From 1add44c40621fa3dd783b805e27038ff62e773c0 Mon Sep 17 00:00:00 2001
From: Jonathan Knowles <jonathan.knowles@iohk.io>
Date: Tue, 23 Nov 2021 05:43:14 +0000
Subject: [PATCH] Replace function `coinToInteger` with safer equivalent.

We use `intCast` instead of `fromIntegral`, which statically checks
that the conversion is safe.

We also use the same naming convention as the existing safe conversion
functions.
---
 lib/core/src/Cardano/Wallet.hs                       |  4 ++--
 lib/core/src/Cardano/Wallet/Primitive/Types/Coin.hs  | 12 +++++++-----
 .../unit/Cardano/Wallet/Shelley/TransactionSpec.hs   |  6 +++---
 3 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/lib/core/src/Cardano/Wallet.hs b/lib/core/src/Cardano/Wallet.hs
index dd3e7452c70..e706334fe5c 100644
--- a/lib/core/src/Cardano/Wallet.hs
+++ b/lib/core/src/Cardano/Wallet.hs
@@ -373,7 +373,7 @@ import Cardano.Wallet.Primitive.Types
 import Cardano.Wallet.Primitive.Types.Address
     ( Address (..), AddressState (..) )
 import Cardano.Wallet.Primitive.Types.Coin
-    ( Coin (..), addCoin, coinToInteger, sumCoins )
+    ( Coin (..), addCoin, sumCoins )
 import Cardano.Wallet.Primitive.Types.Hash
     ( Hash (..) )
 import Cardano.Wallet.Primitive.Types.Redeemer
@@ -1160,7 +1160,7 @@ readNextWithdrawal ctx (Coin withdrawal) = do
             calcMinimumCost tl pp (mkTxCtx $ Coin 0) emptySkeleton
 
     let costOfWithdrawal =
-            coinToInteger costWith - coinToInteger costWithout
+            Coin.toInteger costWith - Coin.toInteger costWithout
 
     if toInteger withdrawal < 2 * costOfWithdrawal
     then pure (Coin 0)
diff --git a/lib/core/src/Cardano/Wallet/Primitive/Types/Coin.hs b/lib/core/src/Cardano/Wallet/Primitive/Types/Coin.hs
index f06c9bac9b4..6e173b3b705 100644
--- a/lib/core/src/Cardano/Wallet/Primitive/Types/Coin.hs
+++ b/lib/core/src/Cardano/Wallet/Primitive/Types/Coin.hs
@@ -18,6 +18,7 @@ module Cardano.Wallet.Primitive.Types.Coin
       -- * Conversions (Safe)
     , fromIntegral
     , fromWord64
+    , toInteger
     , toQuantity
     , toWord64
 
@@ -27,7 +28,6 @@ module Cardano.Wallet.Primitive.Types.Coin
     , unsafeToWord64
 
       -- * Compatibility
-    , coinToInteger
     , coinToNatural
     , unsafeNaturalToCoin
 
@@ -49,7 +49,7 @@ module Cardano.Wallet.Primitive.Types.Coin
     ) where
 
 import Prelude hiding
-    ( fromIntegral )
+    ( fromIntegral, toInteger )
 
 import Cardano.Numeric.Util
     ( equipartitionNatural, partitionNatural )
@@ -144,6 +144,11 @@ fromIntegral i = Coin <$> intCastMaybe i
 fromWord64 :: Word64 -> Coin
 fromWord64 = Coin . intCast
 
+-- | Converts a 'Coin' to an 'Integer' value.
+--
+toInteger :: Coin -> Integer
+toInteger = intCast . unCoin
+
 -- | Converts a 'Coin' to a 'Quantity'.
 --
 -- Returns 'Nothing' if the given value does not fit within the bounds of
@@ -224,9 +229,6 @@ unsafeToWord64 c = fromMaybe onError (toWord64 c)
                                Compatibility
 -------------------------------------------------------------------------------}
 
-coinToInteger :: Coin -> Integer
-coinToInteger = Prelude.fromIntegral . unCoin
-
 coinToNatural :: Coin -> Natural
 coinToNatural = unCoin
 
diff --git a/lib/shelley/test/unit/Cardano/Wallet/Shelley/TransactionSpec.hs b/lib/shelley/test/unit/Cardano/Wallet/Shelley/TransactionSpec.hs
index 647caa4d7c9..11b57e89d39 100644
--- a/lib/shelley/test/unit/Cardano/Wallet/Shelley/TransactionSpec.hs
+++ b/lib/shelley/test/unit/Cardano/Wallet/Shelley/TransactionSpec.hs
@@ -84,7 +84,7 @@ import Cardano.Wallet.Primitive.Types
 import Cardano.Wallet.Primitive.Types.Address
     ( Address (..) )
 import Cardano.Wallet.Primitive.Types.Coin
-    ( Coin (..), coinToInteger )
+    ( Coin (..) )
 import Cardano.Wallet.Primitive.Types.Coin.Gen
     ( genCoinPositive, shrinkCoinPositive )
 import Cardano.Wallet.Primitive.Types.Hash
@@ -661,11 +661,11 @@ feeCalculationSpec = describe "fee calculations" $ do
     fp = LinearFee (Quantity 100_000) (Quantity 100)
 
     minFee :: TransactionCtx -> Integer
-    minFee ctx = coinToInteger $ calcMinimumCost testTxLayer pp ctx sel
+    minFee ctx = Coin.toInteger $ calcMinimumCost testTxLayer pp ctx sel
       where sel = emptySkeleton
 
     minFeeSkeleton :: TxSkeleton -> Integer
-    minFeeSkeleton = coinToInteger . estimateTxCost pp
+    minFeeSkeleton = Coin.toInteger . estimateTxCost pp
 
     estimateTxSize' :: TxSkeleton -> Integer
     estimateTxSize' = fromIntegral . unTxSize . estimateTxSize