clang/test/Sema/warn-cast-align.c

   1 // RUN: %clang_cc1 -triple x86_64-apple-darwin10 -fsyntax-only -Wcast-align -verify %s
   2
   3 // Simple casts.
   4 void test0(char *P) {
   5   char *a  = (char*)  P;
   6   short *b = (short*) P; // expected-warning {{cast from 'char *' to 'short *' increases required alignment from 1 to 2}}
   7   int *c   = (int*)   P; // expected-warning {{cast from 'char *' to 'int *' increases required alignment from 1 to 4}}
   8 }
   9
  10 // Casts from void* are a special case.
  11 void test1(void *P) {
  12   char *a  = (char*)  P;
  13   short *b = (short*) P;
  14   int *c   = (int*)   P;
  15
  16   const volatile void *P2 = P;
  17   char *d  = (char*)  P2;
  18   short *e = (short*) P2;
  19   int *f   = (int*)   P2;
  20
  21   const char *g  = (const char*)  P2;
  22   const short *h = (const short*) P2;
  23   const int *i   = (const int*)   P2;
  24
  25   const volatile char *j  = (const volatile char*)  P2;
  26   const volatile short *k = (const volatile short*) P2;
  27   const volatile int *l   = (const volatile int*)   P2;
  28 }
  29
  30 // Aligned struct.
  31 struct __attribute__((aligned(16))) A {
  32   char buffer[16];
  33 };
  34 void test2(char *P) {
  35   struct A *a = (struct A*) P; // expected-warning {{cast from 'char *' to 'struct A *' increases required alignment from 1 to 16}}
  36 }
  37
  38 // Incomplete type.
  39 void test3(char *P) {
  40   struct B *b = (struct B*) P;
  41 }
  42
  43 // Do not issue a warning. The aligned attribute changes the alignment of the
  44 // variables and fields.
  45 char __attribute__((aligned(4))) a[16];
  46
  47 struct S0 {
  48   char a[16];
  49 };
  50
  51 struct S {
  52   char __attribute__((aligned(4))) a[16];
  53   struct S0 __attribute__((aligned(4))) s0;
  54 };
  55
  56 void test4(void) {
  57   struct S s;
  58   int *i = (int *)s.a;
  59   i = (int *)&s.s0;
  60   i = (int *)a;
  61 }
  62
  63 // No warnings.
  64 typedef int (*FnTy)(void);
  65 unsigned int func5(void);
  66
  67 FnTy test5(void) {
  68   return (FnTy)&func5;
  69 }
  70
  71 void test6(void) {
  72   struct {
  73     int hello;
  74     doesnotexist world; // expected-error {{unknown type name 'doesnotexist'}}
  75   } foo;
  76   void **repro = (void **)&foo.hello; // expected-warning {{cast from 'int *' to 'void **' increases required alignment from 4 to 8}}
  77 }