Re: (no subject)

[Philip Guenther]

On 2/22/07, address@hidden
<address@hidden> wrote:
> I'm having a problem with automatic dependency generation from source-files
> that depend on  auto-generated header files.

The order-only prerequisites added to GNU Make in version 3.80 provide
a fairly clean solution for this.  In order for the make to succeed
before any dependency information have been generated, make will need
to build the auto-generated files first.  So, add an order-only
dependency of all the object files on the auto-generated files.


> SRC := main.cpp A.cpp   # NOTE: A.cpp is auto-generated by the IDL tool
> OBJS := $(SRC:.cpp=.o)
> DEPS := $(SRC:.cpp=.d)

$(OBJS): | A.cpp


...
> * I could make some phony targets and make sure that all auto-generation
> steps are performed  first. This doesn't help much though when the
> auto-generated files are in another module. I  would have to litter the
> makefiles with "high-level" dependecies between modules. I suspect  that
> this will quickly deteriorate to a scheme that will be equivalent to
> remaking all other  modules prior to making the current module.

IMHO, the problem here is that the overall setup is broken.  If the
modules are truly independent, then install the dependent module's
'output' files somewhere for use by the other modules instead of
(re)building them as part of other modules.  If they *aren't*
independent, then go read the "Recursive Make Considered Harmful"
paper and stop pounding your head on the problems that recursive make
creates.


(After reading that paper many years ago, I redid the make setup on
the project I work on to not be recursive and the results have been
wonderful.  The biggest problem was that an earlier version of the
project that still used recursive make was maintained for most of the
period: whenever I had to fix something in the old version, I had to
suffer through the problems of the uncorrected build system.  The
project currently has 9 auto-generated source files in 5 directories
out of over 600 source files in 87 directories.)


Philip Guenther