Next: One-Shot Macros Prev: Prerequisite Macros Up: Dependencies Between Macros
9.4.2 Suggested Ordering
Some macros should be run before another macro if both are called, but
neither _requires_ that the other be called. For example, a macro that
changes the behavior of the C compiler should be called before any
macros that run the C compiler. Many of these dependencies are noted in
Autoconf provides the `AC_BEFORE' macro to warn users when macros
with this kind of dependency appear out of order in a `configure.ac'
file. The warning occurs when creating `configure' from
`configure.ac', not when running `configure'.
For example, `AC_PROG_CPP' checks whether the C compiler can run the
C preprocessor when given the `-E' option. It should therefore be
called after any macros that change which C compiler is being used,
such as `AC_PROG_CC'. So `AC_PROG_CC' contains:
This warns the user if a call to `AC_PROG_CPP' has already occurred
when `AC_PROG_CC' is called.
-- Macro: AC_BEFORE (THIS-MACRO-NAME, CALLED-MACRO-NAME)
Make M4 print a warning message to the standard error output if
CALLED-MACRO-NAME has already been called. THIS-MACRO-NAME should
be the name of the macro that is calling `AC_BEFORE'. The macro
CALLED-MACRO-NAME must have been defined using `AC_DEFUN' or else
contain a call to `AC_PROVIDE' to indicate that it has been called.
automatically generated by info2www