| @node configmake | |
| @section configmake | |
| @mindex configmake | |
| @cindex @file{configmake.h}, module for updating | |
| The @code{configmake} module builds a C include file named | |
| @file{configmake.h} containing the usual installation directory | |
| values; for example, those specified by @code{--prefix} or | |
| @code{--libdir} to configure. Each variable is given a @code{#define} | |
| with an all-uppercase macro name, such as @code{PREFIX} and | |
| @code{LIBDIR}. (Automake cannot create this file directly because the | |
| user might override directory values at @code{make} time.) | |
| Specifically, the module retrieves values of the variables through | |
| @code{configure} followed by @code{make}, not directly through | |
| @code{configure}, so that a user who sets some of these variables | |
| consistently on the @code{make} command line gets correct results. | |
| One advantage of this approach, compared to the classical approach of | |
| adding @code{-DLIBDIR=\"$(libdir)\"} etc.@: to @code{AM_CPPFLAGS}, is | |
| that it protects against the use of undefined variables. That is, if, | |
| say, @code{$(libdir)} is not set in the Makefile, @code{LIBDIR} is not | |
| defined by this module, and code using @code{LIBDIR} gives a | |
| compilation error. | |
| Another advantage is that @code{make} output is shorter. | |
| For the complete list of variables which are @code{#define}d this way, | |
| see the file @file{gnulib/modules/configmake}, or inspect your | |
| resulting gnulib Makefile. |