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| author | Paul Eggert <eggert@cs.ucla.edu> | 2016-02-22 23:07:02 -0800 |
|---|---|---|
| committer | Paul Eggert <eggert@cs.ucla.edu> | 2016-02-22 23:07:29 -0800 |
| commit | 19fc364cf851d95d7549b81189287f8ed846e51d (patch) | |
| tree | 2f141a9b877bc086cd134651d24fc24dd9b85cb7 | |
| parent | 04be2b7a29d65d9a08e64e8e56e594c91749598c (diff) | |
| download | autoconf-19fc364cf851d95d7549b81189287f8ed846e51d.tar.gz | |
AC_C_RESTRICT: port better to non-GCC + glibc
Problem reported by Dwight Guth in:
http://lists.gnu.org/archive/html/bug-autoconf/2016-02/msg00006.html
* lib/autoconf/c.m4 (AC_C_RESTRICT): Prefer __restrict__ to __restrict.
Also, fix and update some comments.
| -rw-r--r-- | lib/autoconf/c.m4 | 16 |
1 files changed, 9 insertions, 7 deletions
diff --git a/lib/autoconf/c.m4 b/lib/autoconf/c.m4 index 5b25c623..fe87dbfa 100644 --- a/lib/autoconf/c.m4 +++ b/lib/autoconf/c.m4 @@ -1855,8 +1855,10 @@ AN_IDENTIFIER([restrict], [AC_C_RESTRICT]) AC_DEFUN([AC_C_RESTRICT], [AC_CACHE_CHECK([for C/C++ restrict keyword], [ac_cv_c_restrict], [ac_cv_c_restrict=no - # The order here caters to the fact that C++ does not require restrict. - for ac_kw in __restrict __restrict__ _Restrict restrict; do + # Put '__restrict__' first, to avoid problems with glibc and non-GCC; see: + # http://lists.gnu.org/archive/html/bug-autoconf/2016-02/msg00006.html + # Put 'restrict' last, because C++ lacks it. + for ac_kw in __restrict__ __restrict _Restrict restrict; do AC_COMPILE_IFELSE( [AC_LANG_PROGRAM( [[typedef int *int_ptr; @@ -1876,13 +1878,13 @@ AC_DEFUN([AC_C_RESTRICT], AH_VERBATIM([restrict], [/* Define to the equivalent of the C99 'restrict' keyword, or to nothing if this is not supported. Do not define if restrict is - supported directly. */ + supported only directly. */ #undef restrict -/* Work around a bug in Sun C++: it does not support _Restrict or +/* Work around a bug in Sun C++ 5.13: it does not support _Restrict or __restrict__, even though the corresponding Sun C compiler ends up with - "#define restrict _Restrict" or "#define restrict __restrict__" in the - previous line. Perhaps some future version of Sun C++ will work with - restrict; if so, hopefully it defines __RESTRICT like Sun C does. */ + "#define restrict _Restrict" or "#define restrict __restrict__". + Perhaps some future version of Sun C++ will work with restrict; + if so, hopefully it defines __RESTRICT like Sun C does. */ #if defined __SUNPRO_CC && !defined __RESTRICT # define _Restrict # define __restrict__ |