[PATCH v2 0/5] Lazily generate header dependencies

[Jonathan Nieder <jrnieder@gmail.com>]

Nanako Shiraishi wrote:
> Junio, could you tell us what happened to this thread?
> 
> Makefile improvements.  No discussion.

My bad.  The previous version was very rough because I was not sure
yet how this could help in making the header dependency rules more
maintainable.  If all compilers worth using support something like
gcc's -MD option (does MSVC?), we could switch over completely;
otherwise, we need some way to use the generated dependencies to
check the static ones, or the static ones will go stale.

That is, maybe something like this.  With these patches applied,
running

	echo COMPUTE_HEADER_DEPENDENCIES=YesPlease >> config.mak
	make clean
	make
	make CHECK_HEADER_DEPENDENCIES=YesPlease

will fail unless the dependency rules in the Makefile account for
all #includes gcc noticed with the current configuration.

Patch 5 is a little rough around the edges, but I am hoping it
will convey the idea.

Enjoy,
Jonathan Nieder (5):
  Makefile: rearrange dependency rules
  Makefile: clear list of default rules
  Makefile: list generated object files in OBJECTS macro
  Makefile: lazily compute header dependencies
  Teach Makefile to check header dependencies

 .gitignore |    1 +
 Makefile   |  158 +++++++++++++++++++++++++++++++++++++++++++++++++-----------
 2 files changed, 130 insertions(+), 29 deletions(-)