how to use variables for strings in autoconf:configure.ac

Question

How to use variables for messages inside configure.ac

if test "$foo" = "yes"; then
    AC_MSG_ERROR([this string is being used in WARN as well as ERROR])
else
    AC_MSG_WARN([this string is being used in WARN as well as ERROR])
fi

It would make sense to define the string "this string is being used in WARN as well as ERROR" in a variable and then use that variable in both AC_MSG_WARN and AC_MSG_ERROR. What is the best way to do that ?

In addition to that, does m4 has any macro which can replace this entire if else by taking string and $foo as argument ?

Answer 1

This should work:

msg="this string is being used in WARN as well as ERROR"
if test "$foo" = "yes"; then
    AC_MSG_ERROR([$msg])
else
    AC_MSG_WARN([$msg])
fi

In addition to that, does m4 has any macro which can replace this entire if else by taking string and $foo as argument ?

If you write one, it will. :-). The if-else isn't in m4, it's in the output of m4, the configure shell script. Something like:

AC_DEFUN([AX_TEST_FOO], [
    pushdef([MSG],$1)
    pushdef([FOO],$2)
    AS_IF([test $FOO = yes], [AC_MSG_ERROR([$MSG])], [AC_MSG_WARN([$MSG])])
    popdef([FOO])
    popdef([MSG])
])

called like:

AX_TEST_FOO(["this string is being used in WARN as well as ERROR"], [$foo])

should be close. I didn't try it.