Commit 81e41fe3 authored by's avatar
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Rule binders shouldn't have DFun pragmas

When DsBinds deals with a SPECIALISE pragma, it makes up the binders
for a RULE. These binders should be very vanilla: no IdInfo of any sort.
But the way it was before they could have DFun pragmas, which led to
Bad Joss downstream.  (Actually to cause a downstream *error* was itself
a bug, which I've fixed, but it's clearly wrong for them to be DFuns!)
parent 6e335238
......@@ -38,6 +38,7 @@ import TysPrim ( anyTypeOfKind )
import CostCentre
import Module
import Id
import Name ( localiseName )
import MkId ( seqId )
import Var ( Var, TyVar, tyVarKind )
import IdInfo ( vanillaIdInfo )
......@@ -482,10 +483,10 @@ dsSpecs poly_id poly_rhs prags
-- Get the INLINE pragma from SPECIALISE declaration, or,
-- failing that, from the original Id
extra_dict_bndrs = [ localiseId d -- See Note [Constant rule dicts]
extra_dict_bndrs = [ mkLocalId (localiseName (idName d)) (idType d)
-- See Note [Constant rule dicts]
| d <- varSetElems (exprFreeVars ds_spec_expr)
, isDictId d]
-- Note [Const rule dicts]
rule = mkLocalRule (mkFastString ("SPEC " ++ showSDoc (ppr poly_name)))
AlwaysActive poly_name
......@@ -552,7 +553,7 @@ the constraint is unused. We could bind 'd' to (error "unused")
but it seems better to reject the program because it's almost certainly
a mistake. That's what the isDeadBinder call detects.
Note [Const rule dicts]
Note [Constant rule dicts]
When the LHS of a specialisation rule, (/\as\ds. f es) has a free dict,
which is presumably in scope at the function definition site, we can quantify
......@@ -573,8 +574,9 @@ And from that we want the rule
But be careful! That dInt might be GHC.Base.$fOrdInt, which is an External
Name, and you can't bind them in a lambda or forall without getting things
confused. Hence the use of 'localiseId' to make it Internal.
confused. Likewise it might have an InlineRule or something, which would be
utterly bogus. So we really make a fresh Id, with the same unique and type
as the old one, but with an Internal name and no IdInfo.
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