(automake-1.16.info)Options generalities

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17.1 Options generalities
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Various features of Automake can be controlled by options.  Except where
noted otherwise, options can be specified in one of several ways.  Most
options can be applied on a per-‘Makefile’ basis when listed in a
special ‘Makefile’ variable named ‘AUTOMAKE_OPTIONS’.  Some of these
options only make sense when specified in the toplevel ‘Makefile.am’
file.  Options are applied globally to all processed ‘Makefile’ files
when listed in the first argument of ‘AM_INIT_AUTOMAKE’ in
‘configure.ac’, and some options which require changes to the
‘configure’ script can only be specified there.  These are annotated
below.

   As a general rule, options specified in ‘AUTOMAKE_OPTIONS’ take
precedence over those specified in ‘AM_INIT_AUTOMAKE’, which in turn
take precedence over those specified on the command line.

   Also, some care must be taken about the interactions among strictness
level and warning categories.  As a general rule, strictness-implied
warnings are overridden by those specified by explicit options.  For
example, even if ‘portability’ warnings are disabled by default in
‘foreign’ strictness, an usage like this will end up enabling them:

     AUTOMAKE_OPTIONS = -Wportability foreign

   However, a strictness level specified in a higher-priority context
will override all the explicit warnings specified in a lower-priority
context.  For example, if ‘configure.ac’ contains:

     AM_INIT_AUTOMAKE([-Wportability])

and ‘Makefile.am’ contains:

     AUTOMAKE_OPTIONS = foreign

then ‘portability’ warnings will be _disabled_ in ‘Makefile.am’.