clang/test/SemaCXX/ms-constexpr-invalid.cpp

   1 // RUN: %clang_cc1 -fms-compatibility -fms-compatibility-version=19.33 -std=c++20 -verify %s
   2 // RUN: %clang_cc1 -fms-compatibility -fms-compatibility-version=19.33 -std=c++17 -verify %s
   3
   4 // Check explicitly invalid code
   5
   6 void runtime() {} // expected-note {{declared here}}
   7
   8 [[msvc::constexpr]] void f0() { runtime(); } // expected-error {{constexpr function never produces a constant expression}} \
   9                                              // expected-note {{non-constexpr function 'runtime' cannot be used in a constant expression}}
  10 [[msvc::constexpr]] constexpr void f1() {} // expected-error {{attribute 'msvc::constexpr' cannot be applied to the constexpr function 'f1'}}
  11 #if __cplusplus >= 202202L
  12 [[msvc::constexpr]] consteval void f2() {} // expected-error {{attribute 'msvc::constexpr' cannot be applied to the consteval function 'f1'}}
  13 #endif
  14
  15 struct B1 {};
  16 struct D1 : virtual B1 { // expected-note {{virtual base class declared here}}
  17     [[msvc::constexpr]] D1() {} // expected-error {{constexpr constructor not allowed in struct with virtual base class}}
  18 };
  19
  20 struct [[msvc::constexpr]] S2{}; // expected-error {{'constexpr' attribute only applies to functions and return statements}}
  21
  22 // Check invalid code mixed with valid code
  23
  24 [[msvc::constexpr]] int f4(int x) { return x > 1 ? 1 + f4(x / 2) : 0; } // expected-note {{non-constexpr function 'f4' cannot be used in a constant expression}} \
  25                                                                         // expected-note {{declared here}} \
  26                                                                         // expected-note {{declared here}} \
  27                                                                         // expected-note {{declared here}}
  28 constexpr bool f5() { [[msvc::constexpr]] return f4(32) == 5; } // expected-note {{in call to 'f4(32)'}}
  29 static_assert(f5()); // expected-error {{static assertion expression is not an integral constant expression}} \
  30                      // expected-note {{in call to 'f5()'}}
  31
  32 int f6(int x) { [[msvc::constexpr]] return x > 1 ? 1 + f6(x / 2) : 0; } // expected-note {{declared here}} \
  33                                                                         // expected-note {{declared here}}
  34 constexpr bool f7() { [[msvc::constexpr]] return f6(32) == 5; } // expected-error {{constexpr function never produces a constant expression}} \
  35                                                                 // expected-note {{non-constexpr function 'f6' cannot be used in a constant expression}} \
  36                                                                 // expected-note {{non-constexpr function 'f6' cannot be used in a constant expression}}
  37 static_assert(f7()); // expected-error {{static assertion expression is not an integral constant expression}} \
  38                      // expected-note {{in call to 'f7()'}}
  39
  40 constexpr bool f8() { // expected-error {{constexpr function never produces a constant expression}}
  41     [[msvc::constexpr]] f4(32); // expected-error {{'constexpr' attribute only applies to functions and return statements}} \
  42                                 // expected-note {{non-constexpr function 'f4' cannot be used in a constant expression}} \
  43                                 // expected-note {{non-constexpr function 'f4' cannot be used in a constant expression}}
  44     [[msvc::constexpr]] int i5 = f4(32); // expected-error {{'constexpr' attribute only applies to functions and return statements}}
  45     return i5 == 5;
  46 }
  47 static_assert(f8()); // expected-error {{static assertion expression is not an integral constant expression}} \
  48                      // expected-note {{in call to 'f8()'}}
  49
  50 #if __cplusplus == 201702L
  51 struct S1 { [[msvc::constexpr]] virtual bool vm() const { return true; } }; // expected-error {{attribute 'msvc::constexpr' ignored, it only applies to function definitions and return statements}}
  52 #endif