Synthesis attributes not found when using type aliases

[martijnbastiaan]

This:

module Test where

import Clash.Explicit.Prelude
import Clash.Annotations.SynthesisAttributes

top :: BitVector 1 `Annotate` [ 'StringAttr "chip_pin" "XX" ] -> BitVector 1 
top a = a

produces:

(* chip_pin = "XX" *) input [0:0] a

When using an intermediate type synonym, this fails. E.g., this:

module Test where

import Clash.Explicit.Prelude
import Clash.Annotations.SynthesisAttributes

type X = '[ 'StringAttr "chip_pin" "XX" ]

top :: BitVector 1 `Annotate` X -> BitVector 1 
top a = a

produces:

input [0:0] a

while I would expect them to behave identically. Weirdly, when using:

module Test where

import Clash.Explicit.Prelude
import Clash.Annotations.SynthesisAttributes

-- No []
type X = 'StringAttr "chip_pin" "XX"

top :: BitVector 1 `Annotate` X -> BitVector 1 
top a = a

Clash fails explicitly:

<no location info>: error:
    Clash error call:
    Expected StringAttr, IntegerAttr, BoolAttr or Attr constructor, got:Test.X
    CallStack (from HasCallStack):
      error, called at src-ghc/Clash/GHC/GHC2Core.hs:824:9 in clash-ghc-1.4.1-Fkb2bPkpKD58uHIycIlSqz:Clash.GHC.GHC2Core

---

This is an issue in GHC2Core. coreToAttrs & friends should account for type synonyms.