Small issue with signatures in a TH splice (fixes Trac #8932)

4 files changed, 29 insertions, 2 deletions

diff --git a/compiler/rename/RnEnv.lhs b/compiler/rename/RnEnv.lhs
index 49cbbad13d..178f722d99 100644
--- a/compiler/rename/RnEnv.lhs
+++ b/compiler/rename/RnEnv.lhs
@@ -270,8 +270,16 @@ lookupExactOcc name
                        ; return name
                        }
 
-           [gre] -> return (gre_name gre)
-           _     -> pprPanic "lookupExactOcc" (ppr name $$ ppr gres) }
+           (gre:_) -> return (gre_name gre) }
+           -- We can get more than one GRE here, if there are multiple 
+           -- bindings for the same name; but there will already be a 
+           -- reported error for the duplicate.  (If we add the error 
+           -- rather than stopping when we encounter it.) 
+           -- So all we need do here is not crash.  
+           -- Example is Trac #8932:
+           --    $( [d| foo :: a->a; foo x = x |])
+           --    foo = True
+           -- Here the 'foo' in the splice turns into an Exact Name
 
   where
     exact_nm_err = hang (ptext (sLit "The exact Name") <+> quotes (ppr name) <+> ptext (sLit "is not in scope"))
diff --git a/testsuite/tests/th/T8932.hs b/testsuite/tests/th/T8932.hs
new file mode 100644
index 0000000000..05630f331f
--- /dev/null
+++ b/testsuite/tests/th/T8932.hs
@@ -0,0 +1,12 @@
+{-# LANGUAGE TemplateHaskell #-}
+
+module T8932 where
+
+$([d|
+   foo :: a -> a
+   foo x = x
+  |])
+
+foo :: a
+foo = undefined
+
diff --git a/testsuite/tests/th/T8932.stderr b/testsuite/tests/th/T8932.stderr
new file mode 100644
index 0000000000..0e0f9774d5
--- /dev/null
+++ b/testsuite/tests/th/T8932.stderr
@@ -0,0 +1,5 @@
+

+T8932.hs:11:1:

+    Multiple declarations of ‘foo’

+    Declared at: T8932.hs:5:3

+                 T8932.hs:11:1

diff --git a/testsuite/tests/th/all.T b/testsuite/tests/th/all.T
index 19cc2e42b8..ce723dd304 100644
--- a/testsuite/tests/th/all.T
+++ b/testsuite/tests/th/all.T
@@ -324,3 +324,5 @@ test('T7021',
 test('T8807', normal, compile, ['-v0'])
 test('T8884', normal, compile, ['-v0'])
 test('T8954', normal, compile, ['-v0'])
+test('T8932', normal, compile_fail, ['-v0'])
+