--with-*-cflags?

[Ilya N. Golubev]

Is

AC_ARG_WITH([cflags-warning],
dnl ...
)

a proper usage of `AC_ARG_WITH'?  Or it violates autoconf conventions,
and some other ways of specifying these configuration options
(perhaps, `var=value' in command line) are more appropriate?

Know at least one package doing so.  Specifying parts of cflags to be
eventually combined may be really useful.  Depending on build / host
systems or configuration options, some user specified values may be
overridden, or perhaps some flags added to them.  And all that done
surely on warning or optimization flags, with the results being
combined into address@hidden@' substitution only eventually.

On one hand, there is no such `cflags-warning' software package that
may be installed or not installed on a system.  On the other hand,
useful values of these options obviously depend on compiler, that is
obviously external software wrt package being configured.  Moreover,
the set of possible options may theoretically depend on some compiler
add-ons being installed (however, never have heard of such add-ons to
any compiler to date).