clang/test/SemaCXX/shift.cpp

   1 // RUN: %clang_cc1 -Wall -Wno-unused-but-set-variable -Wshift-sign-overflow -ffreestanding -fsyntax-only -verify=expected,cxx17 -std=c++17 %s
   2 // RUN: %clang_cc1 -Wall -Wno-unused-but-set-variable -Wshift-sign-overflow -ffreestanding -fsyntax-only -verify=expected,cxx2a -std=c++2a %s
   3
   4 #include <limits.h>
   5
   6 #define WORD_BIT (sizeof(int) * CHAR_BIT)
   7
   8 enum {
   9   X = 1 << 0,
  10   Y = 1 << 1,
  11   Z = 1 << 2
  12 };
  13
  14 void test() {
  15   char c;
  16
  17   c = 0 << 0;
  18   c = 0 << 1;
  19   c = 1 << 0;
  20   c = 1 << -0;
  21   c = 1 >> -0;
  22   c = 1 << -1; // expected-warning {{shift count is negative}}
  23   c = 1 >> -1; // expected-warning {{shift count is negative}}
  24   c = 1 << (unsigned)-1; // expected-warning {{shift count >= width of type}}
  25                          // expected-warning@-1 {{implicit conversion from 'int' to 'char' changes value from -2147483648 to 0}}
  26   c = 1 >> (unsigned)-1; // expected-warning {{shift count >= width of type}}
  27   c = 1 << c;
  28   c <<= 0;
  29   c >>= 0;
  30   c <<= 1;
  31   c >>= 1;
  32   c <<= -1; // expected-warning {{shift count is negative}}
  33   c >>= -1; // expected-warning {{shift count is negative}}
  34   c <<= 999999; // expected-warning {{shift count >= width of type}}
  35   c >>= 999999; // expected-warning {{shift count >= width of type}}
  36   c <<= CHAR_BIT; // expected-warning {{shift count >= width of type}}
  37   c >>= CHAR_BIT; // expected-warning {{shift count >= width of type}}
  38   c <<= CHAR_BIT+1; // expected-warning {{shift count >= width of type}}
  39   c >>= CHAR_BIT+1; // expected-warning {{shift count >= width of type}}
  40   (void)((long)c << CHAR_BIT);
  41
  42   int i;
  43   i = 1 << (WORD_BIT - 2);
  44   i = 2 << (WORD_BIT - 1); // cxx17-warning {{bits to represent, but 'int' only has}}
  45   i = 1 << (WORD_BIT - 1); // cxx17-warning {{sets the sign bit of the shift expression}}
  46   i = -1 << (WORD_BIT - 1); // cxx17-warning {{shifting a negative signed value is undefined}}
  47   i = -1 << 0; // cxx17-warning {{shifting a negative signed value is undefined}}
  48   i = 0 << (WORD_BIT - 1);
  49   i = (char)1 << (WORD_BIT - 2);
  50
  51   unsigned u;
  52   u = 1U << (WORD_BIT - 1);
  53   u = 5U << (WORD_BIT - 1);
  54
  55   long long int lli;
  56   lli = INT_MIN << 2; // cxx17-warning {{shifting a negative signed value is undefined}}
  57   lli = 1LL << (sizeof(long long) * CHAR_BIT - 2);
  58 }
  59
  60 #define a 0
  61 #define ashift 8
  62 enum { b = (a << ashift) };
  63
  64 // Don't warn for negative shifts in code that is unreachable.
  65 void test_pr5544() {
  66   (void) (((1) > 63 && (1) < 128 ? (((unsigned long long) 1)<<((1)-64)) : (unsigned long long) 0)); // no-warning
  67 }
  68
  69 void test_shift_too_much(char x) {
  70   if (0)
  71     (void) (x >> 80); // no-warning
  72   (void) (x >> 80); // expected-warning {{shift count >= width of type}}
  73 }
  74
  75 typedef unsigned vec16 __attribute__((vector_size(16)));
  76 typedef unsigned vec8 __attribute__((vector_size(8)));
  77
  78 void vect_shift_1(vec16 *x) { *x = *x << 4; }
  79
  80 void vect_shift_2(vec16 *x, vec16 y) { *x = *x << y; }
  81
  82 void vect_shift_3(vec16 *x, vec8 y) {
  83   *x = *x << y; // expected-error {{vector operands do not have the same number of elements}}
  84 }