compare_five_hi.sh

#!/usr/bin/env bash

set -euo pipefail

if ! command -v icdiff >/dev/null 2>&1; then
  echo "error: icdiff is required to compare interface files" >&2
  exit 1
fi

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
GHC_BIN="${GHC_BIN:-${SCRIPT_DIR}/../_build/stage1/bin/ghc}"

if [[ ! -x "$GHC_BIN" ]]; then
  echo "error: set GHC_BIN to a built ghc (current: '$GHC_BIN')" >&2
  exit 1
fi

SRC="${SCRIPT_DIR}/ProcessTop.hs"
if [[ ! -f "$SRC" ]]; then
  echo "error: expected $SRC to exist" >&2
  exit 1
fi

WORKDIR="$(mktemp -d "${TMPDIR:-/tmp}/five-hi-XXXXXX")"
trap 'rm -rf "$WORKDIR"' EXIT
SRC_DIR="$(dirname "$SRC")"
UUID_COMMON="$SRC_DIR/UUIDCommon.hs"
MID_MODULES=(
  "$SRC_DIR/ProcessAlpha.hs"
  "$SRC_DIR/ProcessBeta.hs"
)

build_iface () {
  local label="$1"
  local order="$2"
  shift 2
  local dir="${WORKDIR}/${label}"
  mkdir -p "$dir"
  local modules=("$UUID_COMMON")
  if [[ "$order" == "normal" ]]; then
    modules+=("${MID_MODULES[@]}")
  else
    for ((idx=${#MID_MODULES[@]}-1; idx>=0; idx--)); do
      modules+=("${MID_MODULES[idx]}")
    done
  fi
  modules+=("$SRC")
  "$GHC_BIN" -j -ddump-ds-preopt -fwrite-if-simplified-core  -fforce-recomp --make "${modules[@]}" -outputdir "$dir" -hidir "$dir" -odir "$dir" "$@" >&2
  "$GHC_BIN" --show-iface "${dir}/ProcessTop.hi" > "${dir}/ProcessTop.iface"
  echo "${dir}/ProcessTop.iface"
}

for run in {1..1}; do
  echo "=== Run $run ==="
  iface_normal=$(build_iface "normal_$run" normal)
  iface_reverse=$(build_iface "reverse_$run" reverse -dinitial-unique=16777215 -dunique-increment=-1)

  icdiff "$iface_normal" "$iface_reverse" || true

  echo
  echo "=== KindRep bindings from normal interface (run $run) ==="
  rg -n "\$krep" -n "$iface_normal" || true

  cp "$iface_normal" "$SCRIPT_DIR/ProcessTop.normal.run${run}.iface"
  cp "$iface_reverse" "$SCRIPT_DIR/ProcessTop.reverse.run${run}.iface"
done

ProcessAlpha.hs

{-# LANGUAGE DataKinds #-}

module ProcessAlpha where

import UUIDCommon

type AlphaProcessId = UUID "AlphaProcess"

ProcessBeta.hs

{-# LANGUAGE DataKinds #-}

module ProcessBeta where

import UUIDCommon

type BetaAccountId = UUID "BetaAccount"

ProcessTop.hs

{-# LANGUAGE DataKinds #-}
{-# LANGUAGE KindSignatures #-}

module ProcessTop where

import ProcessAlpha (AlphaProcessId)
import ProcessBeta (BetaAccountId)
import UUIDCommon

-- Minimal reproducer for nondeterministic Typeable KindRep ordering:
-- these tycons share identical kinds (AlphaProcessId or BetaTransactionId).
-- Different unique supplies or module orders reshuffle the shared KindRep
-- bindings in the resulting interface file.

data AlphaProcessCarrier (ref :: AlphaProcessId) = AlphaProcessCarrier

data BetaTransactionMirror (ref :: BetaAccountId) = BetaTransactionMirror

UUIDCommon.hs

{-# LANGUAGE DataKinds #-}
{-# LANGUAGE GADTs #-}
{-# LANGUAGE KindSignatures #-}

module UUIDCommon
  ( UUID(..)
  ) where

import GHC.TypeLits (Symbol)

-- | Simple phantom UUID type indexed by a type-level label.
data UUID (label :: Symbol) = UUID