Re: [CRAZY PROPOSAL] Automake should support only GNU make

[Bob Friesenhahn]

On Fri, 14 Jan 2011, Ralf Wildenhues wrote:
> (That, by the way, is what nobody ever tells you when they point you to
> the "Recursive Make Considered Harmful" paper: that walking the full
> dependency tree is more expensive than walking a factorized one.  Sure,
> you need to keep the toplevel deps up to date manually then.)

Yes.  Walking the full dependency tree is more expensive, but it is 
also likely that if unnecessary work is done, then even more resources 
are wasted.

I have no idea what project has the largest dependency tree but it 
would surely be one that uses a non-recursive build, or one that puts 
all the source files in one directory.

Regardless, this should not be an argument against an inventory based 
build system which records and saves the actual rules used to build a 
target as well as the timestamp/checksum of the source files to those 
rules (and perhaps, optionally, even the source control version ID for 
thos files).  My argument is that if the target has already been 
built, then only the rules already used need to be checked in order to 
decide if the target needs to be rebuilt.  In case of added/removed 
dependencies such as implicit header file include dependencies, only 
the impacted part of the rules need to be re-checked for validity. 
It is not necessary to rescan the whole world and decide if one of the 
zillion other rules known to 'make' might be used to build the target.

In addition to the above, Automake should be supplying enough explicit 
rule information (pertaining to the actual needs of the current 
project) that the underlying build tool should not have to go off in 
the weeds and try a million other incantations as well.

Anyone who is not familiar with the zillion rules known/tested-by GNU 
make should run 'make -d' on their own projects.

Those that feel that all that counts is the time for a from-scratch 
build and developer rebuilds are not important might consider that 
/bin/sh is a more efficient build tool than 'make' for that particular 
case. :-)

Bob
--
Bob Friesenhahn
address@hidden, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/