clang/test/C/C99/n448.c

   1 // RUN: %clang_cc1 -verify -std=c99 %s
   2 // RUN: %clang_cc1 -verify -std=c23 %s
   3
   4 /* WG14 N448: Partial
   5  * Restricted pointers
   6  *
   7  * NB: we claim partial conformance only because LLVM does not attempt to apply
   8  * the semantics on local variables or structure data members; it only
   9  * considers function parameters. However, Clang itself is fully conforming for
  10  * this feature.
  11  */
  12
  13 // Restrict is only allowed on pointers.
  14 int * restrict ipr;
  15 int restrict ir; // expected-error {{restrict requires a pointer or reference ('int' is invalid)}}
  16
  17 // Restrict only applies to object pointers.
  18 void (* restrict fp)(void); // expected-error {{pointer to function type 'void (void)' may not be 'restrict' qualified}}
  19
  20 typedef int *int_ptr;
  21 int_ptr restrict ipr2; // okay, still applied to the pointer.
  22
  23 // Show that the qualifer is dropped on lvalue conversion
  24 _Static_assert(
  25   _Generic(ipr,
  26     int * : 1,
  27     int * restrict : 0, // expected-warning {{due to lvalue conversion of the controlling expression, association of type 'int *restrict' will never be selected because it is qualified}}
  28     default : 0),
  29   "");
  30
  31 // Show that it's allowed as a qualifier for array parameters.
  32 void f(int array[restrict]) {
  33   int *ipnr = ipr; // okay to drop the top-level qualifier
  34
  35   // Show that it's not okay to drop the qualifier when it's not at the top level.
  36   int * restrict * restrict iprpr;
  37   int **ipp = iprpr;            // expected-warning {{initializing 'int **' with an expression of type 'int *restrict *restrict' discards qualifiers}}
  38   int ** restrict ippr = iprpr; // expected-warning {{initializing 'int **restrict' with an expression of type 'int *restrict *restrict' discards qualifiers}}
  39 }
  40
  41 #if __STDC_VERSION__ >= 202311L
  42 // C23 doesn't allow constexpr to mix with restrict. See C23 6.7.2p5.
  43 constexpr int * restrict ip; // expected-error {{constexpr variable cannot have type 'int *const restrict'}}
  44 #endif // __STDC_VERSION__ >= 202311L