Panic in tidyNPat when using N+k patterns with overloaded strings
Spotted this while reading the source code to tidyNPat. It looked dubious to me, and indeed it is:
{-# OPTIONS_GHC -XOverloadedStrings #-}
module Main where
import Data.String
instance IsString Int where
fromString x = 1337
f :: Int -> String
f "hello" = "correct"
f _ = "false"
main = do
print $ f 1337
print $ f 1338
Result:
mbolingbroke@mb566 ~/Programming/Checkouts
$ ghc --make Boog.hs
[1 of 1] Compiling Main ( Boog.hs, Boog.o )
ghc: panic! (the 'impossible' happened)
(GHC version 6.10.3 for i386-apple-darwin):
tidyNPat
Trac metadata
Trac field | Value |
---|---|
Version | 6.10.4 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |