Fail before checking instances in checkHsigIface if exports don't match (#19244)

1 files changed, 21 insertions, 0 deletions

diff --git a/testsuite/tests/backpack/should_fail/T19244b.stderr b/testsuite/tests/backpack/should_fail/T19244b.stderr
new file mode 100644
index 0000000000..3a50d11079
--- /dev/null
+++ b/testsuite/tests/backpack/should_fail/T19244b.stderr
@@ -0,0 +1,21 @@
+[1 of 3] Processing user
+  [1 of 2] Compiling Map[sig]         ( user/Map.hsig, nothing )
+  [2 of 2] Compiling User             ( user/User.hs, nothing )
+[2 of 3] Processing ordmap
+  Instantiating ordmap
+  [1 of 1] Compiling Map              ( ordmap/Map.hs, T19244b.out/ordmap/Map.o )
+[3 of 3] Processing main
+  Instantiating main
+  [1 of 1] Including user[Map=ordmap:Map]
+    Instantiating user[Map=ordmap:Map]
+    [1 of 2] Compiling Map[sig]         ( user/Map.hsig, T19244b.out/user/user-GzloW2NeDdA2M0V8qzN4g2/Map.o )
+
+T19244b.bkp:11:27: error:
+    • Type constructor ‘Key’ has conflicting definitions in the module
+      and its hsig file
+      Main module: type Key :: * -> Constraint
+                   type Key = GHC.Classes.Ord :: * -> Constraint
+      Hsig file:  type Key :: forall {k}. k -> Constraint
+                  class Key k1
+      The types have different kinds
+    • while checking that ordmap:Map implements signature Map in user[Map=ordmap:Map]