Implement cast worker/wrapper properly

The cast worker/wrapper transformation transforms
   x = e |> co
into
   y = e
   x = y |> co

This is done by the simplifier, but we were being
careless about transferring IdInfo from x to y,
and about what to do if x is a NOINLNE function.
This resulted in a series of bugs:
     #17673, #18093, #18078.

This patch fixes all that:

* Main change is in GHC.Core.Opt.Simplify, and
  the new prepareBinding function, which does this
  cast worker/wrapper transform.
  See Note [Cast worker/wrappers].

* There is quite a bit of refactoring around
  prepareRhs, makeTrivial etc.  It's nicer now.

* Some wrappers from strictness and cast w/w, notably those for
  a function with a NOINLINE, should inline very late. There
  wasn't really a mechanism for that, which was an existing bug
  really; so I invented a new finalPhase = Phase (-1).  It's used
  for all simplifier runs after the user-visible phase 2,1,0 have
  run.  (No new runs of the simplifier are introduced thereby.)

  See new Note [Compiler phases] in GHC.Types.Basic;
  the main changes are in GHC.Core.Opt.Driver

* Doing this made me trip over two places where the AnonArgFlag on a
  FunTy was being lost so we could end up with (Num a -> ty)
  rather than (Num a => ty)
    - In coercionLKind/coercionRKind
    - In contHoleType in the Simplifier

  I fixed the former by defining mkFunctionType and using it in
  coercionLKind/RKind.

  I could have done the same for the latter, but the information
  is almost to hand.  So I fixed the latter by
    - adding sc_hole_ty to ApplyToVal (like ApplyToTy),
    - adding as_hole_ty to ValArg (like TyArg)
    - adding sc_fun_ty to StrictArg
  Turned out I could then remove ai_type from ArgInfo.  This is
  just moving the deck chairs around, but it worked out nicely.

  See the new Note [AnonArgFlag] in GHC.Types.Var

* When looking at the 'arity decrease' thing (#18093) I discovered
  that stable unfoldings had a much lower arity than the actual
  optimised function.  That's what led to the arity-decrease
  message.  Simple solution: eta-expand.

  It's described in Note [Eta-expand stable unfoldings]
  in GHC.Core.Opt.Simplify

* I also discovered that unsafeCoerce wasn't being inlined if
  the context was boring.  So (\x. f (unsafeCoerce x)) would
  create a thunk -- yikes!  I fixed that by making inlineBoringOK
  a bit cleverer: see Note [Inline unsafeCoerce] in GHC.Core.Unfold.

  I also found that unsafeCoerceName was unused, so I removed it.

I made a test case for #18078, and a very similar one for #17673.

The net effect of all this on nofib is very modest, but positive:

--------------------------------------------------------------------------------
        Program           Size    Allocs   Runtime   Elapsed  TotalMem
--------------------------------------------------------------------------------
           anna          -0.4%     -0.1%     -3.1%     -3.1%      0.0%
 fannkuch-redux          -0.4%     -0.3%     -0.1%     -0.1%      0.0%
       maillist          -0.4%     -0.1%     -7.8%     -1.0%    -14.3%
      primetest          -0.4%    -15.6%     -7.1%     -6.6%      0.0%
--------------------------------------------------------------------------------
            Min          -0.9%    -15.6%    -13.3%    -14.2%    -14.3%
            Max          -0.3%      0.0%    +12.1%    +12.4%      0.0%
 Geometric Mean          -0.4%     -0.2%     -2.3%     -2.2%     -0.1%

All following metric decreases are compile-time allocation decreases
between -1% and -3%:

Metric Decrease:
  T5631
  T13701
  T14697
  T15164

13 files changed, 239 insertions, 8 deletions

diff --git a/testsuite/tests/codeGen/should_compile/debug.stdout b/testsuite/tests/codeGen/should_compile/debug.stdout
index 3dca62a419..25df0c258f 100644
--- a/testsuite/tests/codeGen/should_compile/debug.stdout
+++ b/testsuite/tests/codeGen/should_compile/debug.stdout
@@ -18,6 +18,7 @@ src<debug.hs:4:9>
 src<debug.hs:5:21-29>
 src<debug.hs:5:9-29>
 src<debug.hs:6:1-21>
+src<debug.hs:6:16-21>
 == CBE ==
 src<debug.hs:4:9>
 89
diff --git a/testsuite/tests/deSugar/should_compile/T2431.stderr b/testsuite/tests/deSugar/should_compile/T2431.stderr
index 08946c5cd3..c44c342f05 100644
--- a/testsuite/tests/deSugar/should_compile/T2431.stderr
+++ b/testsuite/tests/deSugar/should_compile/T2431.stderr
@@ -4,7 +4,7 @@ Result size of Tidy Core
   = {terms: 63, types: 43, coercions: 1, joins: 0/0}
 
 -- RHS size: {terms: 2, types: 4, coercions: 1, joins: 0/0}
-T2431.$WRefl [InlPrag=INLINE[0] CONLIKE] :: forall a. a :~: a
+T2431.$WRefl [InlPrag=INLINE[final] CONLIKE] :: forall a. a :~: a
 [GblId[DataConWrapper],
  Caf=NoCafRefs,
  Cpr=m1,
diff --git a/testsuite/tests/perf/compiler/T16473.stdout b/testsuite/tests/perf/compiler/T16473.stdout
index 2d14bc5fe7..755017fd83 100644
--- a/testsuite/tests/perf/compiler/T16473.stdout
+++ b/testsuite/tests/perf/compiler/T16473.stdout
@@ -1,10 +1,10 @@
 Rule fired: Class op fmap (BUILTIN)
 Rule fired: Class op liftA2 (BUILTIN)
-Rule fired: Class op $p1Applicative (BUILTIN)
 Rule fired: Class op <*> (BUILTIN)
-Rule fired: Class op <$ (BUILTIN)
 Rule fired: Class op $p1Applicative (BUILTIN)
+Rule fired: Class op <$ (BUILTIN)
 Rule fired: Class op <*> (BUILTIN)
+Rule fired: Class op $p1Applicative (BUILTIN)
 Rule fired: Class op fmap (BUILTIN)
 Rule fired: Class op pure (BUILTIN)
 Rule fired: Class op pure (BUILTIN)
diff --git a/testsuite/tests/simplCore/should_compile/T13143.stderr b/testsuite/tests/simplCore/should_compile/T13143.stderr
index 755d6b3639..a5610d8d3d 100644
--- a/testsuite/tests/simplCore/should_compile/T13143.stderr
+++ b/testsuite/tests/simplCore/should_compile/T13143.stderr
@@ -12,7 +12,7 @@ T13143.$wf = \ (@a) _ [Occ=Dead] -> T13143.$wf @a GHC.Prim.void#
 end Rec }
 
 -- RHS size: {terms: 4, types: 4, coercions: 0, joins: 0/0}
-f [InlPrag=NOUSERINLINE[0]] :: forall a. Int -> a
+f [InlPrag=NOUSERINLINE[final]] :: forall a. Int -> a
 [GblId,
  Arity=1,
  Str=<B,A>b,
diff --git a/testsuite/tests/simplCore/should_compile/T17673.hs b/testsuite/tests/simplCore/should_compile/T17673.hs
new file mode 100644
index 0000000000..37d8bea693
--- /dev/null
+++ b/testsuite/tests/simplCore/should_compile/T17673.hs
@@ -0,0 +1,6 @@
+module T17673 where
+
+facIO :: Int -> IO Int
+facIO n | n < 2     = return 1
+        | otherwise = do n' <- facIO (n-1); return (n*n')
+{-# NOINLINE facIO #-}
diff --git a/testsuite/tests/simplCore/should_compile/T17673.stderr b/testsuite/tests/simplCore/should_compile/T17673.stderr
new file mode 100644
index 0000000000..e3e993c8de
--- /dev/null
+++ b/testsuite/tests/simplCore/should_compile/T17673.stderr
@@ -0,0 +1,66 @@
+
+==================== Tidy Core ====================
+Result size of Tidy Core = {terms: 56, types: 67, coercions: 5, joins: 0/0}
+
+-- RHS size: {terms: 1, types: 0, coercions: 0, joins: 0/0}
+T17673.$trModule4 :: GHC.Prim.Addr#
+[GblId, Unf=Unf{Src=<vanilla>, TopLvl=True, Value=True, ConLike=True, WorkFree=True, Expandable=True, Guidance=IF_ARGS [] 20 0}]
+T17673.$trModule4 = "main"#
+
+-- RHS size: {terms: 2, types: 0, coercions: 0, joins: 0/0}
+T17673.$trModule3 :: GHC.Types.TrName
+[GblId, Unf=Unf{Src=<vanilla>, TopLvl=True, Value=True, ConLike=True, WorkFree=True, Expandable=True, Guidance=IF_ARGS [] 10 20}]
+T17673.$trModule3 = GHC.Types.TrNameS T17673.$trModule4
+
+-- RHS size: {terms: 1, types: 0, coercions: 0, joins: 0/0}
+T17673.$trModule2 :: GHC.Prim.Addr#
+[GblId, Unf=Unf{Src=<vanilla>, TopLvl=True, Value=True, ConLike=True, WorkFree=True, Expandable=True, Guidance=IF_ARGS [] 30 0}]
+T17673.$trModule2 = "T17673"#
+
+-- RHS size: {terms: 2, types: 0, coercions: 0, joins: 0/0}
+T17673.$trModule1 :: GHC.Types.TrName
+[GblId, Unf=Unf{Src=<vanilla>, TopLvl=True, Value=True, ConLike=True, WorkFree=True, Expandable=True, Guidance=IF_ARGS [] 10 20}]
+T17673.$trModule1 = GHC.Types.TrNameS T17673.$trModule2
+
+-- RHS size: {terms: 3, types: 0, coercions: 0, joins: 0/0}
+T17673.$trModule :: GHC.Types.Module
+[GblId, Unf=Unf{Src=<vanilla>, TopLvl=True, Value=True, ConLike=True, WorkFree=True, Expandable=True, Guidance=IF_ARGS [] 10 30}]
+T17673.$trModule = GHC.Types.Module T17673.$trModule3 T17673.$trModule1
+
+-- RHS size: {terms: 2, types: 0, coercions: 0, joins: 0/0}
+lvl :: Int
+[GblId, Unf=OtherCon []]
+lvl = GHC.Types.I# 1#
+
+Rec {
+-- RHS size: {terms: 27, types: 31, coercions: 0, joins: 0/0}
+T17673.$wfacIO [InlPrag=NOINLINE, Occ=LoopBreaker] :: GHC.Prim.Int# -> GHC.Prim.State# GHC.Prim.RealWorld -> (# GHC.Prim.State# GHC.Prim.RealWorld, Int #)
+[GblId, Arity=2, Str=<L,U><L,U>, Unf=OtherCon []]
+T17673.$wfacIO
+  = \ (ww :: GHC.Prim.Int#) (w :: GHC.Prim.State# GHC.Prim.RealWorld) ->
+      case GHC.Prim.<# ww 2# of {
+        __DEFAULT -> case T17673.$wfacIO (GHC.Prim.-# ww 1#) w of { (# ipv, ipv1 #) -> (# ipv, case ipv1 of { GHC.Types.I# y -> GHC.Types.I# (GHC.Prim.*# ww y) } #) };
+        1# -> (# w, lvl #)
+      }
+end Rec }
+
+-- RHS size: {terms: 8, types: 5, coercions: 0, joins: 0/0}
+T17673.facIO1 [InlPrag=NOUSERINLINE[-1]] :: Int -> GHC.Prim.State# GHC.Prim.RealWorld -> (# GHC.Prim.State# GHC.Prim.RealWorld, Int #)
+[GblId,
+ Arity=2,
+ Str=<S,1*U(U)><L,U>,
+ Unf=Unf{Src=InlineStable, TopLvl=True, Value=True, ConLike=True, WorkFree=True, Expandable=True, Guidance=ALWAYS_IF(arity=2,unsat_ok=True,boring_ok=False)
+         Tmpl= \ (w [Occ=Once!] :: Int) (w1 [Occ=Once] :: GHC.Prim.State# GHC.Prim.RealWorld) -> case w of { GHC.Types.I# ww1 [Occ=Once] -> T17673.$wfacIO ww1 w1 }}]
+T17673.facIO1 = \ (w :: Int) (w1 :: GHC.Prim.State# GHC.Prim.RealWorld) -> case w of { GHC.Types.I# ww1 -> T17673.$wfacIO ww1 w1 }
+
+-- RHS size: {terms: 1, types: 0, coercions: 5, joins: 0/0}
+facIO [InlPrag=NOUSERINLINE[-1]] :: Int -> IO Int
+[GblId,
+ Arity=2,
+ Str=<S,1*U(U)><L,U>,
+ Unf=Unf{Src=InlineStable, TopLvl=True, Value=True, ConLike=True, WorkFree=True, Expandable=True, Guidance=ALWAYS_IF(arity=0,unsat_ok=True,boring_ok=True)
+         Tmpl= T17673.facIO1 `cast` (<Int>_R ->_R Sym (GHC.Types.N:IO[0] <Int>_R) :: (Int -> GHC.Prim.State# GHC.Prim.RealWorld -> (# GHC.Prim.State# GHC.Prim.RealWorld, Int #)) ~R# (Int -> IO Int))}]
+facIO = T17673.facIO1 `cast` (<Int>_R ->_R Sym (GHC.Types.N:IO[0] <Int>_R) :: (Int -> GHC.Prim.State# GHC.Prim.RealWorld -> (# GHC.Prim.State# GHC.Prim.RealWorld, Int #)) ~R# (Int -> IO Int))
+
+
+
diff --git a/testsuite/tests/simplCore/should_compile/T18078.hs b/testsuite/tests/simplCore/should_compile/T18078.hs
new file mode 100644
index 0000000000..e28b4a98ac
--- /dev/null
+++ b/testsuite/tests/simplCore/should_compile/T18078.hs
@@ -0,0 +1,13 @@
+module T18078 where
+
+newtype N = N { unN :: Int -> Int }
+
+-- This an example of a worker/wrapper thing
+-- See Note [Cast worker/wrappers] in Simplify
+-- We should get good code, with a $wf calling itself
+-- but in 8.10 we do not
+f :: N
+{-# NOINLINE f #-}
+f = N (\n -> if n==0 then 0 else unN f (n-1))
+
+g x = unN f (x+1)
diff --git a/testsuite/tests/simplCore/should_compile/T18078.stderr b/testsuite/tests/simplCore/should_compile/T18078.stderr
new file mode 100644
index 0000000000..6f5fcdce8a
--- /dev/null
+++ b/testsuite/tests/simplCore/should_compile/T18078.stderr
@@ -0,0 +1,141 @@
+
+==================== Tidy Core ====================
+Result size of Tidy Core = {terms: 98, types: 40, coercions: 5, joins: 0/0}
+
+-- RHS size: {terms: 2, types: 1, coercions: 0, joins: 0/0}
+T18078.unN1 :: N -> N
+[GblId,
+ Arity=1,
+ Str=<S,1*U>,
+ Unf=Unf{Src=InlineStable, TopLvl=True, Value=True, ConLike=True, WorkFree=True, Expandable=True, Guidance=ALWAYS_IF(arity=1,unsat_ok=True,boring_ok=True)
+         Tmpl= \ (ds [Occ=Once] :: N) -> ds}]
+T18078.unN1 = \ (ds :: N) -> ds
+
+-- RHS size: {terms: 1, types: 0, coercions: 3, joins: 0/0}
+unN :: N -> Int -> Int
+[GblId[[RecSel]],
+ Arity=1,
+ Str=<S,1*U>,
+ Unf=Unf{Src=InlineStable, TopLvl=True, Value=True, ConLike=True, WorkFree=True, Expandable=True, Guidance=ALWAYS_IF(arity=0,unsat_ok=True,boring_ok=True)
+         Tmpl= T18078.unN1 `cast` (<N>_R ->_R T18078.N:N[0] :: (N -> N) ~R# (N -> Int -> Int))}]
+unN = T18078.unN1 `cast` (<N>_R ->_R T18078.N:N[0] :: (N -> N) ~R# (N -> Int -> Int))
+
+-- RHS size: {terms: 1, types: 0, coercions: 0, joins: 0/0}
+T18078.$trModule4 :: GHC.Prim.Addr#
+[GblId, Unf=Unf{Src=<vanilla>, TopLvl=True, Value=True, ConLike=True, WorkFree=True, Expandable=True, Guidance=IF_ARGS [] 20 0}]
+T18078.$trModule4 = "main"#
+
+-- RHS size: {terms: 2, types: 0, coercions: 0, joins: 0/0}
+T18078.$trModule3 :: GHC.Types.TrName
+[GblId, Unf=Unf{Src=<vanilla>, TopLvl=True, Value=True, ConLike=True, WorkFree=True, Expandable=True, Guidance=IF_ARGS [] 10 20}]
+T18078.$trModule3 = GHC.Types.TrNameS T18078.$trModule4
+
+-- RHS size: {terms: 1, types: 0, coercions: 0, joins: 0/0}
+T18078.$trModule2 :: GHC.Prim.Addr#
+[GblId, Unf=Unf{Src=<vanilla>, TopLvl=True, Value=True, ConLike=True, WorkFree=True, Expandable=True, Guidance=IF_ARGS [] 30 0}]
+T18078.$trModule2 = "T18078"#
+
+-- RHS size: {terms: 2, types: 0, coercions: 0, joins: 0/0}
+T18078.$trModule1 :: GHC.Types.TrName
+[GblId, Unf=Unf{Src=<vanilla>, TopLvl=True, Value=True, ConLike=True, WorkFree=True, Expandable=True, Guidance=IF_ARGS [] 10 20}]
+T18078.$trModule1 = GHC.Types.TrNameS T18078.$trModule2
+
+-- RHS size: {terms: 3, types: 0, coercions: 0, joins: 0/0}
+T18078.$trModule :: GHC.Types.Module
+[GblId, Unf=Unf{Src=<vanilla>, TopLvl=True, Value=True, ConLike=True, WorkFree=True, Expandable=True, Guidance=IF_ARGS [] 10 30}]
+T18078.$trModule = GHC.Types.Module T18078.$trModule3 T18078.$trModule1
+
+-- RHS size: {terms: 3, types: 1, coercions: 0, joins: 0/0}
+$krep :: GHC.Types.KindRep
+[GblId, Cpr=m1, Unf=OtherCon []]
+$krep = GHC.Types.KindRepTyConApp GHC.Types.$tcInt (GHC.Types.[] @GHC.Types.KindRep)
+
+-- RHS size: {terms: 3, types: 0, coercions: 0, joins: 0/0}
+$krep1 :: GHC.Types.KindRep
+[GblId, Cpr=m4, Unf=OtherCon []]
+$krep1 = GHC.Types.KindRepFun $krep $krep
+
+-- RHS size: {terms: 1, types: 0, coercions: 0, joins: 0/0}
+T18078.$tcN2 :: GHC.Prim.Addr#
+[GblId, Unf=Unf{Src=<vanilla>, TopLvl=True, Value=True, ConLike=True, WorkFree=True, Expandable=True, Guidance=IF_ARGS [] 20 0}]
+T18078.$tcN2 = "N"#
+
+-- RHS size: {terms: 2, types: 0, coercions: 0, joins: 0/0}
+T18078.$tcN1 :: GHC.Types.TrName
+[GblId, Unf=Unf{Src=<vanilla>, TopLvl=True, Value=True, ConLike=True, WorkFree=True, Expandable=True, Guidance=IF_ARGS [] 10 20}]
+T18078.$tcN1 = GHC.Types.TrNameS T18078.$tcN2
+
+-- RHS size: {terms: 7, types: 0, coercions: 0, joins: 0/0}
+T18078.$tcN :: GHC.Types.TyCon
+[GblId, Unf=Unf{Src=<vanilla>, TopLvl=True, Value=True, ConLike=True, WorkFree=True, Expandable=True, Guidance=IF_ARGS [] 10 70}]
+T18078.$tcN = GHC.Types.TyCon 8242209344145137716## 16993518540698548720## T18078.$trModule T18078.$tcN1 0# GHC.Types.krep$*
+
+-- RHS size: {terms: 3, types: 1, coercions: 0, joins: 0/0}
+$krep2 :: GHC.Types.KindRep
+[GblId, Cpr=m1, Unf=OtherCon []]
+$krep2 = GHC.Types.KindRepTyConApp T18078.$tcN (GHC.Types.[] @GHC.Types.KindRep)
+
+-- RHS size: {terms: 3, types: 0, coercions: 0, joins: 0/0}
+T18078.$tc'N1 [InlPrag=NOUSERINLINE[~]] :: GHC.Types.KindRep
+[GblId, Cpr=m4, Unf=OtherCon []]
+T18078.$tc'N1 = GHC.Types.KindRepFun $krep1 $krep2
+
+-- RHS size: {terms: 1, types: 0, coercions: 0, joins: 0/0}
+T18078.$tc'N3 :: GHC.Prim.Addr#
+[GblId, Unf=Unf{Src=<vanilla>, TopLvl=True, Value=True, ConLike=True, WorkFree=True, Expandable=True, Guidance=IF_ARGS [] 20 0}]
+T18078.$tc'N3 = "'N"#
+
+-- RHS size: {terms: 2, types: 0, coercions: 0, joins: 0/0}
+T18078.$tc'N2 :: GHC.Types.TrName
+[GblId, Unf=Unf{Src=<vanilla>, TopLvl=True, Value=True, ConLike=True, WorkFree=True, Expandable=True, Guidance=IF_ARGS [] 10 20}]
+T18078.$tc'N2 = GHC.Types.TrNameS T18078.$tc'N3
+
+-- RHS size: {terms: 7, types: 0, coercions: 0, joins: 0/0}
+T18078.$tc'N :: GHC.Types.TyCon
+[GblId, Unf=Unf{Src=<vanilla>, TopLvl=True, Value=True, ConLike=True, WorkFree=True, Expandable=True, Guidance=IF_ARGS [] 10 70}]
+T18078.$tc'N = GHC.Types.TyCon 15484649745433776318## 6635095266531093649## T18078.$trModule T18078.$tc'N2 0# T18078.$tc'N1
+
+Rec {
+-- RHS size: {terms: 10, types: 2, coercions: 0, joins: 0/0}
+T18078.$wf [InlPrag=NOINLINE, Occ=LoopBreaker] :: GHC.Prim.Int# -> GHC.Prim.Int#
+[GblId, Arity=1, Str=<S,1*U>, Unf=OtherCon []]
+T18078.$wf
+  = \ (ww :: GHC.Prim.Int#) ->
+      case ww of wild {
+        __DEFAULT -> T18078.$wf (GHC.Prim.-# wild 1#);
+        0# -> 0#
+      }
+end Rec }
+
+-- RHS size: {terms: 10, types: 4, coercions: 0, joins: 0/0}
+T18078.f1 [InlPrag=NOUSERINLINE[-1]] :: Int -> Int
+[GblId,
+ Arity=1,
+ Str=<S(S),1*U(1*U)>,
+ Cpr=m1,
+ Unf=Unf{Src=InlineStable, TopLvl=True, Value=True, ConLike=True, WorkFree=True, Expandable=True, Guidance=ALWAYS_IF(arity=1,unsat_ok=True,boring_ok=False)
+         Tmpl= \ (w [Occ=Once!] :: Int) -> case w of { GHC.Types.I# ww1 [Occ=Once] -> case T18078.$wf ww1 of ww2 [Occ=Once] { __DEFAULT -> GHC.Types.I# ww2 } }}]
+T18078.f1 = \ (w :: Int) -> case w of { GHC.Types.I# ww1 -> case T18078.$wf ww1 of ww2 { __DEFAULT -> GHC.Types.I# ww2 } }
+
+-- RHS size: {terms: 1, types: 0, coercions: 2, joins: 0/0}
+f [InlPrag=NOUSERINLINE[-1]] :: N
+[GblId,
+ Arity=1,
+ Str=<S(S),1*U(1*U)>,
+ Cpr=m1,
+ Unf=Unf{Src=InlineStable, TopLvl=True, Value=True, ConLike=True, WorkFree=True, Expandable=True, Guidance=ALWAYS_IF(arity=0,unsat_ok=True,boring_ok=True)
+         Tmpl= T18078.f1 `cast` (Sym (T18078.N:N[0]) :: (Int -> Int) ~R# N)}]
+f = T18078.f1 `cast` (Sym (T18078.N:N[0]) :: (Int -> Int) ~R# N)
+
+-- RHS size: {terms: 12, types: 4, coercions: 0, joins: 0/0}
+g :: Int -> Int
+[GblId,
+ Arity=1,
+ Str=<S,1*U(U)>,
+ Cpr=m1,
+ Unf=Unf{Src=InlineStable, TopLvl=True, Value=True, ConLike=True, WorkFree=True, Expandable=True, Guidance=ALWAYS_IF(arity=1,unsat_ok=True,boring_ok=False)
+         Tmpl= \ (x [Occ=Once!] :: Int) -> case x of { GHC.Types.I# x1 [Occ=Once] -> T18078.f1 (GHC.Types.I# (GHC.Prim.+# x1 1#)) }}]
+g = \ (x :: Int) -> case x of { GHC.Types.I# x1 -> case T18078.$wf (GHC.Prim.+# x1 1#) of ww { __DEFAULT -> GHC.Types.I# ww } }
+
+
+
diff --git a/testsuite/tests/simplCore/should_compile/T3772.stdout b/testsuite/tests/simplCore/should_compile/T3772.stdout
index e2d90988e3..4a90b9f516 100644
--- a/testsuite/tests/simplCore/should_compile/T3772.stdout
+++ b/testsuite/tests/simplCore/should_compile/T3772.stdout
@@ -62,7 +62,7 @@ T3772.$wfoo
       }
 
 -- RHS size: {terms: 6, types: 3, coercions: 0, joins: 0/0}
-foo [InlPrag=NOUSERINLINE[0]] :: Int -> ()
+foo [InlPrag=NOUSERINLINE[final]] :: Int -> ()
 [GblId,
  Arity=1,
  Str=<S,1*U(U)>,
diff --git a/testsuite/tests/simplCore/should_compile/T7360.stderr b/testsuite/tests/simplCore/should_compile/T7360.stderr
index fa7f1e80ad..9caaa16ff1 100644
--- a/testsuite/tests/simplCore/should_compile/T7360.stderr
+++ b/testsuite/tests/simplCore/should_compile/T7360.stderr
@@ -4,7 +4,7 @@ Result size of Tidy Core
   = {terms: 106, types: 47, coercions: 0, joins: 0/0}
 
 -- RHS size: {terms: 6, types: 3, coercions: 0, joins: 0/0}
-T7360.$WFoo3 [InlPrag=INLINE[0] CONLIKE] :: Int -> Foo
+T7360.$WFoo3 [InlPrag=INLINE[final] CONLIKE] :: Int -> Foo
 [GblId[DataConWrapper],
  Arity=1,
  Caf=NoCafRefs,
diff --git a/testsuite/tests/simplCore/should_compile/T7865.stdout b/testsuite/tests/simplCore/should_compile/T7865.stdout
index 4073fec7ad..7c5d779425 100644
--- a/testsuite/tests/simplCore/should_compile/T7865.stdout
+++ b/testsuite/tests/simplCore/should_compile/T7865.stdout
@@ -1,6 +1,6 @@
 T7865.$wexpensive [InlPrag=NOINLINE]
 T7865.$wexpensive
-expensive [InlPrag=NOUSERINLINE[0]] :: Int -> Int
+expensive [InlPrag=NOUSERINLINE[final]] :: Int -> Int
                  case T7865.$wexpensive ww1 of ww2 [Occ=Once] { __DEFAULT ->
 expensive
       case T7865.$wexpensive ww1 of ww2 { __DEFAULT -> GHC.Types.I# ww2 }
diff --git a/testsuite/tests/simplCore/should_compile/all.T b/testsuite/tests/simplCore/should_compile/all.T
index 499e057b18..4c301cd6f2 100644
--- a/testsuite/tests/simplCore/should_compile/all.T
+++ b/testsuite/tests/simplCore/should_compile/all.T
@@ -324,3 +324,7 @@ test('T18120', normal, compile, ['-dcore-lint -O'])
 # WW worker m1). Ideally, it would be one, but we fail to inline dead-ending
 # recursive groups due to Note [Bottoming floats].
 test('T18231', [ only_ways(['optasm']), grep_errmsg(r'^[\w\.]+ ::.*->.*') ], compile, ['-ddump-simpl -dsuppress-idinfo -dppr-cols=99999 -dsuppress-uniques'])
+
+# Cast WW
+test('T17673', [ only_ways(['optasm']), grep_errmsg(r'^\w+\.\$wf') ], compile, ['-ddump-simpl -dsuppress-uniques -dppr-cols=9999'])
+test('T18078', [ only_ways(['optasm']), grep_errmsg(r'^\w+\.\$wf') ], compile, ['-ddump-simpl -dsuppress-uniques -dppr-cols=9999'])
diff --git a/testsuite/tests/stranal/should_compile/T16029.stdout b/testsuite/tests/stranal/should_compile/T16029.stdout
index 26c2973852..100b0791ca 100644
--- a/testsuite/tests/stranal/should_compile/T16029.stdout
+++ b/testsuite/tests/stranal/should_compile/T16029.stdout
@@ -1,4 +1,4 @@
-T16029.$WMkT [InlPrag=INLINE[0] CONLIKE] :: Int -> Int -> T
+T16029.$WMkT [InlPrag=INLINE[final] CONLIKE] :: Int -> Int -> T
          Tmpl= \ (dt [Occ=Once!] :: Int) (dt [Occ=Once!] :: Int) ->
   = \ (dt [Occ=Once!] :: Int) (dt [Occ=Once!] :: Int) ->
   :: GHC.Prim.Int# -> GHC.Prim.Int#