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Diffstat (limited to 'gnulib/import/m4/vararrays.m4')
-rw-r--r-- | gnulib/import/m4/vararrays.m4 | 72 |
1 files changed, 72 insertions, 0 deletions
diff --git a/gnulib/import/m4/vararrays.m4 b/gnulib/import/m4/vararrays.m4 new file mode 100644 index 0000000..28e22a4 --- /dev/null +++ b/gnulib/import/m4/vararrays.m4 @@ -0,0 +1,72 @@ +# Check for variable-length arrays. + +# serial 6 + +# From Paul Eggert + +# Copyright (C) 2001, 2009-2022 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. + +m4_version_prereq([2.70], [], [ + +# AC_C_VARARRAYS +# -------------- +# Check whether the C compiler supports variable-length arrays. +AC_DEFUN([AC_C_VARARRAYS], +[ + AC_CACHE_CHECK([for variable-length arrays], + ac_cv_c_vararrays, + [AC_EGREP_CPP([defined], + [#ifdef __STDC_NO_VLA__ + defined + #endif + ], + [ac_cv_c_vararrays='no: __STDC_NO_VLA__ is defined'], + [AC_COMPILE_IFELSE( + [AC_LANG_PROGRAM( + [[/* Test for VLA support. This test is partly inspired + from examples in the C standard. Use at least two VLA + functions to detect the GCC 3.4.3 bug described in: + https://lists.gnu.org/archive/html/bug-gnulib/2014-08/msg00014.html + */ + #ifdef __STDC_NO_VLA__ + syntax error; + #else + extern int n; + int B[100]; + int fvla (int m, int C[m][m]); + + int + simple (int count, int all[static count]) + { + return all[count - 1]; + } + + int + fvla (int m, int C[m][m]) + { + typedef int VLA[m][m]; + VLA x; + int D[m]; + static int (*q)[m] = &B; + int (*s)[n] = q; + return C && &x[0][0] == &D[0] && &D[0] == s[0]; + } + #endif + ]])], + [ac_cv_c_vararrays=yes], + [ac_cv_c_vararrays=no])])]) + if test "$ac_cv_c_vararrays" = yes; then + dnl This is for compatibility with Autoconf 2.61-2.69. + AC_DEFINE([HAVE_C_VARARRAYS], 1, + [Define to 1 if C supports variable-length arrays.]) + elif test "$ac_cv_c_vararrays" = no; then + AC_DEFINE([__STDC_NO_VLA__], 1, + [Define to 1 if C does not support variable-length arrays, and + if the compiler does not already define this.]) + fi +]) + +]) |