Servant-0.15 fails Core Lint
While reproducing #16918 (closed) with head.hackage I encountered the following, quite different looking, Core Lint failure:
*** Desugar [Servant.Types.SourceT]:
Desugar [Servant.Types.SourceT]: alloc=44631184 time=248.726
*** Simplifier [Servant.Types.SourceT]:
*** Core Lint errors : in result of Simplifier ***
<no location info>: warning:
In the expression: (case heq_sel
@ (* -> *)
@ (* -> *)
@ Identity
@ Identity
($d~_apms
`cast` (((~) <* -> *>_N <Identity>_N (Sym co_arYu))_R ; N:~[0]
<*
-> *>_N <Identity>_N <Identity>_N
:: (Identity ~ m_apmr) ~R# (Identity ~~ Identity)))
of co_Xs0P
{ __DEFAULT ->
\ (@ a_apof)
(@ b_apog)
(f_amLo :: a_apof -> b_apog -> b_apog)
(z_amLp :: b_apog)
(ds_dsPH :: SourceT Identity a_apof) ->
$cfoldr_ariD
@ Identity
($d~_apms
`cast` (((~) <* -> *>_N <Identity>_N (Sym co_arYu))_R
:: (Identity ~ m_apmr) ~R# (Identity ~ Identity)))
@ a_apof
@ b_apog
f_amLo
z_amLp
(((ds_dsPH
`cast` (N:SourceT[0] <Identity>_N <a_apof>_N
:: SourceT Identity a_apof
~R# (forall b.
(StepT Identity a_apof -> Identity b)
-> Identity b)))
@ (StepT Identity a_apof)
((\ (v_X2u :: StepT Identity a_apof) -> v_X2u)
`cast` (<StepT Identity a_apof>_R
->_R Sym (N:Identity[0] <StepT Identity a_apof>_R)
:: (StepT Identity a_apof -> StepT Identity a_apof)
~R# (StepT Identity a_apof
-> Identity (StepT Identity a_apof)))))
`cast` (N:Identity[0] <StepT Identity a_apof>_R
:: Identity (StepT Identity a_apof) ~R# StepT Identity a_apof))
})
@ a_aps3
@ b_asSG
c_asSH
n_asSI
(eta_B1
`cast` (Sym (SourceT co_arYu <a_aps3>_N)_R
:: SourceT m_apmr a_aps3 ~R# SourceT Identity a_aps3))
Type of case alternatives not the same as the annotation on case:
Actual type: forall a b.
(a -> b -> b) -> b -> SourceT Identity a -> b
Annotation on case: forall a b.
(a -> b -> b) -> b -> SourceT m_apmr a -> b
Alt Rhs: \ (@ a_apof)
(@ b_apog)
(f_amLo :: a_apof -> b_apog -> b_apog)
(z_amLp :: b_apog)
(ds_dsPH :: SourceT Identity a_apof) ->
$cfoldr_ariD
@ Identity
($d~_apms
`cast` (((~) <* -> *>_N <Identity>_N (Sym co_arYu))_R
:: (Identity ~ m_apmr) ~R# (Identity ~ Identity)))
@ a_apof
@ b_apog
f_amLo
z_amLp
(((ds_dsPH
`cast` (N:SourceT[0] <Identity>_N <a_apof>_N
:: SourceT Identity a_apof
~R# (forall b.
(StepT Identity a_apof -> Identity b) -> Identity b)))
@ (StepT Identity a_apof)
((\ (v_X2u :: StepT Identity a_apof) -> v_X2u)
`cast` (<StepT Identity a_apof>_R
->_R Sym (N:Identity[0] <StepT Identity a_apof>_R)
:: (StepT Identity a_apof -> StepT Identity a_apof)
~R# (StepT Identity a_apof
-> Identity (StepT Identity a_apof)))))
`cast` (N:Identity[0] <StepT Identity a_apof>_R
:: Identity (StepT Identity a_apof) ~R# StepT Identity a_apof))I believe the relevant binding is
$ctoList_aprW [InlPrag=INLINE (sat-args=1), Occ=LoopBreaker]
:: forall (m :: * -> *) a. (Identity ~ m) => SourceT m a -> [a]
[LclId,
Arity=2,
Unf=Unf{Src=InlineStable, TopLvl=True, Value=True, ConLike=True,
WorkFree=True, Expandable=True,
Guidance=ALWAYS_IF(arity=2,unsat_ok=False,boring_ok=False)
Tmpl= \ (@ (m_apmr :: * -> *)) ($d~_apms :: Identity ~ m_apmr) ->
case heq_sel
@ (* -> *)
@ (* -> *)
@ Identity
@ m_apmr
($d~_apms
`cast` (N:~[0] <* -> *>_N <Identity>_N <m_apmr>_N
:: (Identity ~ m_apmr) ~R# (Identity ~~ m_apmr)))
of co_arYu
{ __DEFAULT ->
\ (@ a_aps3) (t1_asSF [Occ=Once] :: SourceT m_apmr a_aps3) ->
build
@ a_aps3
(\ (@ b_asSG)
(c_asSH [Occ=Once, OS=OneShot] :: a_aps3 -> b_asSG -> b_asSG)
(n_asSI [Occ=Once, OS=OneShot] :: b_asSG) ->
(case heq_sel
@ (* -> *)
@ (* -> *)
@ Identity
@ Identity
($d~_apms
`cast` (((~) <* -> *>_N <Identity>_N (Sym co_arYu))_R ; N:~[0]
<*
-> *>_N <Identity>_N <Identity>_N
:: (Identity ~ m_apmr) ~R# (Identity ~~ Identity)))
of co_Xs0R
{ __DEFAULT ->
\ (@ a_apof)
(@ b_apog)
(f_amLo [Occ=Once, OS=OneShot] :: a_apof -> b_apog -> b_apog)
(z_amLp [Occ=Once, OS=OneShot] :: b_apog)
(ds_dsPH [Occ=Once, OS=OneShot] :: SourceT Identity a_apof) ->
$cfoldr_ariD
@ Identity
($d~_apms
`cast` (((~) <* -> *>_N <Identity>_N (Sym co_arYu))_R
:: (Identity ~ m_apmr) ~R# (Identity ~ Identity)))
@ a_apof
@ b_apog
f_amLo
z_amLp
(((ds_dsPH
`cast` (N:SourceT[0] <Identity>_N <a_apof>_N
:: SourceT Identity a_apof
~R# (forall b.
(StepT Identity a_apof -> Identity b)
-> Identity b)))
@ (StepT Identity a_apof)
((\ (v_B1 [Occ=Once] :: StepT Identity a_apof) -> v_B1)
`cast` (<StepT Identity a_apof>_R
->_R Sym (N:Identity[0] <StepT Identity a_apof>_R)
:: (StepT Identity a_apof -> StepT Identity a_apof)
~R# (StepT Identity a_apof
-> Identity (StepT Identity a_apof)))))
`cast` (N:Identity[0] <StepT Identity a_apof>_R
:: Identity (StepT Identity a_apof)
~R# StepT Identity a_apof))
})
@ a_aps3
@ b_asSG
c_asSH
n_asSI
(t1_asSF
`cast` (Sym (SourceT co_arYu <a_aps3>_N)_R
:: SourceT m_apmr a_aps3 ~R# SourceT Identity a_aps3)))
}}]