 and val2 to be const
+ * - only concepts give possibility to infer constness of templated variables
+ *
+ * Handle Semantic
+ * ===============
+ * - modification of the pointee prohibit constness
+ * - Handles follow the typ of the pointee
+ *
+ * - no assignment to the target of the handle
+ *
+ * pointers
+ * --------
+ * - match both for value and handle semantic
+ *
+ * references
+ * ----------
+ * - only handle semantic applies
+ * - references to templated types suffer from the same problems as templated
+ * values
+ *
+ * forwarding reference
+ * --------------------
+ * - same as references?
+ *
+ * Implementation strategy
+ * =======================
+ *
+ * - Register every declared local variable/constant with value semantic.
+ * (pointers, values)
+ * Store if they can be made const.
+ * (const int i = 10 : no,
+ * int *const = &i : no,
+ * int i = 10 : yes, -> const int i = 10
+ * int *p_i = &i : yes, -> int *const p_i = &i)
+ * - Register every declared local variable/constant with handle semantic.
+ * (pointers, references)
+ * Store if they can be made const, meaning if they can be a const target
+ * (const int *cp_i = &i : no,
+ * const int &cr_i = i : no,
+ * int *p_i = &i : yes, -> const int *p_i = &i
+ * int &r_i = i : yes, -> const int &r_i = i)
+ * - Keep 2 dictionaries for values and handles
+ *
+ * - Match operations/events that forbid values to be const -> mark then 'no'
+ * - Match operations/events that forbid handles to be const -> mark then 'no'
+ *
+ * - once the translation unit is finished, determine what can be const, by
+ * just iterating over all keys and check if they map to 'true'.
+ * - values that can be const -> emit warning for their type and name
+ * - handles that can be const -> emit warning for the pointee type and name
+ * - ignore the rest
+ *
+ */
+
+namespace {
+AST_MATCHER(VarDecl, isLocal) { return Node.isLocalVarDecl(); }
+} // namespace
+
+void ConstCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
+ Options.store(Opts, "AnalyzeValues", AnalyzeValues);
+ Options.store(Opts, "AnalyzeReferences", AnalyzeReferences);
+ Options.store(Opts, "WarnPointersAsValues", WarnPointersAsValues);
+}
+
+void ConstCheck::registerMatchers(MatchFinder *Finder) {
+ if (!getLangOpts().CPlusPlus)
+ return;
+
+ const auto ConstType = hasType(isConstQualified());
+ const auto ConstReference = hasType(references(isConstQualified()));
+ const auto TemplateType = anyOf(hasType(templateTypeParmType()),
+ hasType(substTemplateTypeParmType()));
+
+ // Match local variables, that could be const.
+ // Example: `int i = 10`, `int i` (will be used if program is correct)
+ const auto LocalValDecl = varDecl(allOf(
+ isLocal(), hasInitializer(anything()), unless(ConstType),
+ unless(ConstReference), unless(TemplateType), unless(isImplicit())));
+
+ // Match the function scope for which the analysis of all local variables
+ // shall be run.
+ const auto FunctionScope =
+ functionDecl(allOf(hasBody(compoundStmt().bind("scope")),
+ findAll(LocalValDecl.bind("new-local-value"))));
+ Finder->addMatcher(FunctionScope, this);
+}
+
+void ConstCheck::check(const MatchFinder::MatchResult &Result) {
+ if (!getLangOpts().CPlusPlus)
+ return;
+
+ const auto *Scope = Result.Nodes.getNodeAs<CompoundStmt>("scope");
+ assert(Scope && "Did not match scope for local variable");
+ registerScope(Scope, Result.Context);
+
+ const auto *Variable = Result.Nodes.getNodeAs<VarDecl>("new-local-value");
+ assert(Variable && "Did not match local variable definition");
+
+ // Each variable can only in one category: Value, Pointer, Reference.
+ // Analysis can be controlled for every category.
+ if (Variable->getType()->isReferenceType() && !AnalyzeReferences)
+ return;
+
+ if (Variable->getType()->isPointerType() && !WarnPointersAsValues)
+ return;
+
+ if (!AnalyzeValues)
+ return;
+
+ // Offload const-analysis to utility function.
+ if (ScopesCache[Scope]->isMutated(Variable))
+ return;
+
+ // TODO Implement automatic code transformation to add the const.
+ diag(Variable->getLocStart(), "variable %0 of type %1 can be declared const")
+ << Variable << Variable->getType();
+}
+
+void ConstCheck::registerScope(const CompoundStmt *Scope, ASTContext *Context) {
+ if (ScopesCache.find(Scope) == ScopesCache.end()) {
+ ScopesCache.insert(std::make_pair(
+ Scope, llvm::make_unique<utils::ExprMutationAnalyzer>(Scope, Context)));
+ }
+}
+
+} // namespace cppcoreguidelines
+} // namespace tidy
+} // namespace clang
Index: clang-tidy/cppcoreguidelines/CMakeLists.txt
===================================================================
--- clang-tidy/cppcoreguidelines/CMakeLists.txt
+++ clang-tidy/cppcoreguidelines/CMakeLists.txt
@@ -2,6 +2,7 @@
add_clang_library(clangTidyCppCoreGuidelinesModule
AvoidGotoCheck.cpp
+ ConstCheck.cpp
CppCoreGuidelinesTidyModule.cpp
InterfacesGlobalInitCheck.cpp
NarrowingConversionsCheck.cpp
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