#5971: Referencing a newName in a VarE without definition triggers "the
impossible
happened"
--------------------------------+-------------------------------------------
Reporter: josh | Owner:
Type: bug | Status: new
Priority: normal | Component: Compiler
Version: 7.4.1 | Keywords:
Os: Unknown/Multiple | Architecture: Unknown/Multiple
Failure: Compile-time crash | Testcase:
Blockedby: | Blocking:
Related: |
--------------------------------+-------------------------------------------
Test case:
{{{
{-# LANGUAGE TemplateHaskell #-}
import Language.Haskell.TH
_ = $(newName "x" >>= varE)
}}}
Result:
{{{
$ runghc test.hs
ghc: panic! (the 'impossible' happened)
(GHC version 7.4.1 for x86_64-unknown-linux):
nameModule x_aSd{v}
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
}}}
Similar results from ghci:
{{{
$ ghci
GHCi, version 7.4.1: http://www.haskell.org/ghc/ :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ... done.
Loading package base ... linking ... done.
Prelude> :set -XTemplateHaskell
Prelude> import Language.Haskell.TH
Prelude Language.Haskell.TH> $(newName "x" >>= varE)
Loading package array-0.4.0.0 ... linking ... done.
Loading package deepseq-1.3.0.0 ... linking ... done.
Loading package containers-0.4.2.1 ... linking ... done.
Loading package pretty-1.1.1.0 ... linking ... done.
Loading package template-haskell ... linking ... done.
ghc: panic! (the 'impossible' happened)
(GHC version 7.4.1 for x86_64-unknown-linux):
nameModule x_aSm{v}
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
}}}
Note that referencing an undefined name via mkName generates a reasonable
error message rather than "the impossible happened":
{{{
Prelude Language.Haskell.TH> $(varE $ mkName "x")
<interactive>:6:3:
Not in scope: `x'
In the result of the splice:
$(varE $ mkName "x")
To see what the splice expanded to, use -ddump-splices
In the expression: $(varE $ mkName "x")
In an equation for `it': it = $(varE $ mkName "x")
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5971>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
_______________________________________________
Glasgow-haskell-bugs mailing list
[email protected]
http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
