Shift/reduce conflicts

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Shift/reduce conflicts

Twan van Laarhoven
I just noticed that on HEAD, happy reports for Parser.y.pp:

     $ happy -agc --strict  compiler/stage1/build/Parser.y
     unused rules: 2
     shift/reduce conflicts:  49
     reduce/reduce conflicts: 1

But the code claims:

     12 October 2012

     Conflicts: 43 shift/reduce
                1 reduce/reduce

So somewhere recently we have picked up 6 additional shift/reduce conflicts.


Twan


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Shift/reduce conflicts

Simon Peyton Jones
Oh bother.  I have no idea.  If anyone feels able to bisect their way to the culprit, that would be good.

Simon

| -----Original Message-----
| From: ghc-devs-bounces at haskell.org [mailto:ghc-devs-bounces at haskell.org]
| On Behalf Of Twan van Laarhoven
| Sent: 27 May 2013 13:00
| To: ghc-devs at haskell.org
| Subject: Shift/reduce conflicts
|
| I just noticed that on HEAD, happy reports for Parser.y.pp:
|
|      $ happy -agc --strict  compiler/stage1/build/Parser.y
|      unused rules: 2
|      shift/reduce conflicts:  49
|      reduce/reduce conflicts: 1
|
| But the code claims:
|
|      12 October 2012
|
|      Conflicts: 43 shift/reduce
|                 1 reduce/reduce
|
| So somewhere recently we have picked up 6 additional shift/reduce conflicts.
|
|
| Twan
|
| _______________________________________________
| ghc-devs mailing list
| ghc-devs at haskell.org
| http://www.haskell.org/mailman/listinfo/ghc-devs


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Shift/reduce conflicts

Thorkil Naur
Hello,

On Mon, May 27, 2013 at 01:01:48PM +0000, Simon Peyton-Jones wrote:
> Oh bother.  I have no idea.  If anyone feels able to bisect their way to the culprit, that would be good.

There seems to be multiple culprits: Between

  http://darcs.haskell.org/ghcBuilder/builders/tn23/751

and

  http://darcs.haskell.org/ghcBuilder/builders/tn23/752

shift/reduce conflicts went from 43 to 45. A likely candidate is

  df04d2d875f4f17b04cd8bd396b62b1eadd932e8 Allow '-' to be used as an infix type constructor.

Between

  http://darcs.haskell.org/ghcBuilder/builders/tn23/788

and

  http://darcs.haskell.org/ghcBuilder/builders/tn23/789

shift/reduce conflicts went to 47 with

  8366792eede3c8eb486ff15d8c8e62e9363f1959 Implement overlapping type family instances.

a likely candidate. Finally, between

  http://darcs.haskell.org/ghcBuilder/builders/tn23/806

and (there is no data for build 807)

  http://darcs.haskell.org/ghcBuilder/builders/tn23/808

shift/reduce conflicts went to 49 with

  deec5b74dee7f676b8a9f840ec7b5a813e7e0956 Be willing to parse {-# UNPACK #-} without '!'

a likely candidate.

> ...

Best regards
Thorkil