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

[Bob Friesenhahn]

On Thu, 13 Jan 2011, Guido Draheim wrote:
> * ClearCase - ships clearmake integrated with the build systems.
> and there are sure some other build systems that have a frontend to
> the user allowing for makefiles as the backend.

FYI, ClearCase's clearmake is actually based on GNU make source code. 
At least it was back when I was using it.

ClearCase is an example of a build system which does produce a build 
'inventory' recording exactly how the target was built.  It 
accomplishes that by studying the I/O requests from the build tools.

Regardless, 'make's use of timestamps based on simple "newer than" 
analsys is not very robust in our real world.  A build system which at 
least records the absolute time stamps (and preferably a checksum) for 
everything used to build a built target is much more capable of 
knowing what needs to be rebuilt if something is changed.  If a source 
file becomes "older" and its content has changed, then anything 
depending on it needs to be rebuilt (which existing make will not do). 
If the source file somehow becomes "older" but its content has not 
changed, then the associated timestamp in the build inventory can be 
updated and nothing needs to be rebuilt.  In this case, the timestamp 
is simply an optimization.

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