(ACX_C_RESTRICT): Remove #ifndef -- so now this

macro also checks for support when using a C++ compiler.
Also, remove the test for SGI's __restrict.
Suggested by Steven G. Johnson.

1 files changed, 11 insertions, 16 deletions

diff --git a/m4/restrict.m4 b/m4/restrict.m4
index 902dc1308..ca4f70f0b 100644
--- a/m4/restrict.m4
+++ b/m4/restrict.m4
@@ -1,26 +1,21 @@
-#serial 1000
+#serial 1001
 dnl based on acx_restrict.m4, from the GNU Autoconf Macro Archive at:
 dnl http://www.gnu.org/software/ac-archive/htmldoc/acx_restrict.html
 
-# Determine whether the 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 (like gcc's __restrict__)
-# define "restrict" to be that.  Otherwise, define "restrict" to be empty.
+# 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 (like
+# gcc's __restrict__) define "restrict" to be that.  Otherwise, define
+# "restrict" to be empty.
 
 AC_DEFUN([ACX_C_RESTRICT],
-[AC_CACHE_CHECK([for C restrict keyword], acx_cv_c_restrict,
+[AC_CACHE_CHECK([for C/C++ restrict keyword], acx_cv_c_restrict,
   [acx_cv_c_restrict=no
-   # Try the official restrict keyword, then gcc's __restrict__, then
-   # SGI's __restrict.  __restrict has slightly different semantics than
-   # restrict (it's a bit stronger, in that __restrict pointers can't
-   # overlap even with non __restrict pointers), but I think it should be
-   # okay under the circumstances where restrict is normally used.
-   for acx_kw in restrict __restrict__ __restrict; do
+   # Try the official restrict keyword, then gcc's __restrict__.
+   for acx_kw in restrict __restrict__; do
      AC_COMPILE_IFELSE([AC_LANG_SOURCE(
-      [#ifndef __cplusplus
-      float * $acx_kw x;
-#endif
-      ])], [acx_cv_c_restrict=$acx_kw; break])
+      [float * $acx_kw x;])],
+      [acx_cv_c_restrict=$acx_kw; break])
    done
   ])
  case $acx_cv_c_restrict in