Hello,
I've read the documentation and created samples to learn a bit about Happy so I can debug the Haskell grammar for GHC.
This document here: https://github.com/haskell/happy/blob/master/doc/tips.rst
States that when there is a reduce/reduce conflict, the reduction rule that is the uppermost in the grammar file is picked.
Attached is a sample grammar with a main method. This file shows that at least here, not the first, but the last reduction rule is fixed.
Please have a look. If I understood things right and didn't mess it up in my sample code, then either Happy has a bug in its code generation or this is intended design and the documentation reflects this wrong. :)
In ReduceReduceConflict, A should be picked, but B is picked.
This is made visible through the evaluation of test "#1" 3 in main (it should be OK for 2 and Not OK for 3).
Kind regards,
Hai
bug-reduce-reduce-conflict.y.txt
Hello,
I've read the documentation and created samples to learn a bit about Happy so I can debug the Haskell grammar for GHC.
This document here: https://github.com/haskell/happy/blob/master/doc/tips.rst
States that when there is a reduce/reduce conflict, the reduction rule that is the uppermost in the grammar file is picked.
Attached is a sample grammar with a main method. This file shows that at least here, not the first, but the last reduction rule is fixed.
Please have a look. If I understood things right and didn't mess it up in my sample code, then either Happy has a bug in its code generation or this is intended design and the documentation reflects this wrong. :)
In
ReduceReduceConflict,Ashould be picked, butBis picked.This is made visible through the evaluation of
test "#1" 3inmain(it should be OK for2and Not OK for3).Kind regards,
Hai
bug-reduce-reduce-conflict.y.txt