I think it might be a good idea if AC_PROG_CC_C99 used "c99" in preference to other command names ("cc") for the name of the C compiler. POSIX requires this command to be available: http://pubs.opengroup.org/onlinepubs/9699919799/utilities/c99.html#tag_20_11 Why do I make this suggestion? It's due to a problem I had compiling a program under OpenIndiana 11. The configure script found "cc" as the compiler, and it passed the checks for C99 features. However, the source code had #define _XOPEN_SOURCE 600 before including system headers, and this led to an error message: #error: "Compiler or options invalid; UNIX 03 and POSIX.1-2001 applications require the use of c99" The system headers refuse to allow the program to compile, even though it would in all likelihood be fine. I wondered who was to blame for being nonconformant to standards: OpenIndiana, or the autoconf script? OpenIndiana did have a C99 compiler and POSIX headers, but the right compiler just wasn't used. I can't see any argument to say that OpenIndiana is the problem here. If autoconf had tried for the C compiler under the standardized name first, there wouldn't have been a problem. _______________________________________________ Autoconf mailing list Autoconf@xxxxxxx https://lists.gnu.org/mailman/listinfo/autoconf