Bison/YACC suffix bug

[Michael Blumenkrantz]

Hi,

It seems that there is a bug with yacc filename suffixes, though I am unsure 
under which conditions it triggers.

I have a makefile here which defines AM_YFLAGS = -d:
http://git.enlightenment.org/devs/discomfitor/maelstrom.git/tree/src/bin/azy.mk

The issue is that when running yacc (bison -y) on re_parser.ypp, there are two 
possible filenames which are output:

* re_parser.h
* re_parser.hpp

It seems to be impossible to know which file will be created; the only 
consistency is that a system will always generate the same name. Systems with 
the latest software tend to generate the .hpp file (which is correct according 
to the manual), while older systems create the .h file.

Is this a known bug or something, and is there a fix for it?