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authorJörg Frings-Fürst <debian@jff-webhosting.net>2017-03-27 21:42:03 +0200
committerJörg Frings-Fürst <debian@jff-webhosting.net>2017-03-27 21:42:03 +0200
commitdb6f1f397f45ccd3c11d16352ed46a9c1eae3442 (patch)
treee0b9334e2637f17696c796ac13b2c39294bf9233 /gnulib-m4/flexmember.m4
parent0250cb64565a7d5238bbc751225d4b0236ef8316 (diff)
parent6b73edd95d603e27d55d4905134ac1327d426534 (diff)
Merge tag 'upstream/0.9.7'
Upstream version 0.9.7
Diffstat (limited to 'gnulib-m4/flexmember.m4')
-rw-r--r--gnulib-m4/flexmember.m443
1 files changed, 43 insertions, 0 deletions
diff --git a/gnulib-m4/flexmember.m4 b/gnulib-m4/flexmember.m4
new file mode 100644
index 00000000..155ae9b8
--- /dev/null
+++ b/gnulib-m4/flexmember.m4
@@ -0,0 +1,43 @@
+# serial 4
+# Check for flexible array member support.
+
+# Copyright (C) 2006, 2009-2016 Free Software Foundation, Inc.
+# This file is free software; the Free Software Foundation
+# gives unlimited permission to copy and/or distribute it,
+# with or without modifications, as long as this notice is preserved.
+
+# Written by Paul Eggert.
+
+AC_DEFUN([AC_C_FLEXIBLE_ARRAY_MEMBER],
+[
+ AC_CACHE_CHECK([for flexible array member],
+ ac_cv_c_flexmember,
+ [AC_COMPILE_IFELSE(
+ [AC_LANG_PROGRAM(
+ [[#include <stdlib.h>
+ #include <stdio.h>
+ #include <stddef.h>
+ struct s { int n; double d[]; };]],
+ [[int m = getchar ();
+ size_t nbytes = offsetof (struct s, d) + m * sizeof (double);
+ nbytes += sizeof (struct s) - 1;
+ nbytes -= nbytes % sizeof (struct s);
+ struct s *p = malloc (nbytes);
+ p->d[0] = 0.0;
+ return p->d != (double *) NULL;]])],
+ [ac_cv_c_flexmember=yes],
+ [ac_cv_c_flexmember=no])])
+ if test $ac_cv_c_flexmember = yes; then
+ AC_DEFINE([FLEXIBLE_ARRAY_MEMBER], [],
+ [Define to nothing if C supports flexible array members, and to
+ 1 if it does not. That way, with a declaration like 'struct s
+ { int n; double d@<:@FLEXIBLE_ARRAY_MEMBER@:>@; };', the struct hack
+ can be used with pre-C99 compilers.
+ When computing the size of such an object, don't use 'sizeof (struct s)'
+ as it overestimates the size. Use 'offsetof (struct s, d)' instead.
+ Don't use 'offsetof (struct s, d@<:@0@:>@)', as this doesn't work with
+ MSVC and with C++ compilers.])
+ else
+ AC_DEFINE([FLEXIBLE_ARRAY_MEMBER], [1])
+ fi
+])