15.4 Configuring Other Packages in Subdirectories

In most situations, calling AC_OUTPUT is sufficient to produce makefiles in subdirectories. However, configure scripts that control more than one independent package can use AC_CONFIG_SUBDIRS to run configure scripts for other packages in subdirectories.

Macro: AC_CONFIG_SUBDIRS (dir …)

Make AC_OUTPUT run configure in each subdirectory dir in the given blank-or-newline-separated list. Each dir should be a literal, i.e., please do not use:

if test "x$package_foo_enabled" = xyes; then
  my_subdirs="$my_subdirs foo"
fi
AC_CONFIG_SUBDIRS([$my_subdirs])

because this prevents ‘./configure --help=recursive’ from displaying the options of the package foo. Instead, you should write:

if test "x$package_foo_enabled" = xyes; then
  AC_CONFIG_SUBDIRS([foo])
fi

If a given dir is not found at configure run time, a warning is reported; if the subdirectory is optional, write:

if test -d "$srcdir/foo"; then
  AC_CONFIG_SUBDIRS([foo])
fi

If a given dir contains configure.gnu, it is run instead of configure. This is for packages that might use a non-Autoconf script Configure, which can’t be called through a wrapper configure since it would be the same file on case-insensitive file systems. Likewise, if a dir contains configure.in but no configure, the Cygnus configure script found by AC_CONFIG_AUX_DIR is used.

The subdirectory configure scripts are given the same command line options that were given to this configure script, with minor changes if needed, which include:

• - adjusting a relative name for the cache file;
• - adjusting a relative name for the source directory;
• - propagating the current value of $prefix, including if it was defaulted, and if the default values of the top level and of the subdirectory configure differ.

This macro also sets the output variable subdirs to the list of directories ‘dir …’. Make rules can use this variable to determine which subdirectories to recurse into.

This macro may be called multiple times.