Tricky suffix rule problem for Corba

[CARTER-HITCHIN, David, FM]

Hi,

Hope someone out there can help me.

I'm trying to fix a broken rule we have to build CORBA header files.  These
get generated in a two step process from .idl files by a binary called,
funnily enough, idl.  The idl command takes the .idl file and generates a
.cc, then from the .cc it generates a .h.  This is not really at the core of
the problem I'm looking at but I mention this anyway to set the scence.
Incidentally we had a lot of problems with this two stage process until we
put .NOTPARALLEL into the makefiles which disabled our default '-j X'
setting.  Anyway, this is not the problem...

The problem is that we have four modules which require common idl files and
someone recently tidied these up and put them into a common directory at the
same level as the modules.  In other words:

idl/a.idl
idl/b.idl
w/makefile
w/source.cpp
x/makefile
x/source.cpp
y/makefile
y/source.cpp
z/makefile
z/source.cpp

This was a sensible thing to do as sometimes people would change one
instance of an .idl but not the other three. However it created a new
problem:

The rule to build the headers is like this:

%.h %.cc: %.idl
        $(IDL_COMMAND) $(IDL_OPTIONS) $<

This is the problem - the prerequisite $< is '../idl/a.idl' (for example)
and the target is '../idl/a.h' when it should be just 'a.h'.  I say 'should
be' since all our #includes are set up to just look in w,x,y or z and the
way the idl program runs means that it creates the .cc's and .h's in the CWD
which is w,x,y or z.  Is there an *easy* way to fix the rule so the targets
are considered 'a.h' instead of '../idl/a.h'? 

Thanks,

David Carter-Hitchin.
--LongSig


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