Fix Trac #3176: intercept naughty record selectors

When making record selectors into ordinary functions (rather than
magial implicit Ids) I forgot that they could therefore show up in
the *local* TcEnv, not the global one.  This fixes that problem,
and thereby Trac #3176.

diff --git a/compiler/typecheck/TcExpr.lhs b/compiler/typecheck/TcExpr.lhs
index 51d6f4b..b255fdb 100644 (file)
--- a/compiler/typecheck/TcExpr.lhs
+++ b/compiler/typecheck/TcExpr.lhs
@@ -1069,6 +1069,9 @@ lookupFun orig id_name
                -- nor does it need the 'lifting' treatment
 
            ATcId { tct_id = id, tct_type = ty, tct_co = mb_co, tct_level = lvl }
                -- nor does it need the 'lifting' treatment
 
            ATcId { tct_id = id, tct_type = ty, tct_co = mb_co, tct_level = lvl }

+               | isNaughtyRecordSelector id -> failWithTc (naughtyRecordSel id)
+                                         -- Note [Local record selectors]
+               | otherwise

                -> do { thLocalId orig id ty lvl
                      ; case mb_co of
                          Unrefineable    -> return (HsVar id, ty)
                -> do { thLocalId orig id ty lvl
                      ; case mb_co of
                          Unrefineable    -> return (HsVar id, ty)

@@ -1147,6 +1150,12 @@ thBrackId orig id ps_var lie_var
 #endif /* GHCI */
 \end{code}
 
 #endif /* GHCI */
 \end{code}
 

+Local record selectors
+~~~~~~~~~~~~~~~~~~~~~~
+Record selectors for TyCons in this module are ordinary local bindings,
+which show up as ATcIds rather than AGlobals.  So we need to check for
+naughtiness in both branches.  c.f. TcTyClsBindings.mkAuxBinds.
+

 
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