[commit: ghc] master: Load orphan interfaces before checking if module implements signature (9c9a222)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/9c9a2229fe741c55a8fb8d0c6380ec066a77722b/ghc

>---------------------------------------------------------------

commit 9c9a2229fe741c55a8fb8d0c6380ec066a77722b
Author: Edward Z. Yang <ezyang at cs.stanford.edu>
Date:   Tue Dec 13 18:03:47 2016 -0800

    Load orphan interfaces before checking if module implements signature
    
    Summary:
    If we didn't load the orphans, we might conclude an instance
    is not implemented when it is.  See test bkp42.
    
    Signed-off-by: Edward Z. Yang <ezyang at cs.stanford.edu>
    
    Test Plan: validate
    
    Reviewers: simonpj, austin, bgamari
    
    Subscribers: thomie
    
    Differential Revision: https://phabricator.haskell.org/D2841


>---------------------------------------------------------------

9c9a2229fe741c55a8fb8d0c6380ec066a77722b
 compiler/typecheck/TcBackpack.hs                           |  5 +++++
 testsuite/tests/backpack/should_compile/all.T              |  1 +
 .../tests/backpack/should_compile/{bkp41.bkp => bkp42.bkp} |  9 ++++++---
 testsuite/tests/backpack/should_compile/bkp42.stderr       | 14 ++++++++++++++
 4 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/compiler/typecheck/TcBackpack.hs b/compiler/typecheck/TcBackpack.hs
index b6623cd..1cf3393 100644
--- a/compiler/typecheck/TcBackpack.hs
+++ b/compiler/typecheck/TcBackpack.hs
@@ -549,6 +549,11 @@ checkImplements impl_mod (IndefModule uid mod_name) = do
                     (gresFromAvails Nothing (mi_exports impl_iface))
         nsubst = mkNameShape (moduleName impl_mod) (mi_exports impl_iface)
 
+    -- Load all the orphans, so the subsequent 'checkHsigIface' sees
+    -- all the instances it needs to
+    loadModuleInterfaces (text "Loading orphan modules (from implementor of hsig)")
+                         (dep_orphs (mi_deps impl_iface))
+
     dflags <- getDynFlags
     let avails = calculateAvails dflags
                     impl_iface False{- safe -} False{- boot -}
diff --git a/testsuite/tests/backpack/should_compile/all.T b/testsuite/tests/backpack/should_compile/all.T
index 1f0136f..bb77278 100644
--- a/testsuite/tests/backpack/should_compile/all.T
+++ b/testsuite/tests/backpack/should_compile/all.T
@@ -33,3 +33,4 @@ test('bkp38', normal, backpack_compile, [''])
 test('bkp39', normal, backpack_compile, [''])
 test('bkp40', normal, backpack_compile, [''])
 test('bkp41', normal, backpack_compile, [''])
+test('bkp42', normal, backpack_compile, [''])
diff --git a/testsuite/tests/backpack/should_compile/bkp41.bkp b/testsuite/tests/backpack/should_compile/bkp42.bkp
similarity index 66%
copy from testsuite/tests/backpack/should_compile/bkp41.bkp
copy to testsuite/tests/backpack/should_compile/bkp42.bkp
index e8b5b24..59590f9 100644
--- a/testsuite/tests/backpack/should_compile/bkp41.bkp
+++ b/testsuite/tests/backpack/should_compile/bkp42.bkp
@@ -5,14 +5,17 @@ unit impl where
         import A
         instance Show T where
             show T = "T"
+    module C(module B) where
+        import B
 
 unit sig where
     signature B where
-        data T = T
+        data T
         instance Show T
     module App where
         import B
-        app = print T
+        app :: T -> IO ()
+        app t = print t
 
 unit main where
-    dependency sig[B=impl:B]
+    dependency sig[B=impl:C]
diff --git a/testsuite/tests/backpack/should_compile/bkp42.stderr b/testsuite/tests/backpack/should_compile/bkp42.stderr
new file mode 100644
index 0000000..69d8d7c
--- /dev/null
+++ b/testsuite/tests/backpack/should_compile/bkp42.stderr
@@ -0,0 +1,14 @@
+[1 of 3] Processing impl
+  Instantiating impl
+  [1 of 3] Compiling A                ( impl/A.hs, bkp42.out/impl/A.o )
+  [2 of 3] Compiling B                ( impl/B.hs, bkp42.out/impl/B.o )
+  [3 of 3] Compiling C                ( impl/C.hs, bkp42.out/impl/C.o )
+[2 of 3] Processing sig
+  [1 of 2] Compiling B[sig]           ( sig/B.hsig, nothing )
+  [2 of 2] Compiling App              ( sig/App.hs, nothing )
+[3 of 3] Processing main
+  Instantiating main
+  [1 of 1] Including sig[B=impl:C]
+    Instantiating sig[B=impl:C]
+    [1 of 2] Compiling B[sig]           ( sig/B.hsig, bkp42.out/sig/sig-Ko6MwJiRFc509cOdDShPV5/B.o )
+    [2 of 2] Compiling App              ( sig/App.hs, bkp42.out/sig/sig-Ko6MwJiRFc509cOdDShPV5/App.o )