clang/test/C/C2x/n2900_n3011.c

   1 // RUN: %clang_cc1 -std=c2x -fsyntax-only -Wpre-c2x-compat -verify=compat %s
   2 // RUN: %clang_cc1 -std=c17 -fsyntax-only -pedantic -Wno-comment -verify=pedantic %s
   3
   4 /* WG14 N2900: yes
   5  * Consistent, Warningless, and Intuitive Initialization with {}
   6  */
   7
   8 /* WG14 N3011: yes
   9  * Consistent, Warningless, and Intuitive Initialization with {}
  10  */
  11 void test(void) {
  12   struct S { int x, y; } s = {}; // compat-warning {{use of an empty initializer is incompatible with C standards before C23}} \
  13                                     pedantic-warning {{use of an empty initializer is a C23 extension}}
  14   int i = {}; // compat-warning {{use of an empty initializer is incompatible with C standards before C23}} \
  15                                   pedantic-warning {{use of an empty initializer is a C23 extension}}
  16   int j = (int){}; // compat-warning {{use of an empty initializer is incompatible with C standards before C23}} \
  17                       pedantic-warning {{use of an empty initializer is a C23 extension}}
  18
  19   // C2x 6.7.10p4 says, in part: An array of unknown size shall not be
  20   // initialized by an empty initializer.
  21   // However, Clang allows zero-sized arrays as an extension in both C and C++,
  22   // and this initialization form will deduce the array extent as zero. Given
  23   // that we support empty initialization of an unbounded array in C++, we also
  24   // support it in C.
  25   int unknown_size[] = {}; // pedantic-warning {{zero size arrays are an extension}} \
  26                               pedantic-warning {{use of an empty initializer is a C23 extension}} \
  27                               compat-warning {{use of an empty initializer is incompatible with C standards before C23}}
  28   int vla[i] = {}; // compat-warning {{use of an empty initializer is incompatible with C standards before C23}} \
  29                       pedantic-warning {{use of an empty initializer is a C23 extension}}
  30   int *compound_literal_vla = (int[i]){}; // compat-warning {{use of an empty initializer is incompatible with C standards before C23}} \
  31                                              pedantic-warning {{use of an empty initializer is a C23 extension}}
  32
  33   struct T {
  34         int i;
  35     struct S s;
  36   } t1 = { 1, {} }; // compat-warning {{use of an empty initializer is incompatible with C standards before C23}} \
  37                        pedantic-warning {{use of an empty initializer is a C23 extension}}
  38
  39   struct T t2 = {
  40     1, {
  41       2, {} // compat-warning {{use of an empty initializer is incompatible with C standards before C23}} \
  42                pedantic-warning {{use of an empty initializer is a C23 extension}}
  43     }
  44   };
  45
  46   struct T t3 = {
  47     (int){}, // compat-warning {{use of an empty initializer is incompatible with C standards before C23}} \
  48                 pedantic-warning {{use of an empty initializer is a C23 extension}}
  49     {} // compat-warning {{use of an empty initializer is incompatible with C standards before C23}} \
  50           pedantic-warning {{use of an empty initializer is a C23 extension}}
  51   };
  52
  53   // Ensure that zero initialization does what you'd expect in a constant expr.
  54   // FIXME: the "not an ICE" warning is incorrect for C2x, but we don't yet
  55   // implement WG14 N3038.
  56   _Static_assert((int){} == 0, "what?");  // compat-warning {{use of an empty initializer is incompatible with C standards before C23}} \
  57                                              pedantic-warning {{use of an empty initializer is a C23 extension}} \
  58                                              pedantic-warning {{expression is not an integer constant expression; folding it to a constant is a GNU extension}}
  59 }
  60