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Diffstat (limited to 'm4/restrict.m4')
| -rw-r--r-- | m4/restrict.m4 | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/m4/restrict.m4 b/m4/restrict.m4 new file mode 100644 index 00000000..1f3bbb92 --- /dev/null +++ b/m4/restrict.m4 @@ -0,0 +1,38 @@ +#serial 1003 +dnl Copyright (C) 2003 Free Software Foundation, Inc. +dnl This file is free software; the Free Software Foundation +dnl gives unlimited permission to copy and/or distribute it, +dnl with or without modifications, as long as this notice is preserved. + +# This macro can be removed once we can rely on Autoconf 2.57a or later, +# since we can then use its AC_C_RESTRICT. + +# gl_C_RESTRICT +# -------------- +# Determine whether the C/C++ compiler supports the "restrict" keyword +# introduced in ANSI C99, or an equivalent. Do nothing if the compiler +# accepts it. Otherwise, if the compiler supports an equivalent, +# define "restrict" to be that. Here are some variants: +# - GCC supports both __restrict and __restrict__ +# - older DEC Alpha C compilers support only __restrict +# - _Restrict is the only spelling accepted by Sun WorkShop 6 update 2 C +# Otherwise, define "restrict" to be empty. +AC_DEFUN([gl_C_RESTRICT], +[AC_CACHE_CHECK([for C/C++ restrict keyword], gl_cv_c_restrict, + [gl_cv_c_restrict=no + # Try the official restrict keyword, then gcc's __restrict, and + # the less common variants. + for ac_kw in restrict __restrict __restrict__ _Restrict; do + AC_COMPILE_IFELSE([AC_LANG_SOURCE( + [float * $ac_kw x;])], + [gl_cv_c_restrict=$ac_kw; break]) + done + ]) + case $gl_cv_c_restrict in + restrict) ;; + no) AC_DEFINE(restrict,, + [Define to equivalent of C99 restrict keyword, or to nothing if this + is not supported. Do not define if restrict is supported directly.]) ;; + *) AC_DEFINE_UNQUOTED(restrict, $gl_cv_c_restrict) ;; + esac +]) |