+++ /dev/null
-# rule how to make the file containing all the forward declarations
-# taken from the deal.II Makefile
-#
-# this rule is rather complicated, it works as follows:
-#
-# - if this is the outermost 'make', then create a file $@.old.
-# if the forward declaration file $@ already exists, then copy
-# it over, otherwise leave it empty. this way, we always have
-# a file to run diff on. send the output of the copy command
-# (which may fail) to nirvana.
-# - write the forward declarations for the presently available
-# header files to $@.new
-# - we would like to compare the output of the script generating
-# the forward declarations with the old file, or the empty
-# string if there is no such file; this is why we created $@.old
-# - if the files differ, we would like to copy over the old file.
-# - this can either be done using shell programming using 'if [...]'
-# or using conditionals inside 'make'. the first way is not
-# portable over different shells, however, and I also do not know
-# how to write it. the second way has a problem also: conditionals
-# are evaluated at the time the Makefile is read first, so we
-# can't compare against $@.old, since this file does not exist at
-# that time.
-# - we therefore invoke a second 'make', which can compare the two
-# files against each other in a preconditional clause and
-# copy over the file if necessary.
-# - delete the two temporary files
-$(forward-declarations): $(filter-out %forward-declarations%,$(h-files))
-ifneq (1,${recursive-make-fwd-decl})
- @echo ============================ Checking $@
- @touch $@.old
- -@cp $@ $@.old > /dev/null 2>&1
- @perl $D/common/scripts/Make_forward_declarations.pl $(filter-out %forward-declarations.h,$(h-files)) > $@.new
- @make --silent recursive-make-fwd-decl=1 $@
- @rm $@.old $@.new
-else
- ifneq (,$(shell diff $(forward-declarations).old $(forward-declarations).new))
- @echo ============================ Generating $@
- @cp $@.new $@
- else
- @echo "============================ $@ needs no change"
- endif
-endif