Re: How to write rule that gets all items referenced in a given makefile

[Adrian Muresan]

Someone at stackoverflow gave me the answer:


    %:: null
        @:

    null:
        @:

which I pass in like so: `make all MAKEFILES=Dummy.mk`


This captures ALL the files. The double-colon is "terminal rule" (see 
https://www.gnu.org/software/make/manual/make#Match_002dAnything-Rules)


When I run this, for every single target I get a statement


:2: update target <target> due to: null


And in the `--print-data-base` section, there is no file that is listed as `# 
Not a target`, only the 68 implicit rules.


This solution appears to only work on Windows: someone said they tried this on 
Linux and it doesn't work

http://stackoverflow.com/questions/38250056/gnu-make-terminal-rules-and-keyword-null/38252249#comment63925596_38252249





________________________________
From: Tim Murphy <address@hidden>
Sent: Wednesday, July 6, 2016 12:38 AM
To: Adrian Muresan
Cc: address@hidden
Subject: Re: How to write rule that gets all items referenced in a given 
makefile

Ok, so you want the state of make just after parsing finishes.  Without 
patching make or modifying every rule I think your plan for using the printed 
database is the best you can manage.   The database output is quicker to parse 
than your original makefile usually.

If your makefiles use $(shell) then that might possibly cause trouble with this 
scheme.

Regards,

Tim

On 6 July 2016 at 07:13, Adrian Muresan <address@hidden<mailto:address@hidden>> 
wrote:
Yes, I am using it and yes the info it gives is very useful, parseable and 
excellent in general.

The problem is that this information is only outputted by `make` AFTER the 
makefile is finished executing whereas I need to access this information - via 
some function that apparently doesn't exist - BEFORE the makefile rules start 
executing so that I can create rules that act on his information.

As it stands, I'd have to run my build twice: once to get the info and another 
time to use the info.

Given my esoteric task, it's not unreasonable for me to do this.

1. Make all
2. Parse output, generate whatever rules I need -> Generated_Rules.mk
3. Make all MAKEFILES=Generated_Rules.mk

> On Jul 5, 2016, at 11:44 PM, Tim Murphy 
> <address@hidden<mailto:address@hidden>> wrote:
>
> You might want to use makes -p option (--print-data-base) to print out the 
> targets and prereqs that it has read.   The format of this output is 
> simplified - all variables etc are expanded - so in python it's very easy to 
> parse.
>
> Regards,
>
> Tim