clang/test/Sema/constant-conversion.c

   1 // RUN: %clang_cc1 -fsyntax-only -verify -triple x86_64-apple-darwin %s
   2
   3 // This file tests -Wconstant-conversion, a subcategory of -Wconversion
   4 // which is on by default.
   5
   6 // rdar://problem/6792488
   7 void test_6792488(void) {
   8   int x = 0x3ff0000000000000U; // expected-warning {{implicit conversion from 'unsigned long' to 'int' changes value from 4607182418800017408 to 0}}
   9 }
  10
  11 void test_7809123(void) {
  12   struct { int i5 : 5; } a;
  13
  14   a.i5 = 36; // expected-warning {{implicit truncation from 'int' to bit-field changes value from 36 to 4}}
  15 }
  16
  17 void test(void) {
  18   struct { int bit : 1; } a;
  19   a.bit = 1; // shouldn't warn
  20 }
  21
  22 enum Test2 { K_zero, K_one };
  23 enum Test2 test2(enum Test2 *t) {
  24   *t = 20;
  25   return 10; // shouldn't warn
  26 }
  27
  28 void test3(void) {
  29   struct A {
  30     unsigned int foo : 2;
  31     int bar : 2;
  32   };
  33
  34   struct A a = { 0, 10 };            // expected-warning {{implicit truncation from 'int' to bit-field changes value from 10 to -2}}
  35   struct A b[] = { 0, 10, 0, 0 };    // expected-warning {{implicit truncation from 'int' to bit-field changes value from 10 to -2}}
  36   struct A c[] = {{10, 0}};          // expected-warning {{implicit truncation from 'int' to bit-field changes value from 10 to 2}}
  37   struct A d = (struct A) { 10, 0 }; // expected-warning {{implicit truncation from 'int' to bit-field changes value from 10 to 2}}
  38   struct A e = { .foo = 10 };        // expected-warning {{implicit truncation from 'int' to bit-field changes value from 10 to 2}}
  39 }
  40
  41 void test4(void) {
  42   struct A {
  43     char c : 2;
  44   } a;
  45
  46   a.c = 0x101; // expected-warning {{implicit truncation from 'int' to bit-field changes value from 257 to 1}}
  47 }
  48
  49 void test5(void) {
  50   struct A {
  51     _Bool b : 1;
  52   } a;
  53
  54   // Don't warn about this implicit conversion to bool, or at least
  55   // don't warn about it just because it's a bit-field.
  56   a.b = 100;
  57 }
  58
  59 void test6(void) {
  60   // Test that unreachable code doesn't trigger the truncation warning.
  61   unsigned char x = 0 ? 65535 : 1; // no-warning
  62   unsigned char y = 1 ? 65535 : 1; // expected-warning {{changes value}}
  63 }
  64
  65 void test7(void) {
  66         struct {
  67                 unsigned int twoBits1:2;
  68                 unsigned int twoBits2:2;
  69                 unsigned int reserved:28;
  70         } f;
  71
  72         f.twoBits1 = ~0; // no-warning
  73         f.twoBits1 = ~1; // no-warning
  74         f.twoBits2 = ~2; // expected-warning {{implicit truncation from 'int' to bit-field changes value from -3 to 1}}
  75         f.twoBits1 &= ~1; // no-warning
  76         f.twoBits2 &= ~2; // no-warning
  77 }
  78
  79 void test8(void) {
  80   enum E { A, B, C };
  81   struct { enum E x : 1; } f;
  82   f.x = C; // expected-warning {{implicit truncation from 'int' to bit-field changes value from 2 to 0}}
  83 }
  84
  85 void test9(void) {
  86   const char max_char = 0x7F;
  87   const short max_short = 0x7FFF;
  88   const int max_int = 0x7FFFFFFF;
  89
  90   const short max_char_plus_one = (short)max_char + 1;
  91   const int max_short_plus_one = (int)max_short + 1;
  92   const long max_int_plus_one = (long)max_int + 1;
  93
  94   char new_char = max_char_plus_one;  // expected-warning {{implicit conversion from 'const short' to 'char' changes value from 128 to -128}}
  95   short new_short = max_short_plus_one;  // expected-warning {{implicit conversion from 'const int' to 'short' changes value from 32768 to -32768}}
  96   int new_int = max_int_plus_one;  // expected-warning {{implicit conversion from 'const long' to 'int' changes value from 2147483648 to -2147483648}}
  97
  98   char hex_char = 0x80;
  99   short hex_short = 0x8000;
 100   int hex_int = 0x80000000;
 101
 102   char oct_char = 0200;
 103   short oct_short = 0100000;
 104   int oct_int = 020000000000;
 105
 106   char bin_char = 0b10000000;
 107   short bin_short = 0b1000000000000000;
 108   int bin_int = 0b10000000000000000000000000000000;
 109
 110 #define CHAR_MACRO_HEX 0xff
 111   char macro_char_hex = CHAR_MACRO_HEX;
 112 #define CHAR_MACRO_DEC 255
 113   char macro_char_dec = CHAR_MACRO_DEC;  // expected-warning {{implicit conversion from 'int' to 'char' changes value from 255 to -1}}
 114
 115   char array_init[] = { 255, 127, 128, 129, 0 };
 116 }
 117
 118 #define A 1
 119
 120 void test10(void) {
 121   struct S {
 122     unsigned a : 4;
 123   } s;
 124   s.a = -1;
 125   s.a = 15;
 126   s.a = -8;
 127   s.a = ~0;
 128   s.a = ~0U;
 129   s.a = ~(1<<A);
 130
 131   s.a = -9;  // expected-warning{{implicit truncation from 'int' to bit-field changes value from -9 to 7}}
 132   s.a = 16;  // expected-warning{{implicit truncation from 'int' to bit-field changes value from 16 to 0}}
 133 }