There is no mention of a
Most simply by putting
configure.ac (in addition to
configure.ac is a template for a shell script, so you can simply put shell code in it. In fact, all the
AC_FOO_BAR m4 macros expand to shell code themselves.
AX_CHECK_COMPILE_FLAG([-std=c11], [ CFLAGS+=" -std=c11" ], [ echo "C compiler cannot compile C11 code" exit -1 ])
...although simply waiting until something fails in the compilation also works, I suppose. The error message will be nicer this way, though.