1 # serial 5 2 # Check for flexible array member support. 3 4 # Copyright (C) 2006, 2009-2022 Free Software Foundation, Inc. 5 # This file is free software; the Free Software Foundation 6 # gives unlimited permission to copy and/or distribute it, 7 # with or without modifications, as long as this notice is preserved. 8 9 # Written by Paul Eggert. 10 11 AC_DEFUN([AC_C_FLEXIBLE_ARRAY_MEMBER], 12 [ 13 AC_CACHE_CHECK([for flexible array member], 14 ac_cv_c_flexmember, 15 [AC_COMPILE_IFELSE( 16 [AC_LANG_PROGRAM( 17 [[#include <stdlib.h> 18 #include <stdio.h> 19 #include <stddef.h> 20 struct m { struct m *next, **list; char name[]; }; 21 struct s { struct s *p; struct m *m; int n; double d[]; };]], 22 [[int m = getchar (); 23 size_t nbytes = offsetof (struct s, d) + m * sizeof (double); 24 nbytes += sizeof (struct s) - 1; 25 nbytes -= nbytes % sizeof (struct s); 26 struct s *p = malloc (nbytes); 27 p->p = p; 28 p->m = NULL; 29 p->d[0] = 0.0; 30 return p->d != (double *) NULL;]])], 31 [ac_cv_c_flexmember=yes], 32 [ac_cv_c_flexmember=no])]) 33 if test $ac_cv_c_flexmember = yes; then 34 AC_DEFINE([FLEXIBLE_ARRAY_MEMBER], [], 35 [Define to nothing if C supports flexible array members, and to 36 1 if it does not. That way, with a declaration like 'struct s 37 { int n; short d@<:@FLEXIBLE_ARRAY_MEMBER@:>@; };', the struct hack 38 can be used with pre-C99 compilers. 39 Use 'FLEXSIZEOF (struct s, d, N * sizeof (short))' to calculate 40 the size in bytes of such a struct containing an N-element array.]) 41 else 42 AC_DEFINE([FLEXIBLE_ARRAY_MEMBER], [1]) 43 fi 44 ]) 45
Indexes created Thu Apr 30 00:23:01 UTC 2026