40 lines · cpp
1// RUN: %clang_cc1 -std=c++17 -verify %s2 3template<typename T> int not_constexpr() { return T::error; }4template<typename T> constexpr int is_constexpr() { return T::error; } // expected-error {{'::'}}5 6template<typename T> int not_constexpr_var = T::error;7template<typename T> constexpr int is_constexpr_var = T::error; // expected-error {{'::'}}8template<typename T> const int is_const_var = T::error; // expected-error {{'::'}}9template<typename T> const volatile int is_const_volatile_var = T::error;10template<typename T> T is_dependent_var = T::error; // expected-error {{'::'}}11template<typename T> int &is_reference_var = T::error; // expected-error {{'::'}}12template<typename T> float is_float_var = T::error;13 14void test() {15 // Do not instantiate functions referenced in unevaluated operands...16 (void)sizeof(not_constexpr<long>());17 (void)sizeof(is_constexpr<long>());18 (void)sizeof(not_constexpr_var<long>);19 (void)sizeof(is_constexpr_var<long>);20 (void)sizeof(is_const_var<long>);21 (void)sizeof(is_const_volatile_var<long>);22 (void)sizeof(is_dependent_var<long>);23 (void)sizeof(is_dependent_var<const long>);24 (void)sizeof(is_reference_var<long>);25 (void)sizeof(is_float_var<long>);26 27 // ... but do if they are potentially constant evaluated, and refer to28 // constexpr functions or to variables usable in constant expressions.29 (void)sizeof(int{not_constexpr<int>()});30 (void)sizeof(int{is_constexpr<int>()}); // expected-note {{instantiation of}}31 (void)sizeof(int{not_constexpr_var<int>});32 (void)sizeof(int{is_constexpr_var<int>}); // expected-note {{instantiation of}}33 (void)sizeof(int{is_const_var<int>}); // expected-note {{instantiation of}}34 (void)sizeof(int{is_const_volatile_var<int>});35 (void)sizeof(int{is_dependent_var<int>});36 (void)sizeof(int{is_dependent_var<const int>}); // expected-note {{instantiation of}}37 (void)sizeof(int{is_reference_var<int>}); // expected-note {{instantiation of}}38 (void)sizeof(int{is_float_var<int>}); // expected-error {{cannot be narrowed}} expected-note {{cast}}39}40