Currently, in a project that uses the 'configmake' module, modifying
lib/Makefile can cause an avalanche of rebuilds during the next "make".
In my case, it's because we have dependencies
configmake.h from Makefile,
config.h from $(BUILT_SOURCES), which contains configmake.h,
all *.o files from config.h
It's actually unnecessary to rebuild all this if the contents of configmake.h
actually did not change. I'm committing this optimization:
2009-04-19 Bruno Haible <br...@clisp.org>
* modules/configmake (Makefile.am): When the contents of configmake.h
does not change, arrange to preserve its modification time.
*** modules/configmake.orig 2009-04-19 22:05:35.000000000 +0200
--- modules/configmake 2009-04-19 21:56:12.000000000 +0200
***************
*** 26,32 ****
# The Automake-defined pkg* macros are appended, in the order
# listed in the Automake 1.10a+ documentation.
configmake.h: Makefile
! rm -f $...@-t $@
{ echo '/* DO NOT EDIT! GENERATED AUTOMATICALLY! */'; \
echo '#define PREFIX "$(prefix)"'; \
echo '#define EXEC_PREFIX "$(exec_prefix)"'; \
--- 26,32 ----
# The Automake-defined pkg* macros are appended, in the order
# listed in the Automake 1.10a+ documentation.
configmake.h: Makefile
! rm -f $...@-t
{ echo '/* DO NOT EDIT! GENERATED AUTOMATICALLY! */'; \
echo '#define PREFIX "$(prefix)"'; \
echo '#define EXEC_PREFIX "$(exec_prefix)"'; \
***************
*** 56,62 ****
echo '#define PKGLIBDIR "$(pkglibdir)"'; \
echo '#define PKGLIBEXECDIR "$(pkglibexecdir)"'; \
} | sed '/""/d' > $...@-t
! mv $...@-t $@
BUILT_SOURCES += configmake.h
CLEANFILES += configmake.h configmake.h-t
--- 56,67 ----
echo '#define PKGLIBDIR "$(pkglibdir)"'; \
echo '#define PKGLIBEXECDIR "$(pkglibexecdir)"'; \
} | sed '/""/d' > $...@-t
! if test -f $@ && cmp $...@-t $@ > /dev/null; then \
! rm -f $...@-t; \
! else \
! rm -f $@; mv $...@-t $@; \
! fi
!
BUILT_SOURCES += configmake.h
CLEANFILES += configmake.h configmake.h-t
