#5375: Regression in newName
---------------------------------+------------------------------------------
Reporter: reinerp | Owner:
Type: bug | Status: new
Priority: normal | Component: Template Haskell
Version: 7.3 | Keywords:
Testcase: | Blockedby:
Os: Unknown/Multiple | Blocking:
Architecture: Unknown/Multiple | Failure: GHC rejects valid program
---------------------------------+------------------------------------------
Template Haskell's {{{newName}}} no longer works properly, with GHC HEAD.
Consider:
{{{
{-# LANGUAGE TemplateHaskell #-}
module B where
import Language.Haskell.TH
data D = D
-- declare 'data E = D' with a fresh name 'D'
$(do
nm <- newName "D"
return $ [DataD [] (mkName "E") [] [NormalC nm []] []]
)
}}}
With {{{ghc-7.0.3}}}, this compiles without error, as it should. However,
with {{{ghc-7.3.20110803}}}, we get:
{{{
B.hs:8:3:
Multiple declarations of `D'
Declared at: B.hs:7:10
B.hs:8:3
}}}
which is wrong.
The following might also be related. Given:
{{{
{-# LANGUAGE TemplateHaskell #-}
module C where
import Language.Haskell.TH
g = $(do
nm <- newName "f"
return $ VarE nm
)
}}}
with {{{ghc-7.0.3}}} we get the correct error message
{{{
C.hs:7:7:
Not in scope: `f[aK5]'
In the result of the splice:
$(do { nm <- newName "f";
return $ VarE nm })
To see what the splice expanded to, use -ddump-splices
In the expression:
$(do { nm <- newName "f";
return $ VarE nm })
In an equation for `g':
g = $(do { nm <- newName "f";
return $ VarE nm })
}}}
but with {{{ghc-7.3.20110803}}} we get a GHC internal error message:
{{{
C.hs:7:7:
GHC internal error: `f_aOw' is not in scope during type checking, but
it passed the renamer
tcg_type_env of environment: []
tcl_env of environment: [(rgQ, Identifier[g::t_a, 1])]
In the expression: f_aOw
In the result of the splice:
$(do { nm <- newName "f";
return $ VarE nm })
To see what the splice expanded to, use -ddump-splices
In the expression:
$(do { nm <- newName "f";
return $ VarE nm })
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5375>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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