Problem using same .y file in multiple libs and AM_YFLAGS=-d

[Sander Niemeijer]

Hi all,

I am using a yacc/bison source file in a libtool library, but I create 
both an installable static/shared version of the library as well as an 
internal convenience library (so I can later on link the PIC objects 
directly into another shared library). Since I need the header file 
with the parser definitions I use the "AM_YFLAGS = -d" option to have 
automake do this for me.

The problem is that automake (1.7.7) doesn't see that the .y source 
files in the _SOURCES definitions of two libraries (the installable one 
and the internal convenience one) are actually the same and thus, 
because of the AM_YFLAGS definition, creates two identical rules in the 
final Makefile for the .h file. This is something the make program 
obviously doesn't like and I therefore receive a 'warning: overriding 
commands for target' warning.

A simple Makefile.am example that shows this behavior is:
---
AM_YFLAGS = -d

lib_LTLIBRARIES = libfoo.la
noinst_LTLIBRARIES = libfoo_internal.la

BUILT_SOURCES = foo.h

libfoo_la_SOURCES = foo.y
libfoo_la_LDFLAGS = -version-info 0:0:0

libfoo_internal_la_SOURCES = foo.y
---

Does anybody know how I can get rid of the make warnings (and, just out 
of interest, will these warnings stay warnings when I use a different 
make program instead of GNU make, or might other make programs see the 
double .h rule definition as an error)?

P.S. I also have, for anyone who is interested, a small example package 
available with just a single .y file that reproduces the problem.

Regards,
Sander Niemeijer