Re: FYI: Both: Gr. Reduction

[Akim Demaille]

| It looks like I broke something recently :*(.  1.30 dies, including
| with the patch below, when producing the verbose report (while reading
| tags[-1]).  Also, be frightened, be very frightened:
| 
| | ~/src/bison-1.29 % cd tests/testsuite.dir/17
| | tests/testsuite.dir/17 % cat input.y
| | %verbose
| | %output="input.c"
| | 
| | %nterm useless1
| | %nterm useless2
| | %nterm useless3
| | %nterm useless4
| | %nterm useless5
| | %nterm useless6
| | %nterm useless7
| | %nterm useless8
| | %nterm useless9
| | 
| | %token useful
| | %%
| | exp: useful;
| | tests/testsuite.dir/17 % cat input.output
| | Useless nonterminals:
| | 
| |    exp
| | 
| | 
| | 
| 
| Ahem...

My first guess is that this is the result of my separating generation
from output: I believe that this output used to be produced *before*
the reductions was actually performed.  Now it is certainly done
*after* the reduction was performed.  Therefore, it looks at the slots
where there used to be useless things, which have been removed since
then.

So it is a ``good'' bug: it is the results of something we want
(separation between input/process/output), but it requires some more
work.

I'll try to give it a stab this evening.