GnuMake's debug output sometimes incorrect for pattern rules?

[Grothausmann, Roman Dr.]

Dear mailing list members,


Referring to https://github.com/lindenb/makefile2graph/issues/12 :
I'm using make2graph (https://github.com/lindenb/makefile2graph) in order to 
visualize dependencies that Make finds. Apart from similar contributions, 
make2graph uses Make itself to parse and interpret dependencies implied by a 
given Makefile by using its debug output. For me this yields the best results 
for complex makefiles, especially when GnuMake specifics are used.
However, GnuMakes debug output seems to yield different dependencies depending 
on whether a file already exists or not, see description in 
https://github.com/lindenb/makefile2graph/issues/12.
Using make -Bt can be used as a workaround, but this removes the possibility to 
create a Make-Dep-Graph from an intermediate state, i.e. just a sub-graph from 
the complete graph.

Is there any way to get GnuMake to output debug messages that do not lead to 
false dependencies even when files do not yet exist?
Or is there a way to adjust make2graph to recognise such false dependencies?

Any help, hints or other ideas are very much appreciated as well as explanations 
why GnuMakes output differs in this case.
Roman

--
Dr. Roman Grothausmann

Tomographie und Digitale Bildverarbeitung
Tomography and Digital Image Analysis

Institut für Funktionelle und Angewandte Anatomie, OE 4120
Medizinische Hochschule Hannover
Carl-Neuberg-Str. 1
D-30625 Hannover

Tel. +49 511 532-2900