Opened 5 years ago

Closed 4 years ago

Last modified 4 years ago

#10426 closed bug (fixed)

matchGroupArity panic with PatternSynonyms

Reported by: Iceland_jack Owned by:
Priority: normal Milestone: 8.0.1
Component: Compiler Version: 7.10.1
Keywords: PatternSynonyms Cc: mpickering, cactus
Operating System: Unknown/Multiple Architecture: Unknown/Multiple
Type of failure: None/Unknown Test Case: T10426
Blocked By: Blocking:
Related Tickets: Differential Rev(s): Phab:D1665
Wiki Page:


{-# LANGUAGE PatternSynonyms, ViewPatterns, EmptyCase #-}

pattern Id <- (id -> _) where

which gives:

% ghc -ignore-dot-ghci tmp.FbbzjZ48OO.hs 
[1 of 1] Compiling Main             ( tmp.FbbzjZ48OO.hs, tmp.FbbzjZ48OO.o )
ghc: panic! (the 'impossible' happened)
  (GHC version for i386-unknown-linux):

Please report this as a GHC bug:

Change History (8)

comment:1 Changed 4 years ago by thomie

Architecture: x86Unknown/Multiple
Cc: mpickering cactus added
Keywords: PatternSynonyms added
Operating System: LinuxUnknown/Multiple

Not fixed yet in ghc-7.11.20151019.

comment:2 Changed 4 years ago by Ben Gamari <ben@…>

In fdb08e2/ghc:

Add testcase for #10426

comment:3 Changed 4 years ago by bgamari

Test Case: T10426

comment:4 Changed 4 years ago by mpickering

Differential Rev(s): Phab:D1665
Status: newpatch

comment:5 Changed 4 years ago by Matthew Pickering <matthewtpickering@…>

In 8d954125/ghc:

Disallow empty where bindings in pattern synonym declarations.

Reviewers: austin, bgamari

Reviewed By: bgamari

Subscribers: thomie

Differential Revision:

GHC Trac Issues: #10426

comment:6 Changed 4 years ago by mpickering

Resolution: fixed
Status: patchclosed

comment:7 Changed 4 years ago by Simon Peyton Jones <simonpj@…>

In b55ad1b3/ghc:

Wibble to error message in Trac #10426

comment:8 Changed 4 years ago by thomie

Milestone: 8.0.1
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