Libtool supports multiple languages through the use of tags. Technically a tag corresponds to a set of configuration variables associated with a language. These variables tell libtool how it should create objects and libraries for each language.
Tags are defined at configure-time for each language activated
in the package (see
LT_LANG in LT_INIT). Here is the
correspondence between language names and tags names.
|Language name||Tag name
libtool tries to automatically infer which tag to use from
the compiler command being used to compile or link. If it can't infer
a tag, then it defaults to the configuration for the
The tag can also be specified using libtool's
--tag=tag option (see Invoking libtool). It is a good
idea to do so in Makefile rules, because that will allow users to
substitute the compiler without relying on libtool inference
heuristics. When no tag is specified, libtool will default
CC; this tag always exists.
Finally, the set of tags available in a particular project can be
retrieved by tracing for the
LT_SUPPORTED_TAG macro (see Trace interface).