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.
f(int array[restrict])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
45