From 35a7f1f2b893587191bde0fd7ff51fc7d611f890 Mon Sep 17 00:00:00 2001
From: Phil de Joux <philderbeast@gmail.com>
Date: Sat, 26 Jun 2021 11:51:39 -0400
Subject: [PATCH 1/2] Add a test showing Alt in km as Alt in m.

---
 uom-plugin/test-suite-units/Tests.hs |  2 ++
 uom-plugin/test-suite-units/Z.hs     | 26 ++++++++++++++++++++++++--
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/uom-plugin/test-suite-units/Tests.hs b/uom-plugin/test-suite-units/Tests.hs
index 53e451e4..b5a60e61 100644
--- a/uom-plugin/test-suite-units/Tests.hs
+++ b/uom-plugin/test-suite-units/Tests.hs
@@ -77,6 +77,7 @@ import Test.Tasty.HUnit
 import Defs ()
 import ErrorTests
 import Z (z)
+import qualified Z (tests)
 
 -- Some basic examples
 
@@ -327,6 +328,7 @@ tests = testGroup "uom-plugin"
     , testCase "2.4 l/h in m" $ convert [u| 2.4 l/ha |] @?= [u| 2.4e-7 m |]
     , testCase "1 m^4 in l m" $ convert [u| 1 m^4 |] @?= [u| 1000 l m |]
     ]
+  , Z.tests
   , testGroup "errors"
     [ testCase "s/m ~ m/s"            $ mismatch1 `throws` mismatch1_errors
     , testCase "m + s"                $ mismatch2 `throws` mismatch2_errors
diff --git a/uom-plugin/test-suite-units/Z.hs b/uom-plugin/test-suite-units/Z.hs
index 3e727e84..7d72f83f 100644
--- a/uom-plugin/test-suite-units/Z.hs
+++ b/uom-plugin/test-suite-units/Z.hs
@@ -1,12 +1,21 @@
+{-# LANGUAGE DeriveGeneric #-}
+{-# LANGUAGE DataKinds #-}
 {-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE QuasiQuotes #-}
 {-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE UndecidableInstances #-}
 
 {-# OPTIONS_GHC -fplugin Data.UnitsOfMeasure.Plugin #-}
 {-# OPTIONS_GHC -fno-warn-missing-signatures #-}
 
-module Z (z) where
+module Z (Alt(..), z, tests) where
 
-import Data.UnitsOfMeasure.Convert (convert)
+import Test.Tasty
+import Test.Tasty.HUnit
+
+import Data.UnitsOfMeasure (Quantity, u)
+import Data.UnitsOfMeasure.Convert (Convertible, convert)
+import Data.UnitsOfMeasure.Defs ()
 
 
 -- Inferring this type used to lead to unit equations with occur-check
@@ -18,3 +27,16 @@ import Data.UnitsOfMeasure.Convert (convert)
 --   -> Quantity a v
 {-# ANN z "HLint: ignore Eta reduce" #-}
 z q = convert q
+
+newtype Alt a = Alt a
+
+instance (Convertible u [u| m |], q ~ Quantity Double u) => Show (Alt q) where
+    show (Alt x) = show y
+        where
+            y :: Quantity Double [u| m |]
+            y = convert x
+
+tests :: TestTree
+tests = testGroup "show via convert"
+    [ testCase "1.01km" $ show (Alt [u| 1.01 km |]) @?= "[u| 1010.0 m |]"
+    ]
\ No newline at end of file

From 7d44c5c012bde2395d890ed7ed0d8e846cc7bf2e Mon Sep 17 00:00:00 2001
From: Phil de Joux <philderbeast@gmail.com>
Date: Sat, 26 Jun 2021 12:04:08 -0400
Subject: [PATCH 2/2] =?UTF-8?q?Add=20a=20failure=20Pack=20(Unpack=20(Base?=
 =?UTF-8?q?=20"m"))=20/=3D=C2=A0Base=20"m".?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 uom-plugin/test-suite-units/Z.hs | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/uom-plugin/test-suite-units/Z.hs b/uom-plugin/test-suite-units/Z.hs
index 7d72f83f..f09bcbd1 100644
--- a/uom-plugin/test-suite-units/Z.hs
+++ b/uom-plugin/test-suite-units/Z.hs
@@ -8,7 +8,7 @@
 {-# OPTIONS_GHC -fplugin Data.UnitsOfMeasure.Plugin #-}
 {-# OPTIONS_GHC -fno-warn-missing-signatures #-}
 
-module Z (Alt(..), z, tests) where
+module Z (z, tests) where
 
 import Test.Tasty
 import Test.Tasty.HUnit
@@ -28,15 +28,23 @@ import Data.UnitsOfMeasure.Defs ()
 {-# ANN z "HLint: ignore Eta reduce" #-}
 z q = convert q
 
-newtype Alt a = Alt a
+newtype A a = A a
+newtype B a = B a
 
-instance (Convertible u [u| m |], q ~ Quantity Double u) => Show (Alt q) where
-    show (Alt x) = show y
+instance (Convertible u [u| m |], q ~ Quantity Double u) => Show (A q) where
+    show (A x) = show y
+        where
+            y :: Quantity Double [u| m |]
+            y = convert x
+
+instance (q ~ Quantity Double [u| m |]) => Show (B q) where
+    show (B x) = show y
         where
             y :: Quantity Double [u| m |]
             y = convert x
 
 tests :: TestTree
 tests = testGroup "show via convert"
-    [ testCase "1.01km" $ show (Alt [u| 1.01 km |]) @?= "[u| 1010.0 m |]"
+    [ testCase "A 1.01km" $ show (A [u| 1.01 km |]) @?= "[u| 1010.0 m |]"
+    , testCase "B 1010m" $ show (B [u| 1010.0 m |]) @?= "[u| 1010.0 m |]"
     ]
\ No newline at end of file