Two new warnings: arity differing from demand type, and strict IDs at top level

[ghc-hetmet.git] / compiler / basicTypes / Id.lhs

diff --git a/compiler/basicTypes/Id.lhs b/compiler/basicTypes/Id.lhs
index 549a58b..61a39f1 100644 (file)
--- a/compiler/basicTypes/Id.lhs
+++ b/compiler/basicTypes/Id.lhs
@@ -25,7 +25,7 @@ module Id (
        zapLamIdInfo, zapDemandIdInfo, zapFragileIdInfo,
 
        -- Predicates
-       isImplicitId, isDeadBinder, isDictId,
+       isImplicitId, isDeadBinder, isDictId, isStrictId,
        isExportedId, isLocalId, isGlobalId,
        isRecordSelector, isNaughtyRecordSelector,
        isClassOpId_maybe,
@@ -368,6 +368,20 @@ setIdNewStrictness id sig = modifyIdInfo (`setNewStrictnessInfo` Just sig) id
 
 zapIdNewStrictness :: Id -> Id
 zapIdNewStrictness id = modifyIdInfo (`setNewStrictnessInfo` Nothing) id
+\end{code}
+
+This predicate says whether the id has a strict demand placed on it or
+has a type such that it can always be evaluated strictly (e.g., an
+unlifted type, but see the comment for isStrictType).  We need to
+check separately whether <id> has a so-called "strict type" because if
+the demand for <id> hasn't been computed yet but <id> has a strict
+type, we still want (isStrictId <id>) to be True.
+\begin{code}
+isStrictId :: Id -> Bool
+isStrictId id
+  = ASSERT2( isId id, text "isStrictId: not an id: " <+> ppr id )
+           (isStrictDmd (idNewDemandInfo id)) || 
+           (isStrictType (idType id))
 
        ---------------------------------
        -- WORKER ID