The -bk patch-set contains a number of reasonably backwards-compatible 
bug-fixes and improvements for GNU make. It is released against the 
official GNU make; the part before -bkN indicates GNU make version 
('cvs' stands for CVS snapshot).

The latest version is available from 

ftp://kolpackov.net/pub/projects/make/bk/

To apply the patch-set execute something like this in the source 
directory:

$ cat ../cvs-bkN/*.patch | patch -p1

You can also apply individual patches with the following command:

$ cat ../cvs-bkN/*-<patch-name>.patch | patch -p1


Below is the list of patches with descriptions included in this 
release.

Since cvs-bk5:

  ~ implicit-double-expansion.patch

    Two new features:

      * Special ($@, $<, etc) and target/pattern-specific variables 
        are now available in second expansion. See examples/vdep for 
        an example of how this can be used.


      * New special variable $- is recognized during second expansion
        which instructs make to remove prerequisites of the target
        under consideration that did not come from this implicit rule.
        
        Now you can write something like this:

        foo.o: foo.c foo.h

        %.o: %.c.md5 $$(addsuffix\ .md5,$$^) $$-
		$(CC) -o $@ -c $(<:.md5=)

        Which will change prerequisites `foo.c' and `foo.h' to become
        `foo.c.md5' and `foo.h.md5' respectively. See examples/md5 for
        details.


  + pattern-specific-export.patch

    Fixes bug that manifests itself in exported pattern-specific
    variables not being exported. See tests/pattern-specific-export
    for details.


Since cvs-bk4:


  + not-default.patch

    New special target .NOT_DEFAULT. Prerequisites of this target are
    not considered for default target. Note that you have to specify
    that target is not default before actually defining the it, e.g., 
    the following will not work:

    foo: bar
    .NOT_DEFAULT: foo


  ~ dontcare-inheritance.patch

    Updated to work properly with the recent changes to the "dontcare"
    machinery. With this patch and changes from Paul (in cvs head) both
    bugs described in 

    http://mail.gnu.org/archive/html/bug-make/2004-02/msg00014.html

    are fixed.
    

  - first-prerequisite.patch
  
    Fixed in the main trunk.


Since cvs-bk3:


  + first-prerequisite.patch

    This patch fixes a bug that manifests itself by an order-only
    prerequisite ending up in $< automatic variable.

    See
    
    http://mail.gnu.org/archive/html/bug-make/2004-04/msg00018.html

    for more information.
    

  + pattern-specific-expansion.patch

    The following makefile prints 'B' instead of 'A'.

      a := A

      %bar : arg := $a
      %bar : ; @echo $(arg)

      a := B

      foobar:

    
    The patch adds additional expansion at pattern definition 
    point for simple variables (i.e. declared with :=). Also 
    note that you can inhibit this additional expansion if 
    you want to:


      %bar : arg := $a $$a

   
    With this change the makefile above prints 'A B'.


    See 

    http://mail.gnu.org/archive/html/bug-make/2004-04/msg00005.html

    for more information.


  + realpath.patch

    Implements $(realpath ) function. See realpath(3) for details.


  ~ no-implicit-phony.patch

    Experience has shown that some build systems depend on the 
    implicit phony logic (well, actually their developers simply 
    forget to declare phony targets explicitly). 
    Thus the no-implicit-phony feature is now off by default and 
    should be turned on explicitly. There are two ways to do this:

    1. Use command line flag --no-implicit-phony


    2. Use MAKEFLAGS variable from inside a makefile. The 
       corresponding makefile fragment might look like this

       ifneq ($(findstring --no-implicit-phony,$(MAKEFLAGS)),)

         MAKEFLAGS += --no-implicit-phony

       endif



Since cvs-bk2:


  + no-implicit-phony.patch

    This patch inhibits make's ability to assume targets are phony.
    For example consider the following makefile:

    foo.o: foo.c
        @echo building foo.o

    foo.c: foo.ext

    foo.ext:
        @echo building foo.ext

    
    Even though there is no actual rule to build 'foo.c' make assumes
    that this target is phony and is "somehow" updated . With this
    patch installed make will issue an error unless 'foo.c' is
    explicitly declared phony.

    See

    http://mail.gnu.org/archive/html/help-make/2004-02/msg00028.html

    for additional information.



Since cvs-bk1:


  + lastword.patch

    Implements $(lastword ) function which is similar to 
    $(firstword). See

    http://savannah.gnu.org/patch/?func=detailitem&item_id=2483

    for more information.


  + implicit-double-expansion.patch

    Implements double expansion in implicit rules. Now make expands 
    prerequisites of an implicit rule twice: first time when make reads
    the file and second time when make tries to match an implicit rule
    after the stem (%) substitution. Note that you need to escape '$' if
    you want the expansion to be delayed. Also you need to escape spaces
    if you don't want them to be treated as a prerequisite separator. The
    following example hopefully gives an idea how this could be useful:


    /%.o : $$(notdir\ %.c) | $$(dir\ /%).
    	gcc -c -o $@ $<


    .PRECIOUS: %/.

    %/. :
    	mkdir -p $*


    $(CURDIR)/i386/foo.o :


  + dontcare-inheritance.patch

    This is a somewhat partial fix for the problem described in the
    following thread:

    http://mail.gnu.org/archive/html/bug-make/2004-02/msg00014.html


    In particular the following makefile works as one would expect:

    -include bar

    hello:
    	@echo hello

    bar : foo
    	cp foo bar


  + version.patch

    Adds -bkN to the make version and an additional copyright clause.