diff options
Diffstat (limited to 'compiler/rename/RnEnv.lhs')
| -rw-r--r-- | compiler/rename/RnEnv.lhs | 21 |
1 files changed, 14 insertions, 7 deletions
diff --git a/compiler/rename/RnEnv.lhs b/compiler/rename/RnEnv.lhs index bdc2cdfe59..a89ab1f0a0 100644 --- a/compiler/rename/RnEnv.lhs +++ b/compiler/rename/RnEnv.lhs @@ -268,22 +268,29 @@ lookupExactOcc name ; return name } - (gre:_) -> return (gre_name gre) } + [gre] -> return (gre_name gre) + (gre:_) -> do {addErr dup_nm_err + ; return (gre_name gre) + } -- We can get more than one GRE here, if there are multiple - -- bindings for the same name; but there will already be a - -- reported error for the duplicate. (If we add the error - -- rather than stopping when we encounter it.) - -- So all we need do here is not crash. - -- Example is Trac #8932: + -- bindings for the same name. Sometimes they are catched later + -- by findLocalDupsRdrEnv, like in the this example (Trac #8932): -- $( [d| foo :: a->a; foo x = x |]) -- foo = True - -- Here the 'foo' in the splice turns into an Exact Name + -- But when the names are totally identical, we get panic (Trac #7241): + -- $(newName "Foo" >>= \o -> return [DataD [] o [] [RecC o []] [''Show]]) + -- So, lets emit error here, even if it will lead to two errors in some cases. + } where exact_nm_err = hang (ptext (sLit "The exact Name") <+> quotes (ppr name) <+> ptext (sLit "is not in scope")) 2 (vcat [ ptext (sLit "Probable cause: you used a unique Template Haskell name (NameU), ") , ptext (sLit "perhaps via newName, but did not bind it") , ptext (sLit "If that's it, then -ddump-splices might be useful") ]) + dup_nm_err = hang (ptext (sLit "Duplicate exact Name") <+> quotes (ppr $ nameOccName name)) + 2 (vcat [ ptext (sLit "Probable cause: you used a unique Template Haskell name (NameU), ") + , ptext (sLit "perhaps via newName, but bound it multiple times") + , ptext (sLit "If that's it, then -ddump-splices might be useful") ]) ----------------------------------------------- lookupInstDeclBndr :: Name -> SDoc -> RdrName -> RnM Name |