Generate static closure for datacon with unpacked sums

Summary

GHC doesn't generate static closures when some field is an unpacked sum.

Steps to reproduce

Consider the following example:

module Test where

data A = A | B | C

data D = D !Bool !A

foo = D True B

Compile it with ghc-9.10 -O2 Test2.hs -fforce-recomp -ddump-cmm -dno-typeable-binds and get:

...
[section ""data" . Test.foo_closure" {
     Test.foo_closure:
         const Test.D_con_info;
         const GHC.Types.True_closure+2;
         const Test.B_closure+2;
         const 3; // STATIC_LINK field
 }]
...

foo is a statically allocated closure.

Now change the code to UNPACK A:

module Test where

data A = A | B | C

data D = D !Bool {-# UNPACK #-} !A

foo = D True B

Now foo isn't a statically allocated closure but:

[Test.foo_entry() { //  [R1]
         { info_tbls: [(cBv,
                        label: Test.foo_info
                        rep: HeapRep static { Thunk }
                        srt: Nothing)]
           stack_info: arg_space: 8
         }
     {offset
       cBv: // global
           _r1::P64 = R1;
           if ((Sp + -16) < SpLim) (likely: False) goto cBw; else goto cBx;
       cBx: // global
           Hp = Hp + 24;
           if (Hp > HpLim) (likely: False) goto cBz; else goto cBy;
       cBz: // global
           HpAlloc = 24;
           goto cBw;
       cBw: // global
           R1 = _r1::P64;
           call (stg_gc_enter_1)(R1) args: 8, res: 0, upd: 8;
       cBy: // global
           (_cBr::I64) = call "ccall" arg hints:  [PtrHint,
                                                   PtrHint]  result hints:  [PtrHint] newCAF(BaseReg, _r1::P64);
           if (_cBr::I64 == 0) goto cBt; else goto cBs;
       cBt: // global
           call (I64![_r1::P64])() args: 8, res: 0, upd: 8;
       cBs: // global
           I64[Sp - 16] = stg_bh_upd_frame_info;
           I64[Sp - 8] = _cBr::I64;
           I64[Hp - 16] = Test.D_con_info;
           P64[Hp - 8] = GHC.Types.True_closure+2;
           I64[Hp] = 2;
           R1 = Hp - 15;
           Sp = Sp - 16;
           call (P64[Sp])(R1) args: 24, res: 0, upd: 24;
     }
 },
 section ""data" . Test.foo_closure" {
     Test.foo_closure:
         const Test.foo_info;
         const 0;
         const 0;
         const 0;
 }]

Expected behavior

I would expect a static closure like this:

[section ""data" . Test.foo_closure" {
     Test.foo_closure:
         const Test.D_con_info;
         const GHC.Types.True_closure+2;
         const 2; // Tag of B
         const 3; // STATIC_LINK field
 }]