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_LIBADD, _LDFLAGS, and _LIBTOOLFLAGSAs shown in previous sections, the ‘library_LIBADD’ variable should be used to list extra libtool objects (.lo files) or libtool libraries (.la) to add to library.
The ‘library_LDFLAGS’ variable is the place to list additional libtool linking flags, such as -version-info, -static, and a lot more. See Link mode in The Libtool Manual.
The libtool command has two kinds of options: mode-specific
options and generic options. Mode-specific options such as the
aforementioned linking flags should be lumped with the other flags
passed to the tool invoked by libtool (hence the use of
‘library_LDFLAGS’ for libtool linking flags). Generic
options include --tag=tag and --silent
(see Invoking libtool in The
Libtool Manual for more options) should appear before the mode
selection on the command line; in Makefile.ams they should
be listed in the ‘library_LIBTOOLFLAGS’ variable.
If ‘library_LIBTOOLFLAGS’ is not defined, then the variable
AM_LIBTOOLFLAGS is used instead.
These flags are passed to libtool after the --tag=tag
option computed by Automake (if any), so
‘library_LIBTOOLFLAGS’ (or AM_LIBTOOLFLAGS) is a
good place to override or supplement the --tag=tag
setting.
The libtool rules also use a LIBTOOLFLAGS variable that should
not be set in Makefile.am: this is a user variable (see Flag Variables Ordering. It allows users to run ‘make
LIBTOOLFLAGS=--silent’, for instance. Note that the verbosity of
libtool can also be influenced with the Automake
silent-rules option (see Changing Automake’s Behavior).