"match_co bailing out" messages and compiler crash
$ cat > Blah.hs
{-# LANGUAGE GADTs #-}
module Blah where
blah :: (dd ~ (Double, Double)) => dd -> dd
blah (ax, bx)
| ax < bx = blah (bx, ax)
| otherwise = (0,0)
$ cat > Meh.hs
module Meh where
import Blah
meh = blah (0,0)
If we compile with -O2, in 2 separate calls to ghc, we get:
$ ghc -O2 Blah.hs
[1 of 1] Compiling Blah ( Blah.hs, Blah.o )
match_co baling out
<(ghc-prim:GHC.Types.Double{(w) tc 3u},
ghc-prim:GHC.Types.Double{(w) tc 3u})>
match_co baling out
<(ghc-prim:GHC.Types.Double{(w) tc 3u},
ghc-prim:GHC.Types.Double{(w) tc 3u})>
match_co baling out
<(ghc-prim:GHC.Types.Double{(w) tc 3u},
ghc-prim:GHC.Types.Double{(w) tc 3u})>
match_co baling out
<(ghc-prim:GHC.Types.Double{(w) tc 3u},
ghc-prim:GHC.Types.Double{(w) tc 3u})>
match_co baling out
<(ghc-prim:GHC.Types.Double{(w) tc 3u},
ghc-prim:GHC.Types.Double{(w) tc 3u})>
match_co baling out
<(ghc-prim:GHC.Types.Double{(w) tc 3u},
ghc-prim:GHC.Types.Double{(w) tc 3u})>
$ ghc -O2 Meh.hs
[2 of 2] Compiling Meh ( Meh.hs, Meh.o )
ghc: panic! (the 'impossible' happened)
(GHC version 7.4.2 for x86_64-unknown-linux):
tcIfaceType
Refl
(ghc-prim:GHC.Types.Double{(w) tc 3u},
ghc-prim:GHC.Types.Double{(w) tc 3u})
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
Trac metadata
| Trac field | Value |
|---|---|
| Version | 7.7 |
| Type | Bug |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | Compiler |
| Test case | |
| Differential revisions | |
| BlockedBy | |
| Related | |
| Blocking | |
| CC | |
| Operating system | |
| Architecture |