#2631: Template Haskell weird error message
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Reporter: NeilMitchell | Owner:
Type: bug | Status: new
Priority: normal | Component: Template Haskell
Version: 6.9 | Severity: normal
Keywords: | Testcase:
Architecture: Unknown | Os: Unknown
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I've noticed quite a few bugs related to weird TemplateHaskell expressions
crashing the compiler recently, so I thought I'd try and write a nice
exhaustive test of []'s in all possible places. In doing so however, I got
some fairly weird error messages:
{{{
C:\Neil\temp>cat Main.hs
{-# LANGUAGE TemplateHaskell #-}
module Main where
import Language.Haskell.TH
main _ = $( return $ CompE [])
C:\Neil\temp>ghci Main.hs
GHCi, version 6.9.20080916: http://www.haskell.org/ghc/ :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer ... linking ... done.
Loading package base ... linking ... done.
[1 of 1] Compiling Main ( Main.hs, interpreted )
Loading package syb ... linking ... done.
Loading package array-0.1 ... linking ... done.
Loading package packedstring-0.1 ... linking ... done.
Loading package containers-0.1 ... linking ... done.
Loading package pretty-1.0 ... linking ... done.
Loading package template-haskell ... linking ... done.
Ok, modules loaded: Main.
*Main> main ()
<interactive>:1:0:
Can't find interface-file declaration for variable main
Probable cause: bug in .hi-boot file, or inconsistent .hi file
Use -ddump-if-trace to get an idea of which file caused the error
In the expression: main ()
In the definition of `it': it = main ()
*Main> :q
Leaving GHCi.
C:\Neil\temp>ghc --make Main.hs
[1 of 1] Compiling Main ( Main.hs, Main.o )
Loading package ghc-prim ... linking ... done.
Loading package integer ... linking ... done.
Loading package base ... linking ... done.
Loading package syb ... linking ... done.
Loading package array-0.1 ... linking ... done.
Loading package packedstring-0.1 ... linking ... done.
Loading package containers-0.1 ... linking ... done.
Loading package pretty-1.0 ... linking ... done.
Loading package template-haskell ... linking ... done.
Linking Main.exe ...
Main.o:fake:(.text+0x4d): undefined reference to `Main_main_closure'
Main.o:fake:(.data+0x4): undefined reference to `Main_main_closure'
collect2: ld returned 1 exit status
}}}
The main binding seems to get dropped, but no warning is issued. Later on,
when the main binding is needed, it can't be found.
-- Neil
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2631>
GHC <http://www.haskell.org/ghc/>
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