(make.info)Archive Update


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Implicit Rule for Archive Member Targets
========================================

   Recall that a target that looks like `A(M)' stands for the member
named M in the archive file A.

   When `make' looks for an implicit rule for such a target, as a
special feature it considers implicit rules that match `(M)', as well as
those that match the actual target `A(M)'.

   This causes one special rule whose target is `(%)' to match.  This
rule updates the target `A(M)' by copying the file M into the archive.
For example, it will update the archive member target `foo.a(bar.o)' by
copying the *file* `bar.o' into the archive `foo.a' as a *member* named
`bar.o'.

   When this rule is chained with others, the result is very powerful.
Thus, `make "foo.a(bar.o)"' (the quotes are needed to protect the `('
and `)' from being interpreted specially by the shell) in the presence
of a file `bar.c' is enough to cause the following commands to be run,
even without a makefile:

     cc -c bar.c -o bar.o
     ar r foo.a bar.o
     rm -f bar.o

Here `make' has envisioned the file `bar.o' as an intermediate file.
Note: Chains of Implicit Rules.

   Implicit rules such as this one are written using the automatic
variable `$%'.  Note: Automatic Variables.

   An archive member name in an archive cannot contain a directory
name, but it may be useful in a makefile to pretend that it does.  If
you write an archive member target `foo.a(dir/file.o)', `make' will
perform automatic updating with this command:

     ar r foo.a dir/file.o

which has the effect of copying the file `dir/file.o' into a member
named `file.o'.  In connection with such usage, the automatic variables
`%D' and `%F' may be useful.

* Archive Symbols
How to update archive symbol directories.

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