%
-% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996
+% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
\section[TcIfaceSig]{Type checking of type signatures in interface files}
\begin{code}
-#include "HsVersions.h"
-
-module TcIfaceSig ( tcInterfaceSigs ) where
+module TcIfaceSig ( tcInterfaceSigs, tcVar, tcCoreExpr, tcCoreLamBndrs ) where
-IMP_Ubiq()
+#include "HsVersions.h"
+import HsSyn ( HsDecl(..), TyClDecl(..), HsTupCon(..) )
import TcMonad
-import TcMonoType ( tcHsType, tcHsTypeKind )
-import TcEnv ( tcLookupGlobalValue, tcExtendTyVarEnv, tcExtendGlobalValEnv,
- tcLookupTyConByKey, tcLookupGlobalValueMaybe, tcLookupLocalValue
+import TcMonoType ( tcHsType )
+ -- NB: all the tyars in interface files are kinded,
+ -- so tcHsType will do the Right Thing without
+ -- having to mess about with zonking
+
+import TcEnv ( TcEnv, RecTcEnv, tcExtendTyVarEnv,
+ tcExtendGlobalValEnv, tcSetEnv,
+ tcLookupGlobal_maybe, tcLookupRecId, tcEnvIds
)
-import TcKind ( TcKind, kindToTcKind )
-import HsSyn ( IfaceSig(..), HsDecl(..), TyDecl, ClassDecl, InstDecl, DefaultDecl, HsBinds,
- Fake, InPat, HsType )
-import RnHsSyn ( RenamedHsDecl(..) )
+import RnHsSyn ( RenamedHsDecl )
import HsCore
-import HsDecls ( HsIdInfo(..) )
import Literal ( Literal(..) )
import CoreSyn
-import CoreUtils ( coreExprType )
+import CoreUtils ( exprType )
import CoreUnfold
-import MagicUFs ( MagicUnfoldingFun )
-import WwLib ( mkWrapper )
-import SpecEnv ( SpecEnv )
-import PrimOp ( PrimOp(..) )
-
-import Id ( GenId, mkImported, mkUserId, isPrimitiveId_maybe, dataConArgTys )
-import Type ( mkSynTy, getAppDataTyConExpandingDicts )
-import TyVar ( mkTyVar )
-import Name ( Name )
-import Unique ( rationalTyConKey )
-import TysWiredIn ( integerTy )
-import PragmaInfo ( PragmaInfo(..) )
-import ErrUtils ( pprBagOfErrors )
-import Maybes ( maybeToBool )
-import Pretty
-import PprStyle ( PprStyle(..) )
-import Util ( zipWithEqual, panic, pprTrace, pprPanic )
+import CoreLint ( lintUnfolding )
+import WorkWrap ( mkWrapper )
+import Id ( Id, mkId, mkVanillaId, isDataConWrapId_maybe )
+import MkId ( mkCCallOpId )
import IdInfo
+import DataCon ( dataConSig, dataConArgTys )
+import Type ( mkTyVarTys, splitAlgTyConApp_maybe )
+import Var ( mkTyVar, tyVarKind )
+import Name ( Name )
+import Demand ( wwLazy )
+import ErrUtils ( pprBagOfErrors )
+import Outputable
+import Util ( zipWithEqual )
+import HscTypes ( TyThing(..) )
\end{code}
Ultimately, type signatures in interfaces will have pragmatic
signatures.
\begin{code}
-tcInterfaceSigs :: [RenamedHsDecl] -> TcM s [Id]
- -- Ignore non-sig-decls in these decls
-
-tcInterfaceSigs (SigD (IfaceSig name ty id_infos src_loc) : rest)
- = tcAddSrcLoc src_loc $
- tcHsType ty `thenTc` \ sigma_ty ->
- tcIdInfo name sigma_ty noIdInfo id_infos `thenTc` \ id_info' ->
- let
- sig_id = mkImported name sigma_ty id_info'
- in
- tcInterfaceSigs rest `thenTc` \ sig_ids ->
- returnTc (sig_id : sig_ids)
-
-tcInterfaceSigs (other_decl : rest) = tcInterfaceSigs rest
-
-tcInterfaceSigs [] = returnTc []
+tcInterfaceSigs :: RecTcEnv -- Envt to use when checking unfoldings
+ -> [RenamedHsDecl] -- Ignore non-sig-decls in these decls
+ -> TcM [Id]
+
+
+tcInterfaceSigs unf_env decls
+ = listTc [ do_one name ty id_infos src_loc
+ | TyClD (IfaceSig name ty id_infos src_loc) <- decls]
+ where
+ in_scope_vars = [] -- I think this will be OK
+
+ do_one name ty id_infos src_loc
+ = tcAddSrcLoc src_loc $
+ tcAddErrCtxt (ifaceSigCtxt name) $
+ tcHsType ty `thenTc` \ sigma_ty ->
+ tcIdInfo unf_env in_scope_vars name
+ sigma_ty vanillaIdInfo id_infos `thenTc` \ id_info ->
+ returnTc (mkId name sigma_ty id_info)
\end{code}
\begin{code}
-tcIdInfo name ty info [] = returnTc info
-
-tcIdInfo name ty info (HsArity arity : rest)
- = tcIdInfo name ty (info `addArityInfo` arity) rest
-
-tcIdInfo name ty info (HsUpdate upd : rest)
- = tcIdInfo name ty (info `addUpdateInfo` upd) rest
-
-tcIdInfo name ty info (HsFBType fb : rest)
- = tcIdInfo name ty (info `addFBTypeInfo` fb) rest
-
-tcIdInfo name ty info (HsArgUsage au : rest)
- = tcIdInfo name ty (info `addArgUsageInfo` au) rest
-
-tcIdInfo name ty info (HsDeforest df : rest)
- = tcIdInfo name ty (info `addDeforestInfo` df) rest
-
-tcIdInfo name ty info (HsUnfold expr : rest)
- = tcUnfolding name expr `thenNF_Tc` \ unfold_info ->
- tcIdInfo name ty (info `addUnfoldInfo` unfold_info) rest
-
-tcIdInfo name ty info (HsStrictness strict : rest)
- = tcStrictness ty info strict `thenTc` \ info' ->
- tcIdInfo name ty info' rest
+tcIdInfo unf_env in_scope_vars name ty info info_ins
+ = foldlTc tcPrag constantIdInfo info_ins
+ where
+ tcPrag info (HsArity arity) = returnTc (info `setArityInfo` arity)
+ tcPrag info (HsNoCafRefs) = returnTc (info `setCafInfo` NoCafRefs)
+ tcPrag info HsCprInfo = returnTc (info `setCprInfo` ReturnsCPR)
+
+ tcPrag info (HsUnfold inline_prag expr)
+ = tcPragExpr unf_env name in_scope_vars expr `thenNF_Tc` \ maybe_expr' ->
+ let
+ -- maybe_expr doesn't get looked at if the unfolding
+ -- is never inspected; so the typecheck doesn't even happen
+ unfold_info = case maybe_expr' of
+ Nothing -> noUnfolding
+ Just expr' -> mkTopUnfolding expr'
+ info1 = info `setUnfoldingInfo` unfold_info
+ info2 = info1 `setInlinePragInfo` inline_prag
+ in
+ returnTc info2
+
+ tcPrag info (HsStrictness strict_info)
+ = returnTc (info `setStrictnessInfo` strict_info)
+
+ tcPrag info (HsWorker nm)
+ = tcWorkerInfo unf_env ty info nm
\end{code}
\begin{code}
-tcStrictness ty info (StrictnessInfo demands maybe_worker)
- = tcWorker maybe_worker `thenNF_Tc` \ maybe_worker_id ->
- uniqSMToTcM (mkWrapper ty demands) `thenNF_Tc` \ wrap_fn ->
+tcWorkerInfo unf_env ty info worker_name
+ | not (hasArity arity_info)
+ = pprPanic "Worker with no arity info" (ppr worker_name)
+
+ | otherwise
+ = uniqSMToTcM (mkWrapper ty arity demands res_bot cpr_info) `thenNF_Tc` \ wrap_fn ->
let
- -- Watch out! We can't pull on maybe_worker_id too eagerly!
- info' = case maybe_worker_id of
- Just worker_id -> info `addUnfoldInfo` mkUnfolding False (wrap_fn worker_id)
- Nothing -> info
- in
- returnTc (info' `addStrictnessInfo` StrictnessInfo demands maybe_worker_id)
-
--- Boring to write these out, but the result type differs from the arg type...
-tcStrictness ty info BottomGuaranteed
- = returnTc (info `addStrictnessInfo` BottomGuaranteed)
-tcStrictness ty info NoStrictnessInfo
- = returnTc info
-\end{code}
+ -- Watch out! We can't pull on unf_env too eagerly!
+ info' = case tcLookupRecId unf_env worker_name of
+ Just worker_id -> info `setUnfoldingInfo` mkTopUnfolding (wrap_fn worker_id)
+ `setWorkerInfo` HasWorker worker_id arity
-\begin{code}
-tcWorker Nothing = returnNF_Tc Nothing
-
-tcWorker (Just worker_name)
- = tcLookupGlobalValueMaybe worker_name `thenNF_Tc` \ maybe_worker_id ->
- returnNF_Tc (trace_maybe maybe_worker_id)
+ Nothing -> pprTrace "tcWorkerInfo failed:" (ppr worker_name) info
+ in
+ returnTc info'
where
- -- The trace is so we can see what's getting dropped
- trace_maybe Nothing = pprTrace "tcWorker failed:" (ppr PprDebug worker_name) Nothing
- trace_maybe (Just x) = Just x
+ -- We are relying here on arity, cpr and strictness info always appearing
+ -- before worker info, fingers crossed ....
+ arity_info = arityInfo info
+ arity = arityLowerBound arity_info
+ cpr_info = cprInfo info
+ (demands, res_bot) = case strictnessInfo info of
+ StrictnessInfo d r -> (d,r)
+ _ -> (take arity (repeat wwLazy),False) -- Noncommittal
\end{code}
For unfoldings we try to do the job lazily, so that we never type check
an unfolding that isn't going to be looked at.
\begin{code}
-tcUnfolding name core_expr
+tcPragExpr unf_env name in_scope_vars expr
+ = tcDelay unf_env doc $
+ tcCoreExpr expr `thenTc` \ core_expr' ->
+
+ -- Check for type consistency in the unfolding
+ tcGetSrcLoc `thenNF_Tc` \ src_loc ->
+ getDOptsTc `thenTc` \ dflags ->
+ case lintUnfolding dflags src_loc in_scope_vars core_expr' of
+ (Nothing,_) -> returnTc core_expr' -- ignore warnings
+ (Just fail_msg,_) -> failWithTc ((doc <+> text "failed Lint") $$ fail_msg)
+ where
+ doc = text "unfolding of" <+> ppr name
+
+tcDelay :: RecTcEnv -> SDoc -> TcM a -> NF_TcM (Maybe a)
+tcDelay unf_env doc thing_inside
= forkNF_Tc (
- recoverNF_Tc no_unfolding (
- tcCoreExpr core_expr `thenTc` \ core_expr' ->
- returnTc (mkUnfolding False core_expr')
+ recoverNF_Tc bad_value (
+ tcSetEnv unf_env thing_inside `thenTc` \ r ->
+ returnTc (Just r)
))
where
-- The trace tells what wasn't available, for the benefit of
-- compiler hackers who want to improve it!
- no_unfolding = getErrsTc `thenNF_Tc` \ (warns,errs) ->
- returnNF_Tc (pprTrace "tcUnfolding failed with:"
- (ppHang (ppr PprDebug name) 4 (pprBagOfErrors PprDebug errs))
- NoUnfolding)
+ bad_value = getErrsTc `thenNF_Tc` \ (warns,errs) ->
+ returnNF_Tc (pprTrace "Failed:"
+ (hang doc 4 (pprBagOfErrors errs))
+ Nothing)
\end{code}
****** Why? Because we know all the types and want to bind them to real Ids.
\begin{code}
-tcVar :: Name -> TcM s Id
+tcVar :: Name -> TcM Id
tcVar name
- = tcLookupGlobalValueMaybe name `thenNF_Tc` \ maybe_id ->
+ = tcLookupGlobal_maybe name `thenNF_Tc` \ maybe_id ->
case maybe_id of {
- Just id -> returnTc id;
- Nothing -> failTc (noDecl name)
+ Just (AnId id) -> returnTc id;
+ Nothing -> failWithTc (noDecl name)
}
-noDecl name sty = ppCat [ppPStr SLIT("Warning: no binding for"), ppr sty name]
+noDecl name = hsep [ptext SLIT("Warning: no binding for"), ppr name]
\end{code}
UfCore expressions.
\begin{code}
-tcCoreExpr :: UfExpr Name -> TcM s CoreExpr
+tcCoreExpr :: UfExpr Name -> TcM CoreExpr
+
+tcCoreExpr (UfType ty)
+ = tcHsType ty `thenTc` \ ty' ->
+ -- It might not be of kind type
+ returnTc (Type ty')
tcCoreExpr (UfVar name)
= tcVar name `thenTc` \ id ->
returnTc (Var id)
--- rationalTy isn't built in so we have to construct it
--- (the "ty" part of the incoming literal is simply bottom)
-tcCoreExpr (UfLit (NoRepRational lit _))
- = tcLookupTyConByKey rationalTyConKey `thenNF_Tc` \ rational_tycon ->
- let
- rational_ty = mkSynTy rational_tycon []
- in
- returnTc (Lit (NoRepRational lit rational_ty))
+tcCoreExpr (UfLit lit)
+ = returnTc (Lit lit)
--- Similarly for integers, except that it is wired in
-tcCoreExpr (UfLit (NoRepInteger lit _))
- = returnTc (Lit (NoRepInteger lit integerTy))
+-- The dreaded lit-lits are also similar, except here the type
+-- is read in explicitly rather than being implicit
+tcCoreExpr (UfLitLit lit ty)
+ = tcHsType ty `thenTc` \ ty' ->
+ returnTc (Lit (MachLitLit lit ty'))
-tcCoreExpr (UfLit other_lit)
- = returnTc (Lit other_lit)
+tcCoreExpr (UfCCall cc ty)
+ = tcHsType ty `thenTc` \ ty' ->
+ tcGetUnique `thenNF_Tc` \ u ->
+ returnTc (Var (mkCCallOpId u cc ty'))
-tcCoreExpr (UfCon con args)
- = tcVar con `thenTc` \ con_id ->
- mapTc tcCoreArg args `thenTc` \ args' ->
- returnTc (Con con_id args')
+tcCoreExpr (UfTuple (HsTupCon name _) args)
+ = tcVar name `thenTc` \ con_id ->
+ mapTc tcCoreExpr args `thenTc` \ args' ->
+ let
+ -- Put the missing type arguments back in
+ con_args = map (Type . exprType) args' ++ args'
+ in
+ returnTc (mkApps (Var con_id) con_args)
-tcCoreExpr (UfPrim prim args)
- = tcCorePrim prim `thenTc` \ primop ->
- mapTc tcCoreArg args `thenTc` \ args' ->
- returnTc (Prim primop args')
+tcCoreExpr (UfLam bndr body)
+ = tcCoreLamBndr bndr $ \ bndr' ->
+ tcCoreExpr body `thenTc` \ body' ->
+ returnTc (Lam bndr' body')
tcCoreExpr (UfApp fun arg)
= tcCoreExpr fun `thenTc` \ fun' ->
- tcCoreArg arg `thenTc` \ arg' ->
+ tcCoreExpr arg `thenTc` \ arg' ->
returnTc (App fun' arg')
-tcCoreExpr (UfCase scrut alts)
- = tcCoreExpr scrut `thenTc` \ scrut' ->
- tcCoreAlts (coreExprType scrut') alts `thenTc` \ alts' ->
- returnTc (Case scrut' alts')
-
-tcCoreExpr (UfSCC cc expr)
- = tcCoreExpr expr `thenTc` \ expr' ->
- returnTc (SCC cc expr')
-
-tcCoreExpr(UfCoerce coercion ty body)
- = tcCoercion coercion `thenTc` \ coercion' ->
- tcHsTypeKind ty `thenTc` \ (_,ty') ->
- tcCoreExpr body `thenTc` \ body' ->
- returnTc (Coerce coercion' ty' body')
-
-tcCoreExpr (UfLam bndr body)
- = tcCoreLamBndr bndr $ \ bndr' ->
- tcCoreExpr body `thenTc` \ body' ->
- returnTc (Lam bndr' body')
+tcCoreExpr (UfCase scrut case_bndr alts)
+ = tcCoreExpr scrut `thenTc` \ scrut' ->
+ let
+ scrut_ty = exprType scrut'
+ case_bndr' = mkVanillaId case_bndr scrut_ty
+ in
+ tcExtendGlobalValEnv [case_bndr'] $
+ mapTc (tcCoreAlt scrut_ty) alts `thenTc` \ alts' ->
+ returnTc (Case scrut' case_bndr' alts')
tcCoreExpr (UfLet (UfNonRec bndr rhs) body)
= tcCoreExpr rhs `thenTc` \ rhs' ->
returnTc (Let (Rec (bndrs' `zip` rhss')) body')
where
(bndrs, rhss) = unzip pairs
+
+tcCoreExpr (UfNote note expr)
+ = tcCoreExpr expr `thenTc` \ expr' ->
+ case note of
+ UfCoerce to_ty -> tcHsType to_ty `thenTc` \ to_ty' ->
+ returnTc (Note (Coerce to_ty'
+ (exprType expr')) expr')
+ UfInlineCall -> returnTc (Note InlineCall expr')
+ UfInlineMe -> returnTc (Note InlineMe expr')
+ UfSCC cc -> returnTc (Note (SCC cc) expr')
\end{code}
\begin{code}
tcCoreLamBndr (UfValBinder name ty) thing_inside
= tcHsType ty `thenTc` \ ty' ->
let
- id = mkUserId name ty' NoPragmaInfo
+ id = mkVanillaId name ty'
in
tcExtendGlobalValEnv [id] $
- thing_inside (ValBinder id)
+ thing_inside id
tcCoreLamBndr (UfTyBinder name kind) thing_inside
= let
tyvar = mkTyVar name kind
in
- tcExtendTyVarEnv [name] [(kindToTcKind kind, tyvar)] $
- thing_inside (TyBinder tyvar)
+ tcExtendTyVarEnv [tyvar] (thing_inside tyvar)
-tcCoreLamBndr (UfUsageBinder name) thing_inside
- = error "tcCoreLamBndr: usage"
+tcCoreLamBndrs [] thing_inside = thing_inside []
+tcCoreLamBndrs (b:bs) thing_inside
+ = tcCoreLamBndr b $ \ b' ->
+ tcCoreLamBndrs bs $ \ bs' ->
+ thing_inside (b':bs')
tcCoreValBndr (UfValBinder name ty) thing_inside
= tcHsType ty `thenTc` \ ty' ->
let
- id = mk_id name ty'
+ id = mkVanillaId name ty'
in
tcExtendGlobalValEnv [id] $
thing_inside id
tcCoreValBndrs bndrs thing_inside -- Expect them all to be ValBinders
= mapTc tcHsType tys `thenTc` \ tys' ->
let
- ids = zipWithEqual "tcCoreValBndr" mk_id names tys'
+ ids = zipWithEqual "tcCoreValBndr" mkVanillaId names tys'
in
tcExtendGlobalValEnv ids $
thing_inside ids
where
- names = map (\ (UfValBinder name _) -> name) bndrs
- tys = map (\ (UfValBinder _ ty) -> ty) bndrs
-
-mk_id name ty = mkUserId name ty NoPragmaInfo
+ names = [name | UfValBinder name _ <- bndrs]
+ tys = [ty | UfValBinder _ ty <- bndrs]
\end{code}
\begin{code}
-tcCoreArg (UfVarArg v) = tcVar v `thenTc` \ v' -> returnTc (VarArg v')
-tcCoreArg (UfTyArg ty) = tcHsTypeKind ty `thenTc` \ (_,ty') -> returnTc (TyArg ty')
-tcCoreArg (UfLitArg lit) = returnTc (LitArg lit)
-tcCoreArg (UfUsageArg u) = error "tcCoreArg: usage"
-
-tcCoreAlts scrut_ty (UfAlgAlts alts deflt)
- = mapTc tc_alt alts `thenTc` \ alts' ->
- tcCoreDefault scrut_ty deflt `thenTc` \ deflt' ->
- returnTc (AlgAlts alts' deflt')
- where
- tc_alt (con, names, rhs)
- = tcVar con `thenTc` \ con' ->
- let
- arg_tys = dataConArgTys con' inst_tys
- (tycon, inst_tys, cons) = getAppDataTyConExpandingDicts scrut_ty
- arg_ids = zipWithEqual "tcCoreAlts" mk_id names arg_tys
- in
- tcExtendGlobalValEnv arg_ids $
- tcCoreExpr rhs `thenTc` \ rhs' ->
- returnTc (con', arg_ids, rhs')
-
-tcCoreAlts scrut_ty (UfPrimAlts alts deflt)
- = mapTc tc_alt alts `thenTc` \ alts' ->
- tcCoreDefault scrut_ty deflt `thenTc` \ deflt' ->
- returnTc (PrimAlts alts' deflt')
- where
- tc_alt (lit, rhs) = tcCoreExpr rhs `thenTc` \ rhs' ->
- returnTc (lit, rhs')
-
-tcCoreDefault scrut_ty UfNoDefault = returnTc NoDefault
-tcCoreDefault scrut_ty (UfBindDefault name rhs)
- = let
- deflt_id = mk_id name scrut_ty
+tcCoreAlt scrut_ty (UfDefault, names, rhs)
+ = ASSERT( null names )
+ tcCoreExpr rhs `thenTc` \ rhs' ->
+ returnTc (DEFAULT, [], rhs')
+
+tcCoreAlt scrut_ty (UfLitAlt lit, names, rhs)
+ = ASSERT( null names )
+ tcCoreExpr rhs `thenTc` \ rhs' ->
+ returnTc (LitAlt lit, [], rhs')
+
+tcCoreAlt scrut_ty (UfLitLitAlt str ty, names, rhs)
+ = ASSERT( null names )
+ tcCoreExpr rhs `thenTc` \ rhs' ->
+ tcHsType ty `thenTc` \ ty' ->
+ returnTc (LitAlt (MachLitLit str ty'), [], rhs')
+
+-- A case alternative is made quite a bit more complicated
+-- by the fact that we omit type annotations because we can
+-- work them out. True enough, but its not that easy!
+tcCoreAlt scrut_ty alt@(UfDataAlt con_name, names, rhs)
+ = tcVar con_name `thenTc` \ con_id ->
+ let
+ con = case isDataConWrapId_maybe con_id of
+ Just con -> con
+ Nothing -> pprPanic "tcCoreAlt" (ppr con_id)
+
+ (main_tyvars, _, ex_tyvars, _, _, _) = dataConSig con
+
+ (_, inst_tys, cons) = case splitAlgTyConApp_maybe scrut_ty of
+ Just stuff -> stuff
+ Nothing -> pprPanic "tcCoreAlt" (ppr alt)
+ ex_tyvars' = [mkTyVar name (tyVarKind tv) | (name,tv) <- names `zip` ex_tyvars]
+ ex_tys' = mkTyVarTys ex_tyvars'
+ arg_tys = dataConArgTys con (inst_tys ++ ex_tys')
+ id_names = drop (length ex_tyvars) names
+ arg_ids
+#ifdef DEBUG
+ | length id_names /= length arg_tys
+ = pprPanic "tcCoreAlts" (ppr (con_name, names, rhs) $$
+ (ppr main_tyvars <+> ppr ex_tyvars) $$
+ ppr arg_tys)
+ | otherwise
+#endif
+ = zipWithEqual "tcCoreAlts" mkVanillaId id_names arg_tys
in
- tcExtendGlobalValEnv [deflt_id] $
- tcCoreExpr rhs `thenTc` \ rhs' ->
- returnTc (BindDefault deflt_id rhs')
-
-
-tcCoercion (UfIn n) = tcVar n `thenTc` \ n' -> returnTc (CoerceIn n')
-tcCoercion (UfOut n) = tcVar n `thenTc` \ n' -> returnTc (CoerceOut n')
-
-tcCorePrim (UfOtherOp op)
- = tcVar op `thenTc` \ op_id ->
- case isPrimitiveId_maybe op_id of
- Just prim_op -> returnTc prim_op
- Nothing -> pprPanic "tcCorePrim" (ppr PprDebug op_id)
-
-tcCorePrim (UfCCallOp str casm gc arg_tys res_ty)
- = mapTc tcHsType arg_tys `thenTc` \ arg_tys' ->
- tcHsType res_ty `thenTc` \ res_ty' ->
- returnTc (CCallOp str casm gc arg_tys' res_ty')
+ ASSERT( con `elem` cons && length inst_tys == length main_tyvars )
+ tcExtendTyVarEnv ex_tyvars' $
+ tcExtendGlobalValEnv arg_ids $
+ tcCoreExpr rhs `thenTc` \ rhs' ->
+ returnTc (DataAlt con, ex_tyvars' ++ arg_ids, rhs')
\end{code}
+\begin{code}
+ifaceSigCtxt sig_name
+ = hsep [ptext SLIT("In an interface-file signature for"), ppr sig_name]
+\end{code}