1 // PR c++/60049 - Right and left shift undefined behavior not an error 2 // in a constexpr 3 // { dg-do compile { target c++11 } } 4 // { dg-additional-options "-Wno-shift-negative-value -Wno-shift-count-negative -Wno-shift-count-overflow" } 5 6 constexpr int f1 (int n) { return 1 << n; } // { dg-error "shift expression" } 7 constexpr int f2 (int n) { return 1 << n; } // { dg-error "shift expression" } 8 constexpr int f3 (int n) { return n << 1; } // { dg-error "shift expression" "" { target c++17_down } } 9 constexpr int f4 (int n) { return 1 >> n; } // { dg-error "shift expression" } 10 constexpr int f5 (int n) { return 1 >> n; } // { dg-error "shift expression" } 11 12 constexpr int X = __CHAR_BIT__ * sizeof (int) + 1; 13 14 constexpr int x1 = f1 (X); // { dg-message "in .constexpr. expansion of" } 15 constexpr int x2 = f2 (-1); // { dg-message "in .constexpr. expansion of" } 16 constexpr int x3 = f3 (-1); // { dg-message "in .constexpr. expansion of" "" { target c++17_down } } 17 constexpr int x4 = f4 (X); // { dg-message "in .constexpr. expansion of" } 18 constexpr int x5 = f5 (-1); // { dg-message "in .constexpr. expansion of" } 19 20 constexpr int y1 = 1 << X; // { dg-error "shift expression" } 21 constexpr int y2 = 1 << -1; // { dg-error "shift expression" } 22 constexpr int y3 = -1 << 1; // { dg-error "shift expression" "" { target c++17_down } } 23 constexpr int y4 = 1 >> X; // { dg-error "shift expression" } 24 constexpr int y5 = 1 >> -1; // { dg-error "shift expression" } 25