Unique-ify the names of top-level auxiliary bindings in derived instances (Trac #7947)

The problem and its solution are explained in
   Note [Auxiliary binders]
in TcGenDeriv

4 files changed, 23 insertions, 0 deletions

diff --git a/testsuite/tests/deriving/should_compile/T7947.hs b/testsuite/tests/deriving/should_compile/T7947.hs
new file mode 100644
index 0000000000..d4df4353e5
--- /dev/null
+++ b/testsuite/tests/deriving/should_compile/T7947.hs
@@ -0,0 +1,16 @@
+{-# LANGUAGE DeriveDataTypeable #-}
+{-# LANGUAGE StandaloneDeriving #-}
+
+module T7947 where
+
+import Data.Data
+import Data.Typeable
+
+import T7947a
+import qualified T7947b as B
+
+deriving instance Typeable A
+deriving instance Typeable B.B
+
+deriving instance Data A
+deriving instance Data B.B
diff --git a/testsuite/tests/deriving/should_compile/T7947a.hs b/testsuite/tests/deriving/should_compile/T7947a.hs
new file mode 100644
index 0000000000..eb5c7472a0
--- /dev/null
+++ b/testsuite/tests/deriving/should_compile/T7947a.hs
@@ -0,0 +1,3 @@
+module T7947a where
+
+data A = C1 | C2 | C
diff --git a/testsuite/tests/deriving/should_compile/T7947b.hs b/testsuite/tests/deriving/should_compile/T7947b.hs
new file mode 100644
index 0000000000..f17f1cd674
--- /dev/null
+++ b/testsuite/tests/deriving/should_compile/T7947b.hs
@@ -0,0 +1,3 @@
+module T7947b where
+
+data B = D1 | D2 | C
diff --git a/testsuite/tests/deriving/should_compile/all.T b/testsuite/tests/deriving/should_compile/all.T
index 2234dd552e..8d9023646c 100644
--- a/testsuite/tests/deriving/should_compile/all.T
+++ b/testsuite/tests/deriving/should_compile/all.T
@@ -52,4 +52,5 @@ test('T7269', normal, compile, [''])
 test('T9069', normal, compile, [''])
 test('T9359', normal, compile, [''])
 test('T4896', normal, compile, [''])
+test('T7947', extra_clean(['T7947a.o', 'T7947a.hi', 'T7947b.o', 'T7947b.hi']), multimod_compile, ['T7947', '-v0'])