Re: Automatic macro dependencies

[Harvey Chapman]

Sam Ravnborg wrote:
> http://www.kernel.org :-)
>
> In the kernel we use a lot of CONFIG_ named variables and
> changing one of these cause the relevant files to be rebuilt.
>
> The steps are basically:....

Ah, thanks to all that replied. This is what I was looking for. I know 
that make doesn't do what I want. I was looking for a recipe or a 
pointer to a possible solution. I figured someone must have done this 
before. This sounds like what I'm looking for. All of my macros start 
with DEBUG_. I'll take a look at how the kernel does it. If I get it 
working, I'll post a complete example solution here as thanks and also 
to solicit suggestions.

The end result will have to scan each source file and build a list of 
DEBUG_ macros it uses. Then a master list will have to be compared to a 
previous master list to see if the master list has changed. If it has, 
we make a list of macros that have been added or removed and recompile 
all source files with intersecting macro lists. The recompiling could 
occur by making the changed list a dependency of source files that 
intersect or perhaps touching the source file.

So:

Flags that might be used: DEBUG_A DEBUG_B DEBUG_C DEBUG_D

ROUND 1
-------

Master List: DEBUG_A DEBUG_B DEBUG_C

source1.c uses DEBUG_A and DEBUG_B
source2.c uses DEBUG_B and DEBUG_C
source3.c uses DEBUG_D

Compile...

ROUND 2
-------

Change master list to: DEBUG_A DEBUG_B DEBUG_D

We see that it doesn't match the old list (presumably saved in a file).
We make a changed list (one removed, one added): DEBUG_C DEBUG_D

Re-compile any file that uses a macro in the change list.
source2.c and source3.c are recompiled.



I have enough to get started, and I'll post back with the results.

Many thanks,

H.