[Retaining the CC: to 357369-forwarded@xxxxxxxxxxxxxxx will make for easier tracking of the bug report at Debian.] Consider the following configure.ac: ---------------------------------------------------------------------- AC_PREREQ(2.50) AC_INIT(test, 1.0) AC_PROG_CC AC_PROG_CXX AC_OUTPUT ---------------------------------------------------------------------- If I invoke the generated ./configure in the following way, it fails very quickly because "nonexistent" is not a program: CC=nonexistent ./configure Here is the output: checking for gcc... nonexistent checking for C compiler default output file name... configure: error: C compiler cannot create executables See `config.log' for more details. On the other hand, if I invoke it this way, it completely succeeds: CXX=nonexistent ./configure Here is the output: checking for gcc... gcc checking for C compiler default output file name... a.out checking whether the C compiler works... yes checking whether we are cross compiling... no checking for suffix of executables... checking for suffix of object files... o checking whether we are using the GNU C compiler... yes checking whether gcc accepts -g... yes checking for gcc option to accept ANSI C... none needed checking whether we are using the GNU C++ compiler... no checking whether nonexistent accepts -g... no configure: creating ./config.status The situation is reversed if the AC_PROG_CC and AC_PROG_CXX lines are correspondingly reversed in the configure.ac. The reason, as far as I can tell, is this line in AC_PROG_CC and AC_PROG_CXX: m4_expand_once([_AC_COMPILER_EXEEXT])[]dnl _AC_COMPILER_EXEEXT is what checks that the compiler really exists and works, but it only gets run once per configure script, not once per compiler. I've tested this with Debian's Autoconf 2.59. I don't think the situation has changed in CVS, based on a brief look at the source, but I haven't actually tested it. -- Ben Pfaff email: blp@xxxxxxxxxxxxxxx web: http://benpfaff.org _______________________________________________ Autoconf mailing list Autoconf@xxxxxxx http://lists.gnu.org/mailman/listinfo/autoconf