Implement deriving strategies

Allows users to explicitly request which approach to `deriving` to use
via keywords, e.g.,

```
newtype Foo = Foo Bar
  deriving Eq
  deriving stock    Ord
  deriving newtype Show
```

Fixes #10598. Updates haddock submodule.

Test Plan: ./validate

Reviewers: hvr, kosmikus, goldfire, alanz, bgamari, simonpj, austin,
erikd, simonmar

Reviewed By: alanz, bgamari, simonpj

Subscribers: thomie, mpickering, oerjan

Differential Revision: https://phabricator.haskell.org/D2280

GHC Trac Issues: #10598

4 files changed, 59 insertions, 0 deletions

diff --git a/testsuite/tests/ghc-api/annotations/Makefile b/testsuite/tests/ghc-api/annotations/Makefile
index c557c66624..158dadb72c 100644
--- a/testsuite/tests/ghc-api/annotations/Makefile
+++ b/testsuite/tests/ghc-api/annotations/Makefile
@@ -112,6 +112,10 @@ T11018:
 T10276:
 	$(CHECK_API_ANNOTATIONS) "`'$(TEST_HC)' $(TEST_HC_OPTS) --print-libdir | tr -d '\r'`" Test10276.hs
 
+.PHONY: T10598
+T10598:
+	$(CHECK_API_ANNOTATIONS) "`'$(TEST_HC)' $(TEST_HC_OPTS) --print-libdir | tr -d '\r'`" Test10598.hs
+
 .PHONY: T11321
 T11321:
 	$(CHECK_API_ANNOTATIONS) "`'$(TEST_HC)' $(TEST_HC_OPTS) --print-libdir | tr -d '\r'`" Test11321.hs
diff --git a/testsuite/tests/ghc-api/annotations/T10598.stdout b/testsuite/tests/ghc-api/annotations/T10598.stdout
new file mode 100644
index 0000000000..21029da26d
--- /dev/null
+++ b/testsuite/tests/ghc-api/annotations/T10598.stdout
@@ -0,0 +1,36 @@
+---Problems (should be empty list)---
+[]
+---Annotations-----------------------
+-- SrcSpan the annotation is attached to, AnnKeywordId,
+--    list of locations the keyword item appears in
+[
+((Test10598.hs:1:1,AnnModule), [Test10598.hs:5:1-6]),
+((Test10598.hs:1:1,AnnWhere), [Test10598.hs:5:18-22]),
+((Test10598.hs:(7,1)-(9,10),AnnClass), [Test10598.hs:7:1-5]),
+((Test10598.hs:(7,1)-(9,10),AnnSemi), [Test10598.hs:11:1]),
+((Test10598.hs:(7,1)-(9,10),AnnWhere), [Test10598.hs:7:11-15]),
+((Test10598.hs:8:3-21,AnnDcolon), [Test10598.hs:8:5-6]),
+((Test10598.hs:8:3-21,AnnSemi), [Test10598.hs:9:3]),
+((Test10598.hs:8:8-21,AnnRarrow), [Test10598.hs:8:16-17]),
+((Test10598.hs:9:3-10,AnnEqual), [Test10598.hs:9:7]),
+((Test10598.hs:9:3-10,AnnFunId), [Test10598.hs:9:3]),
+((Test10598.hs:(11,1)-(12,10),AnnInstance), [Test10598.hs:11:1-8]),
+((Test10598.hs:(11,1)-(12,10),AnnSemi), [Test10598.hs:14:1]),
+((Test10598.hs:(11,1)-(12,10),AnnWhere), [Test10598.hs:11:16-20]),
+((Test10598.hs:12:3-10,AnnEqual), [Test10598.hs:12:7]),
+((Test10598.hs:12:3-10,AnnFunId), [Test10598.hs:12:3]),
+((Test10598.hs:(14,1)-(17,21),AnnEqual), [Test10598.hs:14:13]),
+((Test10598.hs:(14,1)-(17,21),AnnNewtype), [Test10598.hs:14:1-7]),
+((Test10598.hs:(14,1)-(17,21),AnnSemi), [Test10598.hs:18:1]),
+((Test10598.hs:15:3-22,AnnDeriving), [Test10598.hs:15:3-10]),
+((Test10598.hs:16:3-23,AnnDeriving), [Test10598.hs:16:3-10]),
+((Test10598.hs:16:12-16,AnnStock), [Test10598.hs:16:12-16]),
+((Test10598.hs:17:3-21,AnnDeriving), [Test10598.hs:17:3-10]),
+((Test10598.hs:17:12-19,AnnAnyclass), [Test10598.hs:17:12-19]),
+((Test10598.hs:18:1-34,AnnDeriving), [Test10598.hs:18:1-8]),
+((Test10598.hs:18:1-34,AnnInstance), [Test10598.hs:18:18-25]),
+((Test10598.hs:18:1-34,AnnSemi), [Test10598.hs:19:1]),
+((Test10598.hs:18:10-16,AnnNewtype), [Test10598.hs:18:10-16]),
+((<no location info>,AnnEofPos), [Test10598.hs:19:1])
+]
+
diff --git a/testsuite/tests/ghc-api/annotations/Test10598.hs b/testsuite/tests/ghc-api/annotations/Test10598.hs
new file mode 100644
index 0000000000..8a7651c154
--- /dev/null
+++ b/testsuite/tests/ghc-api/annotations/Test10598.hs
@@ -0,0 +1,18 @@
+{-# LANGUAGE DeriveAnyClass #-}
+{-# LANGUAGE DerivingStrategies #-}
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
+{-# LANGUAGE StandaloneDeriving #-}
+module Test10598 where
+
+class C a where
+  c :: proxy a -> Int
+  c _ = 42
+
+instance C Int where
+  c _ = 27
+
+newtype Foo = MkFoo Int
+  deriving          Eq
+  deriving stock    Ord
+  deriving anyclass C
+deriving newtype instance Show Foo
diff --git a/testsuite/tests/ghc-api/annotations/all.T b/testsuite/tests/ghc-api/annotations/all.T
index c14153dfbb..fac5d56658 100644
--- a/testsuite/tests/ghc-api/annotations/all.T
+++ b/testsuite/tests/ghc-api/annotations/all.T
@@ -21,6 +21,7 @@ test('T10313',      normal, run_command, ['$MAKE -s --no-print-directory T10313'
 test('T11018',      normal, run_command, ['$MAKE -s --no-print-directory T11018'])
 test('bundle-export', normal, run_command, ['$MAKE -s --no-print-directory bundle-export'])
 test('T10276',      normal, run_command, ['$MAKE -s --no-print-directory T10276'])
+test('T10598',      normal, run_command, ['$MAKE -s --no-print-directory T10598'])
 test('T11321',      normal, run_command, ['$MAKE -s --no-print-directory T11321'])
 test('T11332',      normal, run_command, ['$MAKE -s --no-print-directory T11332'])
 test('T11430',      normal, run_command, ['$MAKE -s --no-print-directory T11430'])