constant-conversion.c revision 25ffbef84450f0c666957a2d00cdf928c61b44d7 
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
7void test_6792488(void) {
8  int x = 0x3ff0000000000000U; // expected-warning {{implicit conversion from 'unsigned long' to 'int' changes value from 4607182418800017408 to 0}}
9}
10
11void test_7809123(void) {
12  struct { int i5 : 5; } a;
13
14  a.i5 = 36; // expected-warning {{implicit truncation from 'int' to bitfield changes value from 36 to 4}}
15}
16
17void test() {
18  struct { int bit : 1; } a;
19  a.bit = 1; // shouldn't warn
20}
21
22enum Test2 { K_zero, K_one };
23enum Test2 test2(enum Test2 *t) {
24  *t = 20;
25  return 10; // shouldn't warn
26}
27
28void test3() {
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 bitfield changes value from 10 to -2}}
35  struct A b[] = { 0, 10, 0, 0 };    // expected-warning {{implicit truncation from 'int' to bitfield changes value from 10 to -2}}
36  struct A c[] = {{10, 0}};          // expected-warning {{implicit truncation from 'int' to bitfield changes value from 10 to 2}}
37  struct A d = (struct A) { 10, 0 }; // expected-warning {{implicit truncation from 'int' to bitfield changes value from 10 to 2}}
38  struct A e = { .foo = 10 };        // expected-warning {{implicit truncation from 'int' to bitfield changes value from 10 to 2}}
39}
40
41void test4() {
42  struct A {
43    char c : 2;
44  } a;
45
46  a.c = 0x101; // expected-warning {{implicit truncation from 'int' to bitfield changes value from 257 to 1}}
47}
48
49void test5() {
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 bitfield.
56  a.b = 100;
57}
58
59void test6() {
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
65void test7() {
66	struct {
67		unsigned int twoBits1:2;
68		unsigned int twoBits2:2;
69		unsigned int twoBits3:2;
70		unsigned int reserved:26;
71	} f;
72
73	f.twoBits1 = ~1; // expected-warning {{implicit truncation from 'int' to bitfield changes value from -2 to 2}}
74	f.twoBits2 = ~2; // expected-warning {{implicit truncation from 'int' to bitfield changes value from -3 to 1}}
75	f.twoBits1 &= ~1; // no-warning
76	f.twoBits2 &= ~2; // no-warning
77	f.twoBits3 |= 4; // expected-warning {{implicit truncation from 'int' to bitfield changes value from 4 to 0}}
78	f.twoBits3 += 4; // expected-warning {{implicit truncation from 'int' to bitfield changes value from 4 to 0}}
79	f.twoBits3 *= 4; // expected-warning {{implicit truncation from 'int' to bitfield changes value from 4 to 0}}
80	f.twoBits3 |= 1; // no-warning
81}
82
83void test8() {
84  enum E { A, B, C };
85  struct { enum E x : 1; } f;
86  f.x = C; // expected-warning {{implicit truncation from 'int' to bitfield changes value from 2 to 0}}
87}
88
89int func(int);
90
91void test9() {
92  unsigned char x = 0;
93  unsigned char y = 0;
94  x = y | 0x1ff; // expected-warning {{implicit conversion of binary operation from 'int' to 'unsigned char' may change its value; value of operand would be changed from 511 to 255 if converted before operation}}
95  x = y | 0xff; // no-warning
96  x = y & 0xdff; // expected-warning {{implicit conversion of binary operation from 'int' to 'unsigned char' may change its value; value of operand would be changed from 3583 to 255 if converted before operation}}
97  x = y & 0xff; // no-warning
98  x = y & ~1; // no-warning
99  x = 0x1ff | y; // expected-warning {{implicit conversion of binary operation from 'int' to 'unsigned char' may change its value; value of operand would be changed from 511 to 255 if converted before operation}}
100  x = 0xff | y; // no-warning
101  x = (y | 0x1ff); // expected-warning {{implicit conversion of binary operation from 'int' to 'unsigned char' may change its value; value of operand would be changed from 511 to 255 if converted before operation}}
102  x = (y | 0xff); // no-warning
103  x = 0xff + y; // no-warning
104  x += 0x1ff; // expected-warning {{implicit conversion from 'int' to 'unsigned char' changes value from 511 to 255}}
105  x = 0xff - y; // no-warning
106  x -= 0x1ff; // expected-warning {{implicit conversion from 'int' to 'unsigned char' changes value from 511 to 255}}
107  x = y * 0x1ff; // expected-warning {{implicit conversion of binary operation from 'int' to 'unsigned char' may change its value; value of operand would be changed from 511 to 255 if converted before operation}}
108  x = y * 0xff; // no-warning
109  x *= 0x1ff; // expected-warning {{implicit conversion from 'int' to 'unsigned char' changes value from 511 to 255}}
110  x = y ^ 0xff; // no-warning
111  x ^= 0x1ff; // expected-warning {{implicit conversion from 'int' to 'unsigned char' changes value from 511 to 255}}
112  x = (func(1), 0x1ff); // expected-warning {{implicit conversion of binary operation from 'int' to 'unsigned char' may change its value; value of operand would be changed from 511 to 255 if converted before operation}}
113  x = (func(1), 0xff); // no-warning
114  x = 0xff << y; // no-warning
115  x = 0x1ff << y; // expected-warning {{implicit conversion of binary operation from 'int' to 'unsigned char' may change its value; value of operand would be changed from 511 to 255 if converted before operation}}
116
117
118  // These next two tests make sure that both LHS and RHS are checked for
119  // narrowing operations.
120  x = 0x1ff | 0xff; // expected-warning {{implicit conversion of binary operation from 'int' to 'unsigned char' may change its value; value of operand would be changed from 511 to 255 if converted before operation}}
121  x = 0xff | 0x1ff; // expected-warning {{implicit conversion of binary operation from 'int' to 'unsigned char' may change its value; value of operand would be changed from 511 to 255 if converted before operation}}
122}
123